Imperial Roman army - AbsoluteAstronomy.com

The Imperial Roman army refers to the armed forces deployed by the Roman Empire

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

during the Principate

Principate

The Principate is the first period of the Roman Empire, extending from the beginning of the reign of Caesar Augustus to the Crisis of the Third Century, after which it was replaced with the Dominate. The Principate is characterized by a concerted effort on the part of the Emperors to preserve the...

era (30 BC – AD 284).

Under the founder–emperor Augustus

Augustus

Augustus ;23 September 63 BC – 19 August AD 14) is considered the first emperor of the Roman Empire, which he ruled alone from 27 BC until his death in 14 AD.The dates of his rule are contemporary dates; Augustus lived under two calendars, the Roman Republican until 45 BC, and the Julian...

(ruled 30 BC – AD 14 ), the legions

Roman legion

A Roman legion normally indicates the basic ancient Roman army unit recruited specifically from Roman citizens. The organization of legions varied greatly over time but they were typically composed of perhaps 5,000 soldiers, divided into maniples and later into "cohorts"...

, which were formations numbering about 5,000 heavy infantry

Heavy infantry

Heavy infantry refers to heavily armed and armoured ground troops, as opposed to medium or light infantry, in which the warriors are relatively lightly armoured. As modern infantry troops usually define their subgroups differently , 'heavy infantry' almost always is used to describe pre-gunpowder...

recruited from Roman citizens only, were transformed from a mixed conscript and volunteer corps serving an average of 10 years, to all-volunteer units of long-term professionals serving a standard 25-year term. (Conscription was only decreed in emergencies.) In the later 1st century, the size of a legion's First Cohort was doubled, increasing the strength of a legion to about 5,500.

To complement the legions, Augustus established the auxilia, a regular corps of similar numbers to the legions, recruited from the peregrini
Peregrinus (Roman)
Peregrinus was the term used during the early Roman empire, from 30 BC to 212 AD, to denote a free provincial subject of the Empire who was not a Roman citizen. Peregrini constituted the vast majority of the Empire's inhabitants in the 1st and 2nd centuries AD...

or non-citizen inhabitants of the empire, who constituted about 90% of the Empire's population in the 1st century. In addition to large numbers of heavy infantry equipped in a similar manner to legionaries, the auxilia provided virtually all the army's cavalry, light infantry, archers and other specialists. The auxilia were organised in units about 500 strong. These units were termed cohortes if they consisted of infantry, alae if they consisted of cavalry and cohortes equitatae if they were composed of infantry with a cavalry contingent attached.

Until about AD 68, the auxilia were recruited by a mix of conscription and voluntary enlistment. After that time, the auxilia became largely a volunteer corps, with conscription resorted to only in emergencies. Auxiliaries were required to serve a minimum of 25 years, although many served for longer periods. On completion of their minimum term, auxiliaries were awarded Roman citizenship, which carried important legal, fiscal and social advantages. Around AD 80, a minority of auxiliary regiments were doubled in size.

Alongside the regular forces, the army of the Principate employed allied native units (called numeri) from outside the Empire on a mercenary basis. These were led by their own aristocrats and equipped in traditional fashion. Numbers fluctuated according to circumstances and are largely unknown.

As all-citizen formations, and symbolic protectors of the dominance of the Italian "master-nation", legions enjoyed greater social prestige than the auxilia for much of the Principate. This was reflected in better pay and benefits. In addition, legionaries were equipped with more expensive and protective armour than auxiliaries, notably the lorica segmentata
Lorica segmentata
The lōrīca segmentāta was a type of segmented armour almost exclusively used in the Roman Empire, but the Latin name was first used in the 16th century...

, or laminated-strip armour. However, in 212, the Emperor Caracalla

Caracalla

Caracalla , was Roman emperor from 198 to 217. The eldest son of Septimius Severus, he ruled jointly with his younger brother Geta until he murdered the latter in 211...

granted Roman citizenship to all the Empire's inhabitants. At this point, the distinction between legions and auxilia became moot, the latter becoming all-citizen units also. The change was reflected in the disappearance, during the 3rd century, of legionaries' special equipment, and the progressive break-up of legions into cohort-sized units like the auxilia.

By the end of Augustus' reign, the imperial army numbered some 250,000 men, equally split between 25 legions and 250 units of auxiliaries. The numbers grew to a peak of about 450,000 by 211, in 33 legions and about 400 auxiliary units. By then, auxiliaries outnumbered legionaries substantially. From this peak, numbers probably underwent a steep decline by 270 due to plague and losses during multiple major barbarian invasions. Numbers were restored to their early 2nd-century level of ca. 400,000 (but probably not to their 211 peak) under Diocletian

Diocletian

Diocletian |latinized]] upon his accession to Diocletian . c. 22 December 244 – 3 December 311), was a Roman Emperor from 284 to 305....

(r. 284-305). After the Empire's borders became settled (on the Rhine-Danube

Danube

The Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....

line in Europe) by AD 68, virtually all military units (except the Praetorian Guard

Praetorian Guard

The Praetorian Guard was a force of bodyguards used by Roman Emperors. The title was already used during the Roman Republic for the guards of Roman generals, at least since the rise to prominence of the Scipio family around 275 BC...

) were stationed on or near the borders, in roughly 17 of the 42 provinces

Roman province

In Ancient Rome, a province was the basic, and, until the Tetrarchy , largest territorial and administrative unit of the empire's territorial possessions outside of Italy...

of the empire in the reign of Hadrian

Hadrian

Hadrian , was Roman Emperor from 117 to 138. He is best known for building Hadrian's Wall, which marked the northern limit of Roman Britain. In Rome, he re-built the Pantheon and constructed the Temple of Venus and Roma. In addition to being emperor, Hadrian was a humanist and was philhellene in...

(r. 117–138).

The military chain of command was relatively flat. In each province, the deployed legions' legati (legion commanders, who also controlled the auxiliary units attached to their legion) reported to the legatus Augusti pro praetore
Legatus Augusti pro praetore
A legatus Augusti pro praetore was the official title of the governor of some imperial provinces of the Roman Empire during the Principate era, normally the larger ones or those where legions were based...

(provincial governor), who also headed the civil administration. The governor in turn reported directly to the Emperor in Rome. There was no army general staff

German General Staff

The German General Staff was an institution whose rise and development gave the German armed forces a decided advantage over its adversaries. The Staff amounted to its best "weapon" for nearly a century and a half....

in Rome, but the leading praefectus praetorio (commander of the Praetorian Guard) often acted as the Emperor's de facto military chief-of-staff.

Compared to the subsistence-level peasant families from which they mostly originated, legionary rankers enjoyed considerable disposable income, enhanced by periodical cash bonuses on special occasions such as the accession of a new emperor. In addition, on completion of their term of service, they were given a generous discharge bonus equivalent to 13 years' salary. Auxiliaries were paid much less in the early 1st century, but by 100 AD, the differential had virtually disappeared. Similarly, in the earlier period, auxiliaries appear not to have received cash and discharge bonuses, but probably did so from the reign of Hadrian onwards. Junior officers (principales), the equivalent of non-commissioned officers in modern armies, could expect to earn up to twice basic pay. Legionary centurions, the equivalent of senior warrant officers, were organised in an elaborate hierarchy. Usually promoted from the ranks, they commanded the legion's tactical sub-units of centuriae (about 80 men) and cohort

Cohort (military unit)

A cohort was the basic tactical unit of a Roman legion following the reforms of Gaius Marius in 107 BC.-Legionary cohort:...

s (about 480 men). They were paid several multiples of basic pay. The most senior centurion, the primus pilus, was automatically elevated to equestrian rank on completion of his single-year term of office. The senior officers of the army, the legati legionis (legion commanders), tribuni militum (legion staff officers) and the praefecti (commanders of auxiliary regiments) were all of at least equestrian rank. In the 1st and early 2nd centuries, they were mainly Italian aristocrats performing the military component of their cursus honorum
Cursus honorum
The cursus honorum was the sequential order of public offices held by aspiring politicians in both the Roman Republic and the early Empire. It was designed for men of senatorial rank. The cursus honorum comprised a mixture of military and political administration posts. Each office had a minimum...

(conventional career-path). Later, provincial career officers became predominant. Senior officers were paid enormous salaries, multiples of at least 50 times a soldier's basic pay.

Soldiers spent only a fraction of their lives on campaign. Most of their time was spent on routine military duties such as training, patrolling, and maintenance of equipment etc. Soldiers also played an important role outside the military sphere. They performed the function of a provincial governor's police force. As a large, disciplined and skilled force of fit men, they played a crucial role in the construction of a province's military and civil infrastructure. In addition to constructing forts and fortified defences such as Hadrian's Wall

Hadrian's Wall

Hadrian's Wall was a defensive fortification in Roman Britain. Begun in AD 122, during the rule of emperor Hadrian, it was the first of two fortifications built across Great Britain, the second being the Antonine Wall, lesser known of the two because its physical remains are less evident today.The...

, they built roads, bridges, ports, public buildings and entire new cities (colonia

Colonia (Roman)

A Roman colonia was originally a Roman outpost established in conquered territory to secure it. Eventually, however, the term came to denote the highest status of Roman city.-History:...

), and cleared forests and drained marshes to expand a province's available arable land.

Soldiers, mostly drawn from polytheistic societies, enjoyed wide freedom of worship in the polytheistic Roman system. They revered equally their own native deities, Roman deities and the local deities of the provinces in which they served. Only a few cults were banned by the Roman authorities, as being incompatible with the official Roman religion or being politically subversive, notably Druidism and Christianity

Christianity

Christianity is a monotheistic religion based on the life and teachings of Jesus as presented in canonical gospels and other New Testament writings...

. The later Principate saw the rise in popularity among the military of Eastern mystery cults, generally centred on one deity, and involving secret rituals divulged only to initiates. By far the most popular cult in the army was Mithraism

Mithraism

The Mithraic Mysteries were a mystery religion practised in the Roman Empire from about the 1st to 4th centuries AD. The name of the Persian god Mithra, adapted into Greek as Mithras, was linked to a new and distinctive imagery...

, an apparently syncretist

Syncretism

Syncretism is the combining of different beliefs, often while melding practices of various schools of thought. The term means "combining", but see below for the origin of the word...

cult which mainly originated in Asia Minor

Asia Minor

Asia Minor is a geographical location at the westernmost protrusion of Asia, also called Anatolia, and corresponds to the western two thirds of the Asian part of Turkey...

Sources

Except for the early 1st century, the literary evidence for the Principate period is surprisingly thin, due to the loss of a large number of contemporary historical works. From the point of view of the imperial army, the most useful works are those by the Roman historian Tacitus

Tacitus

Publius Cornelius Tacitus was a senator and a historian of the Roman Empire. The surviving portions of his two major works—the Annals and the Histories—examine the reigns of the Roman Emperors Tiberius, Claudius, Nero and those who reigned in the Year of the Four Emperors...

, writing around AD 100. These are the Annales
Annals (Tacitus)
The Annals by Tacitus is a history of the reigns of the four Roman Emperors succeeding Caesar Augustus. The surviving parts of the Annals extensively cover most of the reigns of Tiberius and Nero. The title Annals was probably not given by Tacitus, but derives from the fact that he treated this...

, a chronicle of the Julio-Claudian era from the death of the founder-emperor Augustus

Augustus

to that of Nero

Nero

Nero , was Roman Emperor from 54 to 68, and the last in the Julio-Claudian dynasty. Nero was adopted by his great-uncle Claudius to become his heir and successor, and succeeded to the throne in 54 following Claudius' death....

(AD 14-68). Even this suffers from large gaps, amounting to about a third of the original; the Historiae
Histories (Tacitus)
Histories is a book by Tacitus, written c. 100–110, which covers the Year of Four Emperors following the downfall of Nero, the rise of Vespasian, and the rule of the Flavian Dynasty up to the death of Domitian.thumb|180px|Tacitus...

was the sequel to the Annales, bringing the chronicle up to the death of Domitian

Domitian

Domitian was Roman Emperor from 81 to 96. Domitian was the third and last emperor of the Flavian dynasty.Domitian's youth and early career were largely spent in the shadow of his brother Titus, who gained military renown during the First Jewish-Roman War...

(AD 96), of which only the first part, a detailed account of the Civil War of 68-9

Year of the Four Emperors

The Year of the Four Emperors was a year in the history of the Roman Empire, AD 69, in which four emperors ruled in a remarkable succession. These four emperors were Galba, Otho, Vitellius, and Vespasian....

survives; and the Agricola
Agricola (book)
The Agricola is a book by the Roman historian Tacitus, written c 98, which recounts the life of his father-in-law Gnaeus Julius Agricola, an eminent Roman general. It also covers, briefly, the geography and ethnography of ancient Britain...

, a biography of Tacitus' own father-in-law, Gnaeus Julius Agricola

Gnaeus Julius Agricola

Gnaeus Julius Agricola was a Roman general responsible for much of the Roman conquest of Britain. His biography, the De vita et moribus Iulii Agricolae, was the first published work of his son-in-law, the historian Tacitus, and is the source for most of what is known about him.Born to a noted...

, who as governor of Britain (AD 78-85) attempted to subjugate Caledonia

Caledonia

Caledonia is the Latinised form and name given by the Romans to the land in today's Scotland north of their province of Britannia, beyond the frontier of their empire...

(Scotland) to Roman rule. The second important literary source is De Re Militari
De Re Militari
De Re Militari , also Epitoma Rei Militaris, is a treatise by the late Latin writer Vegetius about Roman warfare and military principles as a presentation of methods and practices in use during the height of Rome's power, and responsible for that power...

, a treatise on Roman military practices by Vegetius

Vegetius

Publius Flavius Vegetius Renatus, commonly referred to simply as Vegetius, was a writer of the Later Roman Empire. Nothing is known of his life or station beyond what he tells us in his two surviving works: Epitoma rei militaris , and the lesser-known Digesta Artis Mulomedicinae, a guide to...

, written ca. 400. This contains much useful material relating to the Principate period, but the author's statements are undated and sometimes unreliable. Also useful are; The Jewish War by Josephus

Josephus

Titus Flavius Josephus , also called Joseph ben Matityahu , was a 1st-century Romano-Jewish historian and hagiographer of priestly and royal ancestry who recorded Jewish history, with special emphasis on the 1st century AD and the First Jewish–Roman War, which resulted in the Destruction of...

, an eyewitness account of the First Jewish revolt of AD 66-70 by one of the Jewish commanders who defected to the Romans after he was captured; the essay Acies contra Alanos (Ektaxis kata Alanon) by the Greek author Arrian

Arrian

Lucius Flavius Arrianus 'Xenophon , known in English as Arrian , and Arrian of Nicomedia, was a Roman historian, public servant, a military commander and a philosopher of the 2nd-century Roman period...

, who was imperial governor of Cappadocia

Cappadocia (Roman province)

Cappadocia was a province of the Roman empire in Anatolia , with its capital at Caesarea. It was established in 17 AD by the emperor Tiberius , following the death of Cappadocia's last king, Archelaus. It was an imperial province, meaning that its governor was directly appointed by the emperor...

in AD 135-8: this describes a campaign led by the author to repel an invasion of his province by the Alans

Alans

The Alans, or the Alani, occasionally termed Alauni or Halani, were a group of Sarmatian tribes, nomadic pastoralists of the 1st millennium AD who spoke an Eastern Iranian language which derived from Scytho-Sarmatian and which in turn evolved into modern Ossetian.-Name:The various forms of Alan —...

, an Iranic people of the Caucasus

Caucasus

The Caucasus, also Caucas or Caucasia , is a geopolitical region at the border of Europe and Asia, and situated between the Black and the Caspian sea...

region. But most Roman historians present only a very limited picture of the imperial army's affairs, as they describe only military campaigns and say little about the army's organisation, logistics and the daily lives of the troops. Fortunately, the thin and fragmentary literary evidence has been complemented by a vast mass of inscription and archaeological evidence.

The imperial army was a highly bureaucratised institution. Meticulous financial records were kept by units' cornicularii (book-keepers). Detailed records were kept on all individual soldiers and there is evidence of filing systems. Even minor matters such as soldiers' requests to their praefectus for leave (commeatus) had to be submitted in writing. From the evidence discovered at Vindolanda

Vindolanda

Vindolanda was a Roman auxiliary fort just south of Hadrian's Wall in northern England. Located near the modern village of Bardon Mill, it guarded the Stanegate, the Roman road from the River Tyne to the Solway Firth...

, a fort near Hadrian's Wall

Hadrian's Wall

, it can be deduced that the Roman garrison in the province of Britain alone generated tens of millions of documents. However, only an infinitesimal fraction of this vast documentation has survived, due to organic decomposition of the writing-medium (wooden and wax-tablets and papyrus

Papyrus

Papyrus is a thick paper-like material produced from the pith of the papyrus plant, Cyperus papyrus, a wetland sedge that was once abundant in the Nile Delta of Egypt....

). The only region of the empire where the army's documentation has survived in significant quantities is Egypt

Egypt

Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...

, where exceptionally dry conditions have prevented decomposition. Egyptian papyri are thus a crucial source for the army's internal organisation and life. The Vindolanda tablets

Vindolanda tablets

The Vindolanda tablets are "the oldest surviving handwritten documents in Britain". They are also probably our best source of information about life on Hadrian's Wall. Written on fragments of thin, post-card sized wooden leaf-tablets with carbon-based ink, the tablets date to the 1st and 2nd...

, documents inscribed on wooden tablets and preserved by unusual anoxic conditions, are a rare corpus of army documents from the north-western part of the Empire. They consist of a series of letters and memoranda between officers of three auxiliary regiments stationed in succession at Vindolanda AD 85–122. They provide a valuable glimpse of the real lives and activities of the garrison of an auxiliary fort.

A large corpus of inscription evidence has been preserved on inorganic materials such as metal or stone. Of outstanding importance among stone monuments are the bas-reliefs on Trajan's Column

Trajan's Column

Trajan's Column is a Roman triumphal column in Rome, Italy, which commemorates Roman emperor Trajan's victory in the Dacian Wars. It was probably constructed under the supervision of the architect Apollodorus of Damascus at the order of the Roman Senate. It is located in Trajan's Forum, built near...

in Rome. Erected in 112 to celebrate the Emperor Trajan

Trajan

Trajan , was Roman Emperor from 98 to 117 AD. Born into a non-patrician family in the province of Hispania Baetica, in Spain Trajan rose to prominence during the reign of emperor Domitian. Serving as a legatus legionis in Hispania Tarraconensis, in Spain, in 89 Trajan supported the emperor against...

's successful conquest of Dacia (101-7), the reliefs provide the most comprehensive and detailed portrayal of Roman military equipment extant. Another major source on stone is the extensive corpus of recovered tombstones of Roman soldiers

Roman military tombstones

The archaeology of death in the Roman period provides great detail into the lives and practices of the Imperial Roman army.- Tombstone form :The most familiar form of commemoration in death is the standing stone stelae; stone slabs taller than they are wide upon which they are inscribed with simple...

. These often carry reliefs showing the subject in full combat dress plus inscriptions containing a summary of his career (age, units served, ranks held).

Notable metal documents are Roman military diplomas. A diploma was a bronze tablet issued to an auxiliary soldier on completion of his 25-year term of service to prove the award of Roman citizenship

Roman citizenship

Citizenship in ancient Rome was a privileged political and legal status afforded to certain free-born individuals with respect to laws, property, and governance....

to the holder and his family. A particular advantage of diplomas for historians is that they are dated. Diplomas also normally list the names of several auxiliary units which served in the same province at the same time, critical data on the deployment of auxiliary units in the various provinces of the Empire at different times. Also usually recorded are: beneficiary's regiment, regimental commander's name, beneficiary's military rank, name of beneficiary, name of beneficiary's father and origin (nation, tribe or city); name of beneficiary's wife and name of her father and origin; and names of children granted citizenship. Over 800 diplomas have been recovered, although most in a fragmentary state. Stone inscriptions relating to the army are mostly on soldiers' tombstones and dedications of altars. Such inscriptions yield important information on the origins and career-paths and religious beliefs of soldiers of all ranks, although officers predominate due to the expense of the memorials.

Finally, a mass of information has been uncovered by archaeological excavation of imperial military sites: legionary fortresses, auxiliary forts, marching-camps and other facilities such as signal-stations. A good example is Vindolanda fort itself, where excavations began in the 1930s and continue in 2010. Such excavations have uncovered details of the lay-out and facilities of military sites and remains of military equipment.

Background: the Caesarian Roman army

The army of the late Republic that Augustus took over on becoming sole ruler of the Empire in 30 BC consisted of a number of large (5,000-strong) formations called legions, which were composed exclusively of heavy infantry. The legion's light infantry (velites
Velites
Velites were a class of infantry in the Polybian legions of the early Roman republic. Velites were light infantry and skirmishers who were armed with a number of light javelins, or hastae velitares, to fling at the enemy, and also carried short thrusting swords, or gladii for use in melee...

) which had been deployed in earlier times (see Roman army of the mid-Republic

Roman army of the mid-Republic

The Roman army of the mid-Republic , refers to the armed forces deployed by the mid- Roman Republic The Roman army of the mid-Republic (also known as the manipular Roman army or the "Polybian army"), refers to the armed forces deployed by the mid- Roman Republic The Roman army of the mid-Republic...

), had been phased out as had its contingent of cavalry. Legions were recruited from Roman citizens only (i.e.: from Italians and inhabitants of Roman colonies outside Italy), by regular conscription, although by 88 BC, a substantial proportion of recruits were volunteers.

To remedy the deficiencies in capability of the legions (heavy and light cavalry, light infantry, archers and other specialists), the Romans relied on a motley array of irregular units of allied troops, both composed of subject natives of the empire's provinces (called the peregrini
Peregrinus (Roman)
Peregrinus was the term used during the early Roman empire, from 30 BC to 212 AD, to denote a free provincial subject of the Empire who was not a Roman citizen. Peregrini constituted the vast majority of the Empire's inhabitants in the 1st and 2nd centuries AD...

by the Romans) and of bands supplied, often on a mercenary basis, by Rome's allied kings beyond the Empire's borders. Led by their own aristocrats and equipped in their own traditional fashion, these native units varied widely in size, quality and reliability. Most would only be available for particular campaigns before returning home or disbanding.

Foundation of the imperial army under Augustus (30 BC - AD 14)

On gaining undisputed mastery over the Roman empire in 30 BC, Augustus

Augustus

(sole rule 30 BC - AD 14) was left with an army which was bloated by extraordinary recruitment for the Roman civil wars

Roman civil wars

There were several Roman civil wars, especially during the late Republic. The most famous of these are the war in the 40s BC between Julius Caesar and the optimate faction of the senatorial elite initially led by Pompey and the subsequent war between Caesar's successors, Octavian and Mark Antony in...

and at the same lacking a suitable organisation for the defence and expansion of a vast empire. Even after disbanding most of his defeated adversary Mark Anthony

Mark Antony

Marcus Antonius , known in English as Mark Antony, was a Roman politician and general. As a military commander and administrator, he was an important supporter and loyal friend of his mother's cousin Julius Caesar...

's legions, Augustus had 50 legions under his command, composed exclusively of Roman citizens i.e. by that time, of Italians and inhabitants of Roman colonies outside Italy. Alongside these were a mass of irregular non-Italian allied units whose command, size and equipment varied greatly. Some allied units came from provinces within the empire, others from beyond the imperial borders.

Legions

The first priority was to reduce the number of legions

Roman legion

to a sustainable level. 50 legions implied too high a recruitment burden for a male citizen-body only about 2 million strong, especially as Augustus intended to create a long-term career force. The Emperor retained just over half his legions (28), disbanding the rest and settling their veterans in no less than 28 new Roman colonies. The number of legions remained close to that level throughout the Principate (varying between 25 and 33 in number).

Unlike the Republican legions, which were, in theory at least, temporary citizen-levies for the duration of particular wars, Augustus and his right-hand man Agrippa clearly envisioned their legions as permanent units composed of career professionals. Under the late Republic, a Roman citizen iunior (i.e. male of military age: 16–46 years) could legally be required to serve a maximum of 16 years in the legions and a maximum of 6 years consecutively. The average number of years served was about 10. In 13 BC, Augustus decreed 16 years as the standard term of service for legionary recruits, with a further 4 years as reservists (evocati). In AD 5, the standard term was increased to 20 years plus 5 years in the reserves. In the period following its introduction, the new term was deeply unpopular with the troops. On Augustus' death in AD 14, the legions stationed on the river Rhine staged a major mutiny, and among other things, demanded a reversion to a 16-year term. Augustus prohibited serving legionaries from marrying, a decree that remained in force for 2 centuries. This measure was probably prudent in the early imperial period, when most legionaries were from Italy or the Roman colonies on the Mediterranean, and were required to serve long years far from home. This could lead to disaffection if they left families behind. But from about AD 100 onwards, when most legions were based long-term in the same frontier-province and recruitment was primarily local, the prohibition of marriage became a legal encumbrance that was largely ignored. Many legionaries formed stable relationships and brought up families. Their sons, although illegitimate in Roman law and thus unable to inherit their fathers' citizenship, were nevertheless frequently admitted to legions.

At the same time, the traditional grant of land to retiring veterans was made replaceable by a cash discharge bonus, as there was no longer sufficient state-owned land (ager publicus) in Italy to distribute. Unlike the Republic, which had relied primarily on conscription (i.e. compulsory levy), Augustus and Agrippa preferred volunteers for their professional legions. Given the onerous new term of service, it was necessary to offer a substantial bonus to attract sufficient citizen-recruits. In AD 5, the discharge bonus was set at 3,000 denarii. This was a generous sum equivalent to about 13 years' gross salary for a legionary of the time. To finance this major outlay, Augustus decreed a 5% tax on inheritances and 1% on auction-sales, to be paid into a dedicated aerarium militare (military treasury). However, veterans continued to be offered land instead of cash in Roman colonies established in the newly annexed frontier provinces, where public land was plentiful (as a result of confiscations from defeated indigenous tribes). This was another grievance behind the mutinies of 14 AD, as it effectively forced Italian veterans to settle far from their own country (or lose their bonus). The imperial authorities could not compromise on this issue, as the planting of colonies of Roman veterans was a crucial mechanism for controlling and Romanising a new province, and the foundation of veterans' colonies did not cease until the end of Trajan's rule (117). But as legionary recruitment became more localised (by AD 60, over half of recruits were not Italian-born), the issue became less relevant.

Augustus modified the command structure of the legion to reflect its new permanent, professional nature. In Republican tradition (but ever less in practice), each legion was under 6 equestrian military tribunes who took turns to command it pairs. But in the late Republic, military tribunes were eclipsed by higher-ranking officers of senatorial rank called legati ("literally "envoys"). A proconsul

Proconsul

A proconsul was a governor of a province in the Roman Republic appointed for one year by the senate. In modern usage, the title has been used for a person from one country ruling another country or bluntly interfering in another country's internal affairs.-Ancient Rome:In the Roman Republic, a...

(Republican governor) might ask the senate to appoint a number of legati to serve under him e.g. Julius Caesar, Augustus' grand-uncle and adoptive father, had 5, and later 10, legati attached to his staff when he was governor of Cisalpine Gaul

Cisalpine Gaul

Cisalpine Gaul, in Latin: Gallia Cisalpina or Citerior, also called Gallia Togata, was a Roman province until 41 BC when it was merged into Roman Italy.It bore the name Gallia, because the great body of its inhabitants, after the expulsion of the Etruscans, consisted of Gauls or Celts...

(58-51 BC). These commanded detachments of one or more legions at the governor's behest and played a critical role in the conquest of Gaul. But legions still lacked a single, permanent commander. This was provided by Augustus, who appointed a legatus to command each legion with a term of office of several years. The ranking senatorial military tribune (tribunus militum laticlavius) was designated deputy commander, while the remaining 5 equestrian tribunes served as the legatus' staff officers. In addition, Augustus established a new post of praefectus castrorum
Praefectus Castrorum
The praefectus castrorum was, in the Roman army of the early Empire, the third-most senior commander of the Roman legion, after the legate and the senior military tribune . His responsibility was looking after equipment and building works but could command the legion when his seniors were absent...

(literally "prefect of the camp"), to be filled by a Roman knight (often an outgoing centurio
Centurion
A centurion was a professional officer of the Roman army .Centurion may also refer to:-Military:* Centurion tank, British battle tank* HMS Centurion, name of several ships and a shore base of the British Royal Navy...

primus pilus, a legion's chief centurion, who was usually elevated to equestrian rank on completion of his single-year term of office). Technically, this officer ranked below the senatorial tribune, but his long operational experience made him the legion commander's de facto executive officer. The prefect's primary role was as the legion's quartermaster

Quartermaster

Quartermaster refers to two different military occupations depending on if the assigned unit is land based or naval.In land armies, especially US units, it is a term referring to either an individual soldier or a unit who specializes in distributing supplies and provisions to troops. The senior...

, in charge of legionary camps and supplies.

It has been suggested that Augustus was responsible for establishing the tiny cavalry contingent of 120 horse attached to each legion. The existence of this unit is attested in Josephus

Josephus

' Bellum Iudaicum written after AD 70, and on a number of tombstones. The attribution to Augustus is based on the (unproven) assumption that legionary cavalry had completely disappeared in the Caesarian army. The Augustan era also saw the introduction of some items of more sophisticated and protective equipment for legionaries, primarily to improve their survival rate. The lorica segmentata
Lorica segmentata
The lōrīca segmentāta was a type of segmented armour almost exclusively used in the Roman Empire, but the Latin name was first used in the 16th century...

(normally called simply "the lorica" by the Romans), was a special laminated-strip body-armour, was probably developed under Augustus. Its earliest depiction is on the Arch of Augustus at Susa (Western Alps), dating from 6 BC. The oval shield of the Republic was replaced by the convex rectangular shield (scutum
Scutum
Scutum is a small constellation introduced in the seventeenth century. Its name is Latin for shield.-History:Scutum is the only constellation that owes its name to a non-classical historical figure...

) of the imperial era.

Auxilia

Augustus' ambitious expansion plans for the Empire (which included advancing the European border to the lines of the Elbe

Elbe

The Elbe is one of the major rivers of Central Europe. It rises in the Krkonoše Mountains of the northwestern Czech Republic before traversing much of Bohemia , then Germany and flowing into the North Sea at Cuxhaven, 110 km northwest of Hamburg...

and Danube

Danube

The Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....

rivers) soon proved that 28 legions were not sufficient. Starting with the Cantabrian Wars

Cantabrian Wars

The Cantabrian Wars occurred during the Roman conquest of the modern provinces of Cantabria, Asturias and León, against the Asturs and the Cantabri. They were the final stage of the conquest of Hispania.-Antecedents:...

, which aimed to annex the mineral-rich mountains of north-western Spain, Augustus' 44-year sole rule saw an almost uninterrupted series of major wars that frequently stretched the army's manpower to the limit.

Augustus retained the services of numerous units of irregular allied native troops. But there was an urgent need for extra regular troops, organised, if not yet equipped, in the same way as the legions. These could only be drawn from the Empire's vast pool of non-citizen subjects, known as peregrini
Peregrinus (Roman)
Peregrinus was the term used during the early Roman empire, from 30 BC to 212 AD, to denote a free provincial subject of the Empire who was not a Roman citizen. Peregrini constituted the vast majority of the Empire's inhabitants in the 1st and 2nd centuries AD...

. These outnumbered Roman citizens by around 9 to 1 in the early 1st century. The peregrini were now recruited into regular units of cohort

Cohort (military unit)

A cohort was the basic tactical unit of a Roman legion following the reforms of Gaius Marius in 107 BC.-Legionary cohort:...

-strength (ca. 500 men), to form a non-citizen corps called the auxilia (literally: "supports"). By AD 23, Tacitus reports that the auxilia numbered roughly as many as the legionaries (i.e. ca. 150,000 men). The roughly 250 regiments of auxilia this implies were divided into 3 types: an all-infantry cohors (plural: cohortes) (cohort

Cohort (military unit)

A cohort was the basic tactical unit of a Roman legion following the reforms of Gaius Marius in 107 BC.-Legionary cohort:...

) (ca. 120 regiments); an infantry unit with a cavalry contingent attached, the cohors equitata (plural: cohortes equitatae) (80 units); and an all-cavalry ala (plural: alae, literal meaning: "wing"), of which ca. 50 were originally established.

It appears that at this early stage, auxiliary recruitment was ethnically based, with most men originating from the same tribe or province. Hence regiments carried an ethnic name e.g. cohors V Raetorum ("5th Cohort of Raeti"), recruited from the Raeti

Raeti

The Raeti was the collective "ethnic" name used by the ancient Romans to denote a number of Alpine tribes, whose language and culture may have derived, at least in part, from the Etruscans. From not later than ca...

, a group of Alpine

Alps

The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....

tribes that inhabited modern Switzerland. It has been suggested that the equipment of auxiliary regiments was not standardised until after AD 50, and that until then, auxiliaries were armed with the traditional weaponry of their tribe. But it is possible that at least some regiments had standardised equipment from Augustan times.

Auxiliary regiments were designed to operate as a complement to the legions. That is, they performed exactly the same role as the Republic's alae of Italian allies (socii) before the Social War (91-88 BC), an equal number of which always accompanied legions on campaign.

Praetorian Guard

Under the late Republic, a proconsul on campaign often formed a small personal guard, selected from the troops under his command, known as a cohors praetoria ("commander's cohort"), from praetorium
Praetorium
- Etemology :The praetorium, also spelled prœtorium or pretorium, was originally used to identify the general’s tent within a Roman Castra, Castellum, or encampment. The word originates from the name of the chief Roman magistrate, known as Praetor...

meaning the commander's tent at the centre of a Roman marching-camp (or commander's residence in a legionary fortress). At the Battle of Actium

Battle of Actium

The Battle of Actium was the decisive confrontation of the Final War of the Roman Republic. It was fought between the forces of Octavian and the combined forces of Mark Antony and Cleopatra VII. The battle took place on 2 September 31 BC, on the Ionian Sea near the city of Actium, at the Roman...

(31 BC), Augustus had 5 such cohorts around him. After the battle, he retained them in being as a permanent brigade in and around Rome, known as the praetoriani ("soldiers of the imperial palace"). Inscription evidence suggests that Augustus increased the praetorian establishment to 9 cohorts, each under the command of a tribunus militum (military tribune). With all the legions deployed in far-off provinces under the command of powerful senators, Augustus evidently considered that he needed a least one legion-sized force with him in Rome to deter potential usurpers. Augustus stationed 3 cohorts in the City itself, each housed in separate barracks, and the rest in neighbouring cities of Latium

Latium

Lazio is one of the 20 administrative regions of Italy, situated in the central peninsular section of the country. With about 5.7 million residents and a GDP of more than 170 billion euros, Lazio is the third most populated and the second richest region of Italy...

. Originally, each cohort was independent, but in 2 BC, Augustus appointed two overall commanders (praefecti praetorio) of equestrian rank, one for the cohorts based in the City, the other for those outside.

The praetorians were envisaged as an elite force, whose duty was to guard the imperial palace on the Palatine hill

Palatine Hill

The Palatine Hill is the centermost of the Seven Hills of Rome and is one of the most ancient parts of the city...

, protect the Emperor's person and those of his family, defend the imperial government, and to accompany the emperor when he left the City on long journeys or to lead military campaigns in person. They were also to serve as ceremonial troops on state occasions. Recruits to the ranks were exclusively Italians. They were accorded much better pay and conditions than ordinary legionaries. In AD 5, the standard term of service for praetorians was set at 16 years (compared to 25 years in the legions), and praetorians' pay was set at triple that of ordinary legionaries. In order to avoid the impression of a military occupation of the capital, Augustus laid down a rule that praetorians on duty within the city boundaries must not wear armour and must keep their weapons out of sight. Those praetorians on important official duties, such as the Emperor's bodyguard-detail, wore the formal dress of Roman citizens, the toga

Toga

The toga, a distinctive garment of Ancient Rome, was a cloth of perhaps 20 ft in length which was wrapped around the body and was generally worn over a tunic. The toga was made of wool, and the tunic under it often was made of linen. After the 2nd century BC, the toga was a garment worn...

, under which they concealed their swords and daggers. The rest wore the soldier's standard non-combat dress of tunic and cloak (paludamentum).

Augustus' successor Tiberius

Tiberius

Tiberius , was Roman Emperor from 14 AD to 37 AD. Tiberius was by birth a Claudian, son of Tiberius Claudius Nero and Livia Drusilla. His mother divorced Nero and married Augustus in 39 BC, making him a step-son of Octavian...

(r. 14-37), appointed only single commanders to the Guard: Sejanus 14-31, and, after ordering the latter's execution for treason, Macro

Naevius Sutorius Macro

Quintus Naevius Cordus Sutorius Macro was a prefect of the Praetorian Guard, from 31 until 38, serving under the Roman Emperors Tiberius and Caligula...

. Under the influence of Sejanus, who also acted as his chief political advisor, Tiberius decided to concentrate the accommodation of all the praetorian cohorts into a single, purpose-built fortress of massive size on the outskirts of Rome, beyond the Servian Wall

Servian Wall

The Servian Wall was a defensive barrier constructed around the city of Rome in the early 4th century BC. The wall was up to 10 metres in height in places, 3.6 metres wide at its base, 11 km long, and is believed to had 16 main gates, though many of these are mentioned only from...

. Known as the castra praetoria
Castra Praetoria
Castra Praetoria were the ancient barracks of the Praetorian Guard of Imperial Rome.-History:According to the Roman historian Suetonius, the barracks were built in 23 AD by Lucius Aelius Sejanus, the praetorian prefect serving under the emperor Tiberius, in an effort to consolidate the several...

("praetorian camp"), its construction was complete by AD 23.

Urban cohorts

In addition to the praetorians, Augustus established a second armed force in Rome, the cohortes urbanae ("urban cohorts"), of which 3 were based in the City and one in Lugdunum
Lugdunum
Colonia Copia Claudia Augusta Lugdunum was an important Roman city in Gaul. The city was founded in 43 BC by Lucius Munatius Plancus. It served as the capital of the Roman province Gallia Lugdunensis. To 300 years after its foundation Lugdunum was the most important city to the west part of Roman...

(Lyon) in Gaul, to protect the major imperial mint

Mint (coin)

A mint is an industrial facility which manufactures coins for currency.The history of mints correlates closely with the history of coins. One difference is that the history of the mint is usually closely tied to the political situation of an era...

there. These battalions were tasked with maintaining public order in the City, including crowd-control at major events such as chariot-races and gladiator

Gladiator

A gladiator was an armed combatant who entertained audiences in the Roman Republic and Roman Empire in violent confrontations with other gladiators, wild animals, and condemned criminals. Some gladiators were volunteers who risked their legal and social standing and their lives by appearing in the...

ial combats, and the suppression of the popular unrest that periodically shook the City e.g. the riots caused by high grain prices in AD 19. Their command was given to the praefectus urbi
Praefectus urbi
The praefectus urbanus or praefectus urbi, in English the urban prefect, was prefect of the city of Rome, and later also of Constantinople. The office originated under the Roman kings, continued during the Republic and Empire, and held high importance in late Antiquity...

, a senator who acted as Rome's "mayor". Unlike the praetorians, the urban cohorts were not deployed for military operations outside Italy.

German bodyguards

To double-insure his own personal safety and that of imperial family members, Augustus established a small personal guard called the Germani corporis custodes ("German bodyguard unit"). Probably of cohort-strength, these were crack horsemen recruited from native peoples on the lower Rhine, mainly from the Batavi. Their leader, probably a Batavi aristocrat, answered to the Emperor alone. The Germans shared the task of guarding the imperial palace and family with the praetorians. In AD 68, the Emperor Galba

Galba

Galba , was Roman Emperor for seven months from 68 to 69. Galba was the governor of Hispania Tarraconensis, and made a bid for the throne during the rebellion of Julius Vindex...

disbanded the German bodyguard unit because of their loyalty to Nero

Nero

(ruled 54-68), whom he had overthrown. The decision caused deep offence to the Batavi, and contributed to the outbreak of the Revolt of the Batavi in the following year.

Imperial expansion and stasis

Under Augustus, the long-term borders of the empire became largely settled. Augustus' main strategic aim was to advance the European Roman border from Dalmatia

Dalmatia

Dalmatia is a historical region on the eastern coast of the Adriatic Sea. It stretches from the island of Rab in the northwest to the Bay of Kotor in the southeast. The hinterland, the Dalmatian Zagora, ranges from fifty kilometers in width in the north to just a few kilometers in the south....

and Macedonia

Macedonia (Roman province)

The Roman province of Macedonia was officially established in 146 BC, after the Roman general Quintus Caecilius Metellus defeated Andriscus of Macedon, the last Ancient King of Macedon in 148 BC, and after the four client republics established by Rome in the region were dissolved...

to the line of the Danube

Danube

The Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....

, both to increase strategic depth between the border and Italy and to provide a major fluvial supply route for the Roman armies in the region. To this end, Moesia

Moesia

Moesia was an ancient region and later Roman province situated in the Balkans, along the south bank of the Danube River. It included territories of modern-day Southern Serbia , Northern Republic of Macedonia, Northern Bulgaria, Romanian Dobrudja, Southern Moldova, and Budjak .-History:In ancient...

(27 BC), Pannonia

Pannonia

Pannonia was an ancient province of the Roman Empire bounded north and east by the Danube, coterminous westward with Noricum and upper Italy, and southward with Dalmatia and upper Moesia....

(AD 9), Noricum

Noricum

Noricum, in ancient geography, was a Celtic kingdom stretching over the area of today's Austria and a part of Slovenia. It became a province of the Roman Empire...

(16 BC) and Raetia

Raetia

Raetia was a province of the Roman Empire, named after the Rhaetian people. It was bounded on the west by the country of the Helvetii, on the east by Noricum, on the north by Vindelicia, on the west by Cisalpine Gaul and on south by Venetia et Histria...

(15 BC) were annexed. Augustus predecessor Julius Caesar had already established the border of Gaul

Gaul

Gaul was a region of Western Europe during the Iron Age and Roman era, encompassing present day France, Luxembourg and Belgium, most of Switzerland, the western part of Northern Italy, as well as the parts of the Netherlands and Germany on the left bank of the Rhine. The Gauls were the speakers of...

along the Rhine, another major fluvial route. But Augustus initially aimed to advance that border to the Elbe

Elbe

, in order to pacify the many warlike Germanic tribes in between. But a massive military effort came to nothing as a result of the disastrous loss of 3 legions under Varus

Varus

-People:*Publius Attius Varus , Roman governor of Africa.*Publius Quinctilius Varus , politician of the Roman Empire.*Quinctilius Varus -People:*Publius Attius Varus (died 17 March 45 BCE), Roman governor of Africa.*Publius Quinctilius Varus (46 BCE - 9 CE), politician of the Roman...

in AD 9, after which the expansion plans were shelved and never seriously revived (although parts of trans-Rhenine Germany such as the Agri Decumates
Agri Decumates
The agri decumates or decumates agri were a region of the Roman Empire's province of Germania superior , covering the Black Forest area between the Main river and the sources of Danube and Rhine rivers, presently in Southwestern Germany...

and the Main valley were later occupied by the Romans in various periods). The Rhine-Danube line became the permanent border of the Roman Empire in Europe. The only major efforts to advance beyond it were Trajan's annexation of Dacia

Dacia

In ancient geography, especially in Roman sources, Dacia was the land inhabited by the Dacians or Getae as they were known by the Greeks—the branch of the Thracians north of the Haemus range...

(101-6), but this was motivated not so much by the desire to expand the empire as to eliminate a dangerous rival in the form of Decebal's Dacian state and to seize control of Dacia's mineral resources (Dacia was eventually abandoned in 275); and the Emperor Marcus Aurelius' reported aim to annex "Sarmatia" (i.e. the Hungarian plain beyond the Danube) and "Marcomannia" (Bohemia) as a result of the Marcomannic Wars

Marcomannic Wars

The Marcomannic Wars were a series of wars lasting over a dozen years from about AD 166 until 180. These wars pitted the Roman Empire against the Marcomanni, Quadi and other Germanic peoples, along both sides of the upper and middle Danube...

(166-80) - but these plans were abandoned by Aurelius' son Commodus

Commodus

Commodus , was Roman Emperor from 180 to 192. He also ruled as co-emperor with his father Marcus Aurelius from 177 until his father's death in 180. His name changed throughout his reign; see changes of name for earlier and later forms. His accession as emperor was the first time a son had succeeded...

(180-92). In the East, despite occasional wars against the Parthian Empire

Parthian Empire

The Parthian Empire , also known as the Arsacid Empire , was a major Iranian political and cultural power in ancient Persia...

over buffer-states such as Armenia

Armenia

Armenia , officially the Republic of Armenia , is a landlocked mountainous country in the Caucasus region of Eurasia...

, the long-term border was settled along the upper Euphrates river and the Syrian desert. In North Africa, the Sahara

Sahara

The Sahara is the world's second largest desert, after Antarctica. At over , it covers most of Northern Africa, making it almost as large as Europe or the United States. The Sahara stretches from the Red Sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic Ocean...

desert provided a natural confine.

As the borders became settled, the Roman army gradually transformed from an army of conquest to one of strategic defence, with long-term, fortified bases along the major river supply routes for the legions, supported by permanent stone forts for the auxiliary regiments.

1st century

The dual-structure configuration of legions/auxilia established by Augustus remained essentially intact until the late 3rd century, with only minor modifications made during that long period. The senior officers of the army were, until the 3rd century, mainly from the Italian aristocracy. This was divided into two orders, the senatorial order (ordo senatorius), consisting of the ca. 600 sitting members of the Roman Senate

Roman Senate

The Senate of the Roman Republic was a political institution in the ancient Roman Republic, however, it was not an elected body, but one whose members were appointed by the consuls, and later by the censors. After a magistrate served his term in office, it usually was followed with automatic...

(plus their sons and grandsons), and the more numerous (several thousand-strong) equites equo publico or "knights granted a public horse" i.e. knights hereditary or appointed by the Emperor. Hereditary senators and knights combined military service with civilian posts, a career-path known as the cursus honorum
Cursus honorum
The cursus honorum was the sequential order of public offices held by aspiring politicians in both the Roman Republic and the early Empire. It was designed for men of senatorial rank. The cursus honorum comprised a mixture of military and political administration posts. Each office had a minimum...

, typically starting with a period of junior administrative posts in Rome, followed by 5 to 10 years in the military and a final period of senior positions in either the provinces or at Rome. This tiny, tightly knit ruling oligarchy of under 10,000 men monopolised political, military and economic power in an empire of ca. 60 million inhabitants and achieved a remarkable degree of political stability. During the first 200 years of its existence (30 BC – AD 180), the empire suffered only one major episode of civil strife (the Civil War of 68–9

Year of the Four Emperors

). Otherwise, attempts at usurpation by provincial governors were few and swiftly suppressed.

Under the emperor Claudius

Claudius

Claudius , was Roman Emperor from 41 to 54. A member of the Julio-Claudian dynasty, he was the son of Drusus and Antonia Minor. He was born at Lugdunum in Gaul and was the first Roman Emperor to be born outside Italy...

(ruled 41-54), a minimum term of 25 years' service was established for auxiliary service (although many served for longer). On completion of the term, auxiliary soldiers, and their children, were from this time routinely granted Roman citizenship as a reward for service. (This is deduced from the fact that the first known Roman military diplomas date from the time of Claudius. This was a folding bronze tablet engraved with the details of the soldier's service record, which he could use to prove his citizenship).

Claudius also decreed that prefects of auxiliary regiments must all be of knightly rank, thus excluding serving centurions from such commands. The fact that auxiliary commanders were now all of the same social rank as all but one of a legion's military tribunes, probably indicates that auxilia now enjoyed greater prestige. Indigenous chiefs continued to command some auxiliary regiments, and were normally granted the rank of Roman knight for the purpose.

It is also likely that auxiliary pay was standardised at this time, but pay scales during the Julio-Claudian period are uncertain. Estimates range from 33-50% of legionary pay, well below the 75-80% in force in the time of the emperor Domitian

Domitian

(ruled 81-96).

Auxiliary uniform, armour, weapons and equipment were probably standardised by the end of the Julio-Claudian period (AD 68). Auxiliary equipment was broadly similar to that of the legions. By AD 68, there was little difference between most auxiliary infantry and their legionary counterparts in equipment, training and fighting capability.

After about AD 80, the centuriae of the First Cohort of each legion were doubled in size to 160 men, but the number of centuriae apparently reduced to 5, thus reducing the legion's centurions from 60 to 59. The legion's effectives were thus increased to ca. 5,240 men plus officers. In the same period, some auxiliary regiments, both alae and cohortes, were also doubled to so-called milliaria size (literally "1,000-strong", actually only 720 in milliary alae and 800 in cohortes). But only a minority of auxiliary regiments, about 1 in 7, were so enlarged.

2nd century

During the 2nd century some units with the new names numerus ("group") and vexillatio ("detachment") appear in the diploma record. Their size is uncertain, but was likely smaller than the regular alae and cohortes, as originally they were probably detachments from the latter, acquiring independent status after long-term separation. As these units are mentioned in diplomas, they were presumably part of the regular auxiliary organisation. But numeri was also a generic term used for barbarian units outside the regular auxilia. (see section 2.4 Irregular units, below).

3rd century

The traditional alternation between senior civilian and military posts fell into disuse in the late 2nd and 3rd centuries, as the Italian hereditary aristocracy was progressively replaced in the senior echelons of the army by the primipilares (former chief centurions). In the 3rd century, only 10% of auxiliary prefects whose origins are known were Italian equestrians, compared to the majority in the previous two centuries. At the same time, equestrians increasingly replaced the senatorial order in the top commands. Septimius Severus

Septimius Severus

Septimius Severus , also known as Severus, was Roman Emperor from 193 to 211. Severus was born in Leptis Magna in the province of Africa. As a young man he advanced through the customary succession of offices under the reigns of Marcus Aurelius and Commodus. Severus seized power after the death of...

(ruled 197–211) placed equestrian primipilares in command of the three new legions he raised and Gallienus

Gallienus

Gallienus was Roman Emperor with his father Valerian from 253 to 260, and alone from 260 to 268. He took control of the Empire at a time when it was undergoing great crisis...

(260–68) did the same for all the other legions, giving them the title praefectus pro legato ("prefect acting as legate"). The rise of the primipilares may have provided the army with more professional leadership, but it increased military rebellions by ambitious generals. The 3rd century saw numerous coups d'état and civil wars. Few 3rd-century emperors enjoyed long reigns or died of natural causes.

Emperors responded to the increased insecurity with a steady build-up of the forces at their immediate disposal. These became known as the comitatus ("escort", from which derives the English word "committee"). To the Praetorian Guard's 10,000 men, Septimius Severus added the legion II Parthica
Legio II Parthica
Legio secunda Parthica was a Roman legion levied by Emperor Septimius Severus in 197, for his campaign against the Parthian Empire, hence the cognomen Parthica. The legion was still active in the beginning of the 5th century...

. Based at Albano Laziale

Albano Laziale

Albano Laziale is a comune in the province of Rome, on the Alban Hills, in Latium, central Italy. It is also a suburb of Rome, which is 25 km distant. It is bounded by other communes of Castel Gandolfo, Rocca di Papa, Ariccia and Ardea. Located in the Castelli Romani area of Lazio...

near Rome, it was the first legion to be stationed in Italy since Augustus. He doubled the size of the imperial escort cavalry, the equites singulares Augusti, to 2,000 by drawing select detachments from alae on the borders. His comitatus thus numbered some 17,000 men. The rule of Gallienus saw the appointment of a senior officer, with the title of dux equitum ("cavalry leader"), to command all the cavalry of the emperor's comitatus. This included equites promoti (cavalry contingents detached from the legions), plus Illyrian light cavalry (equites Dalmatarum) and allied barbarian cavalry (equites foederati). But the dux equitum did not command an independent "cavalry army", as was suggested by some more dated scholars. The cavalry remained integral to the mixed infantry- and cavalry-comitatus, with the infantry remaining the predominant element.

The seminal development for the army in the early 3rd century was the Constitutio Antoniniana
Constitutio Antoniniana
The Constitutio Antoniniana was an edict issued in 212 AD, by the Roman Emperor Caracalla...

(Antonine Decree) of 212, issued by Emperor Caracalla

Caracalla

Caracalla , was Roman emperor from 198 to 217. The eldest son of Septimius Severus, he ruled jointly with his younger brother Geta until he murdered the latter in 211...

(ruled 211–18). This granted Roman citizenship to all free inhabitants of the empire, ending the second-class status of the peregrini. This had the effect of breaking down the distinction between the citizen legions and the auxiliary regiments. In the 1st and 2nd centuries, the legions were the symbol (and guarantors) of the dominance of the Italian "master nation" over its subject peoples. In the 3rd century, they were no longer socially superior to their auxiliary counterparts (although they may have retained their elite status in military terms).

In tandem, the legions' special armour and equipment (e.g. the lorica segmentata
Lorica segmentata
The lōrīca segmentāta was a type of segmented armour almost exclusively used in the Roman Empire, but the Latin name was first used in the 16th century...

) was phased out during the early 3rd century. There was also a progressive reduction in the size of the legions. Legions were broken up into smaller units, as evidenced by the shrinkage and eventual abandonment of their traditional large bases, documented for example in Britain. In addition, from the 2nd century onwards, the separation of some detachments from their parent units became permanent in some cases, establishing new unit types, e.g. the vexillatio equitum Illyricorum based in Dacia in the early 2nd century and the equites promoti (legionary cavalry detached from their unit) and numerus Hnaufridi in Britain.

Army size and cost

The first global estimate for the size of the imperial army in the ancient sources is in the Annales
Annals (Tacitus)
The Annals by Tacitus is a history of the reigns of the four Roman Emperors succeeding Caesar Augustus. The surviving parts of the Annals extensively cover most of the reigns of Tiberius and Nero. The title Annals was probably not given by Tacitus, but derives from the fact that he treated this...

of Tacitus

Tacitus

. In AD 23, shortly after the end of the rule of Augustus, there were 25 legions (about 125,000 men) and "roughly the same number again of auxiliaries" in about 250 regiments.

From this base-line of ca. 250,000 effectives, the imperial army grew steadily in the 1st and 2nd centuries, almost doubling in size to ca. 450,000 by the end of the rule of Septimius Severus

Septimius Severus

(AD 211). The number of legions increased to a peak of 33, and auxiliary regiments even more sharply to over 400 regiments.

In the late 3rd century, it is likely that the army suffered a sharp decline in numbers due to the so-called "Third Century Crisis" (235-70) a period of numerous civil wars, major barbarian invasions and above all, the Plague of Cyprian

Plague of Cyprian

The Plague of Cyprian is the name given to a pandemic, probably of smallpox, that afflicted the Roman Empire from AD 250 onwards. It was still raging in 270, when it claimed the life of emperor Claudius II Gothicus . The plague caused widespread manpower shortages in agriculture and the Roman army....

, an outbreak of smallpox which may have eliminated as many as a third of the army's effectives. It is possible that, by AD 270, the army was not much greater than in AD 23. Finally, the emperor Diocletian

Diocletian

Diocletian |latinized]] upon his accession to Diocletian . c. 22 December 244 – 3 December 311), was a Roman Emperor from 284 to 305....

(ruled 284-305) apparently restored army numbers to the same level (390,000) as it had stood in about 130.

The likely trend in the size of the Roman army in the Principate may be summarised as follows:

ROMAN ARMY NUMBERS 24–305 AD
! Army corps !! Tiberius
*AD 24* !! Hadrian
*ca. AD 130* !! S. Severus
*AD 211* !! 3rd c. crisis
*ca. AD 270* !! Diocletian
*284–305*
LEGIONS	125,000	155,000	182,000
AUXILIA	125,000	218,000	250,000
PRAETORIAN GUARD	~~5,000	~10,000	~10,000
Total Roman Army	255,000	383,000	442,000	290,000?

Note: Figures are based on official (not actual) unit strengths and exclude Roman Navy

Roman Navy

The Roman Navy comprised the naval forces of the Ancient Roman state. Although the navy was instrumental in the Roman conquest of the Mediterranean basin, it never enjoyed the prestige of the Roman legions...

effectives (30-40,000 men) and barbarian foederati (at least 11,000).

It is estimated that the imperial fleets employed 30-40,000 personnel. Adding 10-20,000 barbarian foederati, the military establishment at the time of Severus numbered not far short of half a million men. The impact of the costs of this enormous standing army on the Roman economy can be measured very approximately.

ARMY COSTS AS SHARE OF ROMAN EMPIRE GDP
! Date !! Empire
population !! Empire GDP
(millions of *denarii*)^(a) !! Army costs
(millions of *denarii*)^(a) !! Army costs
as share of GDP
AD 14	46 millions	5,000	123	2.5%
AD 150	61 millions	6,800^(b)	194^(c)	2.9%
AD 215	50 millions^(d)	5,435^(b)	223^(c)	4.1%

Notes:

(a) constant AD 14 denarii i.e. disregarding increases in military pay to compensate for debasement of coinage

(b) assuming negligible growth in GDP per capita (normal for agricultural economy)

(c) Duncan-Jones 14-84 costs, inflated by increase in army nos. & assuming cash-bonuses and discharge-bonus paid to auxiliaries after 84

(d) assuming 22.5% decline in population due to Antonine Plague

Antonine Plague

The Antonine Plague, AD 165–180, also known as the Plague of Galen, who described it, was an ancient pandemic, either of smallpox or measles, brought back to the Roman Empire by troops returning from campaigns in the Near East...

(AD 165-80) (mid-point of 15-30% range)

Army costs thus rose only moderately as a share of GDP between 14 and 150 AD, despite a major increase in army effectives of ca. 50%. This is because the empire's population, and therefore total GDP, also increased substantially (by ca. 35%). Thereafter, the army's share of GDP leapt by almost half, although army numbers increased only ca. 15%. This is due to the Antonine plague, which is estimated by epidemiological historians to have reduced the empire's population by 15-30%. Nevertheless, even in 215, the Romans spent a similar proportion of GDP on defence than today's global superpower, the United States of America (which spent ca. 3.5% in 2003). But the effective burden on taxpayers in an unmechanised agricultural economy with little surplus production (80% of the population depended on subsistence agriculture

Subsistence agriculture

Subsistence agriculture is self-sufficiency farming in which the farmers focus on growing enough food to feed their families. The typical subsistence farm has a range of crops and animals needed by the family to eat and clothe themselves during the year. Planting decisions are made with an eye...

and a further 10% were on subsistence income), would have been relatively far heavier. Indeed, a study of imperial taxes in Egypt, by far the best-documented province, concluded that the burden was relatively severe.

Military spending swallowed up ca. 75% of total government budget, as there was little "social" spending, the main items of the latter consisting of prestige construction projects in Rome and the provinces; grain-dole and cash-handouts for Rome's proletariat; and subsidies to Italian families (similar to modern child benefit

Child benefit

Child benefit is a social security payment disbursed to the parents or guardians of children. Child benefit is means-tested in some countries.-Australia:...

), to encourage them to produce more children. Augustus instituted this policy, with a one-off payment of 250 denarii per child. (Additional subsidies to poor Italian families, known as alimenta, were introduced by Trajan).

Central command

Under the Augustan settlement, the Roman state formally remained a republic, with the same official name, Senatus Populusque Romanus (SPQR - "The Senate and People of Rome") and administered by the same magistrates

Roman Magistrates

The Roman Magistrates were elected officials in Ancient Rome. During the period of the Roman Kingdom, the King of Rome was the principal executive magistrate. His power, in practice, was absolute. He was the chief priest, lawgiver, judge, and the sole commander of the army...

(state executive officers) as before: the Consul

Roman consul

A consul served in the highest elected political office of the Roman Republic.Each year, two consuls were elected together, to serve for a one-year term. Each consul was given veto power over his colleague and the officials would alternate each month...

s (2 elected each year), Praetor

Praetor

Praetor was a title granted by the government of Ancient Rome to men acting in one of two official capacities: the commander of an army, usually in the field, or the named commander before mustering the army; and an elected magistratus assigned varied duties...

s (4), Aedile

Aedile

Aedile was an office of the Roman Republic. Based in Rome, the aediles were responsible for maintenance of public buildings and regulation of public festivals. They also had powers to enforce public order. There were two pairs of aediles. Two aediles were from the ranks of plebeians and the other...

s (12), Quaestor

Quaestor

A Quaestor was a type of public official in the "Cursus honorum" system who supervised financial affairs. In the Roman Republic a quaestor was an elected official whereas, with the autocratic government of the Roman Empire, quaestors were simply appointed....

s (20), who were elected (by the Senate after AD 14) annually, and the Censors (2), who were elected every 5 years. In practice, however, political and military power was concentrated in the hands of the emperor

Roman Emperor

The Roman emperor was the ruler of the Roman State during the imperial period . The Romans had no single term for the office although at any given time, a given title was associated with the emperor...

, whose official titles were princeps ("First Citizen") and Augustus. (In conversation, the emperor was normally addressed as "Caesar" and referred to in popular speech as imperator
Imperator
The Latin word Imperator was originally a title roughly equivalent to commander under the Roman Republic. Later it became a part of the titulature of the Roman Emperors as part of their cognomen. The English word emperor derives from imperator via Old French Empreur...

, a term which originally meant "supreme commander"). The emperor's supremacy was based on his assumption of two permanent and sweeping powers: the tribunicia potestas ("power of the tribune (of the plebs)"), which gave him control of the legislative body, the Senate

Roman Senate

(by giving him a veto over its decrees); and the imperium proconsulare maius (literally: "eminent proconsular command"), which made the emperor, in effect, the commander-in-chief of the armed forces (by subordinating to his command the provincial governors, who controlled the military forces in their province

Roman province

In Ancient Rome, a province was the basic, and, until the Tetrarchy , largest territorial and administrative unit of the empire's territorial possessions outside of Italy...

). In addition, the emperor frequently had himself elected as one of the Consuls or Censors. The latter post was especially useful, as it gave him the power to appoint (or remove) members from the roll of Senators and from the Order of Knights, the two aristocratic orders of imperial Rome, which filled all senior administrative and military positions.

In the border provinces where military units were mostly stationed (i.e. 15-17 of the 42 Hadrianic provinces), the governors mostly bore the title legatus Augusti pro praetore
Legatus Augusti pro praetore
A legatus Augusti pro praetore was the official title of the governor of some imperial provinces of the Roman Empire during the Principate era, normally the larger ones or those where legions were based...

, although in a few smaller provinces they were known as procurator or praefectus. The governors, who normally held office for 3 years, commanded all forces in their provinces, both legions and auxilia, as well as being the heads of the civil administration. The governors reported directly to the emperor - there were no intermediate levels of command. However, there are instances during the Principate where the governors of smaller provinces were subordinated to governors of larger neighbouring ones e.g. the praefectus (later procurator) of Judaea

Judaea (Roman province)

Judaea or Iudaea are terms used by historians to refer to the Roman province that extended over parts of the former regions of the Hasmonean and Herodian kingdoms of Israel...

was normally subordinate to the legatus Augusti of Syria

Syria (Roman province)

Syria was a Roman province, annexed in 64 BC by Pompey, as a consequence of his military presence after pursuing victory in the Third Mithridatic War. It remained under Roman, and subsequently Byzantine, rule for seven centuries, until 637 when it fell to the Islamic conquests.- Principate :The...

.

At Rome, there was no army general staff

German General Staff

in the modern sense of a permanent central group of senior staff-officers who would receive and analyse military intelligence and advise on strategy. Augustus established a formal consilium principis ("imperial council") of magistrates and leading senators in rotation to advise him on all state matters and to prepare draft-decrees for submission to the Senate. But the real decisions were made by a semi-formal group of senior officials and close friends, the amici principis ("friends of the emperor"), whose membership was chosen by himself and might vary from time to time. Under Tiberius, the amici superseded the formal consilium and became the effective governing body of the empire.

Several amici would have had extensive military experience, due to the traditional mixing of civilian and military posts by the Principate aristocracy. But there was no consilium specifically dedicated to military affairs. Commanders of the Praetorian Guard, especially if they did not share their command with a partner, might acquire a predominant influence in military decision-making and act as de facto military chief-of-staff e.g. Sejanus, who was sole commander of the Guard AD 14-31, most of the emperor Tiberius

Tiberius

' rule.

The emperor and his advisors relied almost entirely on reports from the 17-odd "military" governors for their intelligence on the security situation on the imperial borders. This is because a central military intelligence agency was never established. The imperial government did develop an internal security unit called the frumentarii
Frumentarii
Frumentarii acted as the secret service of the Roman Empire. There are two main sources of information about the frumentarii, inscriptions on gravestones and anecdotes where the actions of individual frumentarii are mentioned by historians. From what is known of the Frumentarii, they always worked...

. In military jargon, this term, literally meaning "grain-collectors" (from frumentum = "grain"), referred to detachments of soldiers detailed to forage food supplies for their units in the field. The term came to be applied to auxiliary soldiers seconded to the staff of the procurator Augusti
Procurator (Roman fiscal)
A Roman fiscal procurator was the chief financial officer of a province of the Roman Empire during the Principate era...

, the independent chief financial officer of a province, to assist in the collection of taxes (originally in kind as grain). Such soldiers frequently visited Rome, where they were accommodated in a dedicated building, as liaison with the administrators of the imperial treasury. At some point, probably under Hadrian (r. 117-38), a permanent military unit (numerus) of frumentarii was established. Based in Rome, it was under the command of a senior centurion, the princeps frumentariorum. According to Aurelius Victor

Aurelius Victor

Sextus Aurelius Victor was a historian and politician of the Roman Empire.Aurelius Victor was the author of a History of Rome from Augustus to Julian , published ca. 361. Julian honoured him and appointed him prefect of Pannonia Secunda...

, the frumentarii were set up "to investigate and report on potential rebellions in the provinces" (presumably by provincial governors) i.e. they performed the function of an imperial secret police (and became widely feared and detested as a result of their methods, which included assassination). Though doubtless well-informed about events in the border-provinces through their network of local agents and spies, it appears that the frumentarii never expanded beyond internal security to fulfil a systematic military intelligence role.

The lack of independent military intelligence, coupled with the slow speeds of communication, prevented the emperor and his consilium from exercising anything but the most general control over military operations in the provinces. Typically, a newly appointed governor would be given a broad strategic direction by the emperor, such as whether to attempt to annex (or abandon) territory on their province's borders or whether to make (or avoid) war with a powerful neighbour such as Parthia. For example, in Britain, the governor Gnaeus Julius Agricola

Gnaeus Julius Agricola

appears to have been given approval for a strategy of subjugating the whole of Caledonia

Caledonia

Caledonia is the Latinised form and name given by the Romans to the land in today's Scotland north of their province of Britannia, beyond the frontier of their empire...

(Scotland) by Vespasian, only to have his gains abandoned by Domitian after AD 87, who needed reinforcements on the Danube front, which was threatened by the Sarmatians and Dacians. However, within these broad guidelines, the governor had almost complete autonomy of military decision-making.

Provincial command

In those provinces that contained military forces, the governor's immediate subordinates were the commanders (legati legionis) in command of the legions stationed in the province (e.g. in Britain, 3 legati reported to the governor). In turn, the legionary commander was reported to by the combat-unit commanders: the centuriones pili priores in command of the legion's cohorts and the praefecti, in command of the auxiliary regiments attached to the legion. The empire's high command structure was thus remarkably flat, with only 4 reporting levels between combat-unit commanders and the emperor.

An auxiliary regiment would normally, but not always, be attached to a legion for operational purposes, with the praefectus under the command of the legatus legionis
Legatus legionis
Legatus legionis was a title awarded to legion commanders in Ancient Rome.-History:By the time of the Roman Republic, the term legatus delegated authority...

(the legion's commander). The period that it was so attached could be a long one e.g. the 8 Batavi cohortes apparently attached to legion XIV Gemina

Legio XIV Gemina

Legio quarta decima Gemina was a legion of the Roman Empire, levied by Julius Caesar in late 58 B.C. The cognomen Gemina suggests that the legion resulted from fusion of two previous ones, one of them being the Fourteenth legion that fought in the Battle of Alesia, the other being the Martia ...

for the 26 years from the invasion of Britain in AD 43; to the Civil War of 69. However, a legion had no standard, permanent complement of auxilia. Its attached auxiliary units were changed and varied in number according to operational requirements at the behest of the governor of the province where the legion was based at the time or of the emperor in Rome.

Praetorian Guard

By AD 23, there were 9 praetorian cohorts in existence. These were probably the same size as legionary cohorts (480 men each), for a total of 4,320 effectives. Each cohort was under the command of a military tribune, normally a former chief centurion of a legion. It appears that each cohort contained some 90 cavalrymen who, like legionary cavalry were members of infantry centuriae, but operated in the field as 3 turmae of 30 men each.

The number of praetorian cohorts were increased to 12 by the time of Claudius. During the 68-9 civil war, Vitellius

Vitellius

Vitellius , was Roman Emperor for eight months, from 16 April to 22 December 69. Vitellius was acclaimed Emperor following the quick succession of the previous emperors Galba and Otho, in a year of civil war known as the Year of the Four Emperors...

disbanded the existing cohorts because he did not trust their loyalty and recruited 16 new ones, all double-strength (i.e. containing 800 men each). However, Vespasian

Vespasian

Vespasian , was Roman Emperor from 69 AD to 79 AD. Vespasian was the founder of the Flavian dynasty, which ruled the Empire for a quarter century. Vespasian was descended from a family of equestrians, who rose into the senatorial rank under the Emperors of the Julio-Claudian dynasty...

(r. 69-79) reduced the number of cohorts back to the original 9 (but still 800-strong), later increased to 10 by his son, Domitian

Domitian

(r. 81-96). By this time, therefore, the Guard consisted of ca. 8,000 men.

It was probably Trajan

Trajan

(r. 98-117) who established a separate cavalry arm of the Guard, the equites singulares Augusti
Equites singulares Augusti
The equites singulares Augusti during the Principate period of imperial Rome. Based in Rome, they escorted the Roman emperor whenever he left the City on campaign or on tours of the provinces.The regiment was reconstituted in the late 1st century AD as a milliary ala, under the command of a...

("personal cavalry of the emperor", or imperial horseguards). An elite troop recruited from members of the finest auxiliary alae (originally from Batavi alae only), the singulares were tasked with escorting the emperor on campaign. The unit was organised as a milliary ala, probably containing 720 horsemen. It was under the command of a military tribune, who probably reported to one of the praetorian prefects. It was the only praetorian regiment that admitted persons who were not natural-born citizens, although recruits appear to have been granted citizenship on enlistment and not on completion of 25 years' service as for other auxiliaries. The unit was housed in its own barracks on the Caelian hill

Caelian Hill

The Caelian Hill is one of the famous Seven Hills of Rome. Under reign of Tullus Hostilius, the entire population of Alba Longa was forcibly resettled on the Caelian Hill...

, separate from the main castra praetoria. By the time of Hadrian

Hadrian

(r.117-38), the singulares appear to heve numbered 1,000 men. They were further expanded to 2,000 horse in the early 3rd century by Septimius Severus, who constructed a new, larger base for them in Rome, the castra nova equitum singularium
Castra Nova equitum singularium
The Castra Nova equitum singularium was an ancient Roman fort in Rome housing part of the emperor's cavalry bodyguard. The site of the fort now lies beneath the Basilica of St John Lateran....

. By AD 100, therefore, the Guard consisted of ca. 9,000 effectives, rising to ca. 10,000 under Severus.

Some historians have dismissed the Guard as a parade-ground army of little military value. The praetorians were certainly taunted as such by the soldiers of the Danubian legions during the civil war of 68-9. But Rankov argues that the praetorians boasted a distinguished campaign-record that shows that their training and military effectiveness was far more impressive than those of merely ceremonial troops, sufficient to justify their elite status. During the Julio-Claudian era (to 68), the praetorians saw relatively little action in the field, as emperors only rarely led their armies in person. After that date, emperors led armies, and therefore deployed the praetorians on campaign, much more frequently. The praetorians were in the thick of the Emperor Domitian's wars, firstly in Germany and then on the Dacian front, where their prefect, Cornelius Fuscus

Cornelius Fuscus

Cornelius Fuscus was a Roman general who fought campaigns under the Emperors of the Flavian dynasty. During the reign of Domitian, he served as prefect of the imperial bodyguard, known as the Praetorian Guard, from 81 until his death in 86...

was killed in action (87). Other examples include the praetorians' prominent role in Trajan's Dacian Wars (101-6), as acknowledged on the friezes of Trajan's Column

Trajan's Column

and the Adamklissi Tropaeum

Tropaeum Traiani

The Tropaeum Traiani is a monument in Roman Civitas Tropaensium , built in 109 in then Moesia Inferior, to commemorate Roman Emperor Trajan's victory over the Dacians, in 102, in the Battle of Tapae. The monument was erected on the place where legio XXI Rapax had previously been defeated in 92...

. Equally celebrated, on the Column of Marcus Aurelius

Column of Marcus Aurelius

The Column of Marcus Aurelius is a Roman victory column in Piazza Colonna, Rome, Italy. It is a Doric column featuring a spiral relief: it was built in honour of Roman emperor Marcus Aurelius and modeled on Trajan's Column.- Construction :...

, was the praetorians' role in the Marcomannic Wars

Marcomannic Wars

(166-80), in which two Guard prefects lost their lives. Even their final hour was wreathed in military glory: at the Battle of the Milvian Bridge (312), the praetorians fought fiercely to prevent the army of Constantine I

Constantine I

Constantine the Great , also known as Constantine I or Saint Constantine, was Roman Emperor from 306 to 337. Well known for being the first Roman emperor to convert to Christianity, Constantine and co-Emperor Licinius issued the Edict of Milan in 313, which proclaimed religious tolerance of all...

from crossing the river Tiber

Tiber

The Tiber is the third-longest river in Italy, rising in the Apennine Mountains in Emilia-Romagna and flowing through Umbria and Lazio to the Tyrrhenian Sea. It drains a basin estimated at...

and entering Rome. Many perished fighting and others drowned with their emperor Maxentius

Maxentius

Maxentius was a Roman Emperor from 306 to 312. He was the son of former Emperor Maximian, and the son-in-law of Emperor Galerius.-Birth and early life:Maxentius' exact date of birth is unknown; it was probably around 278...

when the makeshift pontoon-bridge they were using collapsed. Subsequently, the praetorians paid the price of supporting the losing side: they were definitively disbanded, and their fortress demolished, by Constantine.

Legions

The legion consisted almost entirely of heavy infantry i.e. infantry equipped with metal armour (helmets and cuirasses). Although it was almost unbeatable by non-Roman infantry on the battlefield, it was a large, inflexible unit that could not campaign independently due to the lack of cavalry cover and other specialist forces. It was dependent on the support of auxiliary regiments.

The legion's basic sub-unit was the centuria
Centuria
Centuria is a Latin substantive from the stem centum , denoting units consisting of 100 men. It also denotes a Roman unit of land area: 1 centuria = 100 heredia...

(plural: centuriae), which literally means "a hundred men", but in practice numbered 80 men in the Principate, equivalent in numbers to a modern company

Company (military unit)

A company is a military unit, typically consisting of 80–225 soldiers and usually commanded by a Captain, Major or Commandant. Most companies are formed of three to five platoons although the exact number may vary by country, unit type, and structure...

. The legion's main tactical sub-unit was the cohors (plural: cohortes, or cohort

Cohort (military unit)

A cohort was the basic tactical unit of a Roman legion following the reforms of Gaius Marius in 107 BC.-Legionary cohort:...

), which contained 6 centuriae for a total of 480 men, roughly the same size as a modern battalion

Battalion

A battalion is a military unit of around 300–1,200 soldiers usually consisting of between two and seven companies and typically commanded by either a Lieutenant Colonel or a Colonel...

. There were 10 cohorts to each legion, or 4,800 men (ca. 5,000 including the small legionary cavalry of 120 horse and officers). Thus a legion was equivalent in numbers to a modern brigade

Brigade

A brigade is a major tactical military formation that is typically composed of two to five battalions, plus supporting elements depending on the era and nationality of a given army and could be perceived as an enlarged/reinforced regiment...

. By AD 100, however, the legion's First Cohort was divided into only 5 centuriae, but double-strength at 160 men each, for a total of 800 men. At this point, therefore, a legion would have numbered ca. 5,300 effectives.

In addition, each legion contained a small cavalry contingent of 120 men. Unlike auxiliary cavalry, however, they do not appear to have been organised in separate cavalry squadrons (turmae) as were auxiliary cavalry, but to have been divided among specific centuriae. Legionary cavalry probably performed a non-combat role as messengers, scouts and escorts for senior officers.

Auxilia

The following table sets out the official, or establishment, strength of auxiliary units in the 2nd century. The real strength of a unit would fluctuate continually, but would likely have been somewhat less than the establishment most of the time.

ROMAN AUXILIARY REGIMENTS: TYPE, STRUCTURE AND STRENGTH
! Unit type !! Service !! Unit
commander !! Sub-unit
commander !! No of
sub-units !! Sub-unit
strength !! Unit
strength
Ala Ala (Roman military) An Ala was the term used during the mid- Roman Republic to denote a military formation composed of conscripts from the socii, Rome's Italian military allies. A normal consular army during this period consisted of 2 legions, composed of Roman citizens only, and 2 allied alae... quingenaria	cavalry	praefectus	decurio Decurio Decurio was an official title in Ancient Rome, used in various connections:# A member of the senatorial order in the Italian towns under the administration of Rome, and later in provincial towns organized on the Italian model . The number of decuriones varied in different towns, but was usually 100...	16 turmae	30 (32)¹	480 (512)
Ala Ala (Roman military) An Ala was the term used during the mid- Roman Republic to denote a military formation composed of conscripts from the socii, Rome's Italian military allies. A normal consular army during this period consisted of 2 legions, composed of Roman citizens only, and 2 allied alae... milliaria	cavalry	praefectus	decurio	24 turmae	30 (32)	720 (768)
Cohors quingenaria	infantry	praefectus²	centurio Centurion A centurion was a professional officer of the Roman army .Centurion may also refer to:-Military:* Centurion tank, British battle tank* HMS Centurion, name of several ships and a shore base of the British Royal Navy...	6 centuriae	80	480
Cohors milliaria	infantry	tribunus militum Tribune Tribune was a title shared by elected officials in the Roman Republic. Tribunes had the power to convene the Plebeian Council and to act as its president, which also gave them the right to propose legislation before it. They were sacrosanct, in the sense that any assault on their person was... ³	centurio	10 centuriae	80	800
Cohors equitata quingenaria	infantry plus cavalry contingent	praefectus	centurio (inf) decurio (cav)	6 centuriae 4 turmae	80 30.	600 (480 inf/120 cav)
Cohors equitata milliaria	infantry plus cavalry contingent	tribunus militum³	centurio (inf) decurio (cav)	10 centuriae 8 turmae	80 30	1,040 (800 inf/240 cav)

Notes

(1) Opinion is divided about the size of an ala turma, between 30 and 32 men. A turma numbered 30 in the Republican cavalry and in the cohors equitata of the Principate auxilia. Against this is a statement by Arrian

Arrian

that an ala was 512 strong. This would make an ala turma 32 men strong.

(2) tribunus militum in original citizen cohortes

(3) praefectus in Batavi and Tungri cohortes milliariae

Unless the regiment name, was qualified by a specialist function e.g. cohors sagittariorum ("cohort of archers"), its infantry and cavalry were heavily equipped in the same way as the legionaries.

Cohors

These all-infantry units were modelled on the cohorts of the legions, with the same officers and sub-units. It is a common misconception that auxiliary cohortes contained light infantry: this only applies to specialist units such as archers. Their defensive equipment of regular auxiliary infantry was very similar to that of legionaries, consisting of metal helmet and metal cuirass (chain-mail or scale). There is no evidence that auxiliaries were equipped with the lorica segmentata
Lorica segmentata
The lōrīca segmentāta was a type of segmented armour almost exclusively used in the Roman Empire, but the Latin name was first used in the 16th century...

, the elaborate and expensive laminated-strip body-armour that was issued to legionaries. However, legionaries often wore chain-mail ans scalar cuirasses also. In addition, it appears that auxiliaries carried a round shield (clipeus) instead of the curved rectangular shield (scutum) of legionaries. As regards weapons, auxiliaries were equipped in the same way as legionaries: a javelin (although not the sophisticated pilum
Pilum
The pilum was a javelin commonly used by the Roman army in ancient times. It was generally about two metres long overall, consisting of an iron shank about 7 mm in diameter and 60 cm long with pyramidal head...

type provided to legionaries), a gladius (short stabbing-sword) and pugio (dagger). It has been estimated that the total weight of auxiliary
infantry equipment was similar to that of legionaries', so that non-specialist cohortes may also be classified as heavy infantry, which fought in the battle-line alongside legionaries.

There is no evidence that auxiliary infantry fought in a looser order than legionaries. It appears that in a set-piece battle-line, auxiliary infantry would normally be stationed on the flanks, with legionary infantry holding the centre e.g. as in the Battle of Watling Street

Battle of Watling Street

The Battle of Watling Street took place in Roman-occupied Britain in AD 60 or 61 between an alliance of indigenous British peoples led by Boudica and a Roman army led by Gaius Suetonius Paulinus. Although outnumbered, the Romans decisively defeated the allied tribes, inflicting heavy losses on them...

(AD 60), the final defeat of the rebel Britons under queen Boudicca

Boudica

Boudica , also known as Boadicea and known in Welsh as "Buddug" was queen of the British Iceni tribe who led an uprising against the occupying forces of the Roman Empire....

. This was a tradition inherited from the Republic, when the precursors of auxiliary cohortes, the Latin alae, occupied the same position in the line. The flanks of the line required equal, if not greater, skill to hold as the centre.

Ala

The all-mounted alae contained the elite cavalry of the Roman army. They were specially trained in elaborate manoeuvres, such as those displayed to the emperor Hadrian during a documented inspection. They were best-suited for large-scale operations and battle, during which they acted as the primary cavalry escort for the legions, which had almost no cavalry of their own. They were heavily protected, with chain-mail or scale body armour, a cavalry version of the infantry helmet (with more protective features) and oval shield. Their offensive weapons included a spear (hasta
Hasta (spear)
Hasta is a Latin word meaning spear. Hastae were carried by early Roman Legionaries, in particular they were carried by and gave their name to those Roman soldiers known as Hastati...

), a cavalry sword (spatha
Spatha
The spatha was a type of straight sword, measuring between , in use throughout first millennium AD Europe, and in the territory of the Roman Empire until about 600 AD. Later swords from 600 AD to 1000 AD are recognizable derivatives, though they are not spathae.The spatha was used in gladiatorial...

), which was much longer than the infantry gladius to provide greater reach and a long dagger. The elite status of an alaris is shown by the fact that he received 20% greater pay than his counterpart in a cohort, and than a legionary infantryman.

Cohors equitata

These were cohortes with a cavalry contingent attached. There is evidence that their numbers expanded with the passage of time. Only about 40% of attested cohortes are specifically attested as equitatae in inscriptions, which is probably the original Augustan proportion. A study of units stationed in Syria in the mid 2nd century found that many units which did not carry the equitata title did in fact contain cavalrymen e.g. by discovery of a tombstone of a cavalryman attached to the cohort. This implies that by that time, at least 70% of cohortes were probably equitatae. The addition of cavalry to a cohort obviously enabled it to carry out a wider range of independent operations. A cohors equitata was in effect a self-contained mini-army.

The traditional view of equites cohortales (the cavalry arm of cohortes equitatae), as expounded by G.L. Cheesman, was that they were just a mounted infantry with poor-quality horses. They would use their mounts simply to reach the battlefield and then would dismount to fight. This view is today discredited. Although it is clear that equites cohortales did not match equites alares (ala cavalrymen) in quality (hence their lower pay), the evidence is that they fought as cavalry in the same way as the alares and often alongside them. Their armour and weapons were the same as for the alares.

Nevertheless, non-combat roles of the equites cohortales differed significantly from the alares. Non-combat roles such as despatch-riders (dispositi) were generally filled by cohort cavalry.

Auxiliary specialised units

In the Republican period, the standard trio of specialised auxilia were Balearic slingers, Cretan archers and Numidian light cavalry. These functions, plus some new ones, continued in the 2nd century auxilia.

Heavily armoured lancers

Equites cataphractarii
Equites cataphractarii
Equites cataphractarii, or simply cataphractarii for short, were the heavily-armoured cavalry of the Imperial Roman army.Modelled on the cataphracts of Parthia, they were covered from neck-to-toe by lamellar armour , and normally armed with a contus, a long lance held in both hands, although...

, or simply cataphractarii for short, were the heavily armoured cavalry of the Roman army

Roman army

The Roman army is the generic term for the terrestrial armed forces deployed by the kingdom of Rome , the Roman Republic , the Roman Empire and its successor, the Byzantine empire...

. Based on Sarmatian

Sarmatians

The Iron Age Sarmatians were an Iranian people in Classical Antiquity, flourishing from about the 5th century BC to the 4th century AD....

and Parthia

Parthia

Parthia is a region of north-eastern Iran, best known for having been the political and cultural base of the Arsacid dynasty, rulers of the Parthian Empire....

n models, they were also known as contarii and clibanarii
Clibanarii
The Clibanarii or Klibanophoroi were a Sassanid Persian, late Roman and Byzantine military unit of heavy armored horsemen. Similar to the cataphracti, the horsemen themselves and their horses were fully armoured...

, although it is unclear whether these terms were interchangeable or whether they denoted variations in equipment or role. Together with new units of light mounted archers, the cataphractarii were designed to counter Parthian (and, in Pannonia

Pannonia

Pannonia was an ancient province of the Roman Empire bounded north and east by the Danube, coterminous westward with Noricum and upper Italy, and southward with Dalmatia and upper Moesia....

, Sarmatian) battle tactics. Parthian armies consisted largely of cavalry. Their standard tactic was to use light mounted archers to weaken and break up the Roman infantry line, and then to rout it with a charge by the cataphractarii concentrated on the weakest point. The only special heavy cavalry units to appear in the 2nd century record are: ala I Ulpia contariorum and ala I Gallorum et Pannoniorum cataphractaria stationed in Pannonia and Moesia Inferior respectively in the 2nd century.

Light cavalry

From the Second Punic War until the 3rd century AD, the bulk of Rome's light cavalry (apart from mounted archers from Syria) was provided by the inhabitants of the northwest African provinces of Africa proconsularis and Mauretania

Mauretania Caesariensis

Mauretania Caesariensis was a Roman province located in northwestern Africa. It was the easternmost of the North African Roman provinces, mainly in present Algeria, with its capital at Caesarea , now Cherchell.-Historical background:In the first century AD, Roman...

, the Numidae or Mauri (from whom derives the English term "Moors"), who were the ancestors of the Berber

Berber mythology

The traditional Berber mythology is the ancient and native set of beliefs and deities developed by the Berber people in their historical land of North Africa...

people of modern Algeria

Algeria

Algeria , officially the People's Democratic Republic of Algeria , also formally referred to as the Democratic and Popular Republic of Algeria, is a country in the Maghreb region of Northwest Africa with Algiers as its capital.In terms of land area, it is the largest country in Africa and the Arab...

and Morocco

Morocco

Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

. They were known as the equites Maurorum
Numidian cavalry
Numidian cavalry was a type of light cavalry developed by the Numidians, most notably used by Hannibal during the Second Punic War. They were described by the Roman historian Livy as "by far the best horsemen in Africa."...

or Numidarum ("Moorish or Numidian cavalry"). On Trajan's Column, Mauri horsemen, depicted with long hair in dreadlocks, are shown riding their small but resilient horses bare-back and unbridled, with a simple braided rope round their mount's neck for control. They wear no body or head armour, carrying only a small, round leather shield. Their weaponry cannot be discerned due to stone erosion, but is known from Livy to have consisted of several short javelins. Exceptionally fast and manoeuvrable, Numidian cavalry would harass the enemy by hit-and-run attacks, riding up and loosing volleys of javelins, then scattering faster than any opposing cavalry could pursue. They were superbly suited to scouting, harassment, ambush and pursuit, but in melee combat were vulnerable to cuirassiers. It is unclear what proportion of the Numidian cavalry were regular auxilia units as opposed to irregular foederati units.

In the 3rd century, new formations of light cavalry appear, apparently recruited from the Danubian provinces: the equites Dalmatae ("Dalmatian cavalry"). Little is known about these, but they were prominent in the 4th century, with several units listed in the Notitia Dignitatum.

Camel troops

A unit of dromedarii ("camel-mounted troops") is attested from the 2nd century, the ala I Ulpia dromedariorum milliaria in Syria.

Archers

A substantial number of auxiliary regiments (32, or about 1 in 12 in the 2nd century) were denoted sagittariorum, or archer-units (from sagittarii
Sagittarii
Sagittarii Sagitarii is the latin term for archers. The term sagittariorum in the title of an infantry or cavalry unit indicated a specialized archer regiment. Regular auxiliary units of foot and horse archers appeared in the Roman army during the early empire...

lit. "arrow-men", from sagitta = "arrow": It. saetta, Rom. sageata). These 32 units (of which 4 were double-strength) had a total official strength of 17,600 men. All three types of auxiliary regiment (ala, cohors and cohors equitata) could be denoted sagittariorum. Although these units evidently specialised in archery, it is uncertain from the available evidence whether all sagittariorum personnel were archers, or simply a higher proportion than in ordinary units. At the same time, ordinary regiments probably also possessed some archers, otherwise their capacity for independent operations would have been unduly constrained. Bas-reliefs appear to show personnel in ordinary units employing bows.

From about 218 BC onwards, the archers of the Roman army of the mid-Republic

Roman army of the mid-Republic

were virtually all mercenaries from the island of Crete

Crete

Crete is the largest and most populous of the Greek islands, the fifth largest island in the Mediterranean Sea, and one of the thirteen administrative regions of Greece. It forms a significant part of the economy and cultural heritage of Greece while retaining its own local cultural traits...

, which boasted a long specialist tradition. During the late Republic (88-30 BC) and the Augustan period, Crete was gradually eclipsed by men from other, much more populous, regions with strong archery traditions, newly subjugated by the Romans. These included Thrace

Thrace

Thrace is a historical and geographic area in southeast Europe. As a geographical concept, Thrace designates a region bounded by the Balkan Mountains on the north, Rhodope Mountains and the Aegean Sea on the south, and by the Black Sea and the Sea of Marmara on the east...

, Anatolia

Anatolia

Anatolia is a geographic and historical term denoting the westernmost protrusion of Asia, comprising the majority of the Republic of Turkey...

and above all, Syria

Syria

Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....

. Of the 32 sagittarii units attested in mid 2nd century, 13 have Syrian names, 7 Thracian, 5 from Anatolia, 1 from Crete and the remaining 6 of other or uncertain origin.

Three distinct types of archers are shown on Trajan's Column: (a) with scalar cuirass, conical steel helmet and cloak; (b) without armour, with cloth conical cap and long tunic; or (c) equipped in the same way as general auxiliary foot-soldiers (apart from carrying bows instead of javelins). The first type were probably Syrian or Anatolian units; the third type probably Thracian. The standard bow used by Roman auxilia was the recurved composite bow

Composite bow

A composite bow is a bow made from horn, wood, and sinew laminated together. The horn is on the belly, facing the archer, and sinew on the back of a wooden core. Sinew and horn will store more energy than wood for the same length of bow...

, a sophisticated, compact and powerful weapon.

Slingers

From about 218 BC onwards, the Republican army's slingers were exclusively mercenaries from the Balearic Islands

Balearic Islands

The Balearic Islands are an archipelago of Spain in the western Mediterranean Sea, near the eastern coast of the Iberian Peninsula.The four largest islands are: Majorca, Minorca, Ibiza and Formentera. The archipelago forms an autonomous community and a province of Spain with Palma as the capital...

, which had nurtured a strong indigenous tradition of slinging from prehistoric times. As a result, in classical Latin, Baleares (literally "inhabitants of the Balearic Islands") became an alternative word for "slingers" (funditores, from funda = "sling": It. fionda, Fr. fronde). Because of this, it is uncertain whether the most of the imperial army's slingers continued to be drawn from the Balearics themselves, or, like archers, derived mainly from other regions.

Independent slinger units are not attested in the epigraphic record of the Principate. However, slingers are portrayed on Trajan's Column. They are shown unarmoured, wearing a short tunic. They carry a cloth bag, slung in front, to hold their shot (glandes).

Scouts

Exploratores ("reconnaissance troops", from explorare = "to scout"): Examples include two numeri exploratorum attested in the 3rd century in Britain: Habitanco and Bremenio (both names of forts). Little is known about such units.

Irregular allied forces

Throughout the Principate period, there is evidence of ethnic units of barbari outside the normal auxilia organisation fighting alongside Roman troops. To an extent, these units were simply a continuation of the old client-king levies of the late Republic: ad hoc bodies of troops supplied by Rome's puppet petty-kings on the imperial borders for particular campaigns. Some clearly remained in Roman service beyond the campaigns, keeping their own native leadership, attire and equipment and structure. These units were known to the Romans as socii ("allies"), symmachiarii (from symmachoi, Greek for "allies") or foederati
Foederati
Foederatus is a Latin term whose definition and usage drifted in the time between the early Roman Republic and the end of the Western Roman Empire...

("treaty troops" from foedus, "treaty"). One estimate puts the number of foederati in the time of Trajan at ca. 11,000, divided into ca. 40 numeri (units) of ca. 300 men each. The purpose of employing foederati units was to use their specialist fighting skills. Many of these would have been troops of Numidian cavalry (see light cavalry above).

The foederati make their first official appearance on Trajan's Column, where they are portrayed in a standardised manner, with long hair and beards, barefoot, stripped to the waist, wearing long trousers held up by wide belts and wielding clubs. In reality several different tribes supported the Romans in the Dacian wars. Their attire and weapons would have varied widely. The Column stereotypes them with the appearance of a single tribe, probably the most outlandish-looking, to differentiate them clearly from the regular auxilia. Judging by the frequency of their appearance in the Column's battle scenes, the foederati were important contributors to the Roman operations in Dacia. Another example of foederati are the 5,500 captured Sarmatian cavalrymen sent by Emperor Marcus Aurelius (r. 161–180) to garrison a fort on Hadrian's Wall after their defeat in the Marcomannic Wars

Marcomannic Wars

Legions

As had been the case during the Republic, the legions of the Principate era recruited Roman Citizens exclusively. In the 1st and 2nd centuries, these represented a minority of the empire's inhabitants (about 10 - 20%). From the time of Augustus, legionary recruitment was largely voluntary. Republican-style conscription of citizens was only resorted to during emergencies which demanded exceptionally heavy recruitment, such as the Illyrian revolt (AD 6-9).

Once the borders of the empire stabilised in the mid-1st century, most legions were based in particular provinces long-term. The number of Italian-born recruits dwindled. According to one survey, ca. 65% were Italian-born in the early Julio-Claudian period (to AD 41), 49% in the period 42-68, 21% in the Flavian era (69-96) and around 8% under Hadrian. Italians thus represented ca. 4% of total army recruits under Hadrian, if one takes into account the auxilia, despite constituting ca. 12% of the empire's population, and well over 50% of its citizen-body, in 164. However, it should be borne in mind that many legionary recruits born outside Italy were residents of Roman colonies originally established to settle legionary veterans. As descendants of the latter, such recruits were, at least partially, of Italian blood; e.g. the emperor Hadrian, who was born in the Roman colony of Italica
Italica
The city of Italica was founded in 206 BC by the Roman general Publius Cornelius Scipio Africanus in order to settle Roman soldiers wounded in the Battle of Ilipa, where the Carthaginian army was defeated during the Second Punic War...

in Spain and both of whose parents were of mixed Italo-Iberian blood. However, the proportion of legionaries of Italian blood dropped still further as the progeny of auxiliary veterans, who were granted citizenship on discharge, became a major source of legionary recruits. It was probably to redress this shortfall that Marcus Aurelius, faced with a major war against the Marcomanni, raised two new legions in 165, II Italica
Legio II Italica
Legio secunda Italica , was a Roman legion levied by emperor Marcus Aurelius in 165 together with I Italica at a time when the Roman Empire was fighting both in Germania and in Parthia. There are still records of the II Italica in Noricum in the beginning of the 5th century...

and III Italica
Legio III Italica
Legio tertia Italica was a Roman legion levied by Marcus Aurelius around 165, for his campaign against the Marcomanni tribe. The cognomen Italica suggests that recruits were originally from Italy. The legion was still active in Raetia and other provinces in the early 5th century Legio tertia...

, apparently from Italian recruits (and presumably by conscription).

A major recruitment problem for the legions was that the host provinces often lacked a sufficiently large base of citizens to satisfy their recruiment needs. For example, Britannia

Britannia

Britannia is an ancient term for Great Britain, and also a female personification of the island. The name is Latin, and derives from the Greek form Prettanike or Brettaniai, which originally designated a collection of islands with individual names, including Albion or Great Britain. However, by the...

province, where Mattingly doubts that the 3 legions deployed could fill their vacancies from a citizen-body of only ca. 50,000 in AD 100 (less than 3% of about 2 million total inhabitants). This implies that the British legions must have drawn many recruits from elsewhere, especially from northern Gaul.

The frontier legions' recruitment problems have led some historians to suggest that the rule limiting legionary recruitment to citizens was largely ignored in practice. But the evidence is that the rule was strictly enforced e.g. the recorded case of 2 recruits who were sentenced to be flogged and then expelled from a legion when it was discovered that they had lied about their status. The only significant exception to the rule appears to have concerned the sons of legionaries. From the time of Augustus until the rule of Septimius Severus (197-211), serving legionaries were legally prohibited from marrying (presumably so as to discourage them from deserting if they were deployed far from heir families). However, with most legions deployed in the same bases long-term, legionaries often did develop stable relationships and bring up children. The latter, although of Roman blood, were illegitimate in Roman law

Roman law

Roman law is the legal system of ancient Rome, and the legal developments which occurred before the 7th century AD — when the Roman–Byzantine state adopted Greek as the language of government. The development of Roman law comprises more than a thousand years of jurisprudence — from the Twelve...

and thus could not inherit their fathers' citizenship. Nevertheless, it appears that the sons of serving legionaries were routinely recruited, perhaps through the device of granting them citizenship when they enlisted.

Auxilia

In the 1st century, the vast majority of auxiliary common soldiers were recruited from the Roman peregrini (second-class citizen

Second-class citizen

Second-class citizen is an informal term used to describe a person who is systematically discriminated against within a state or other political jurisdiction, despite their nominal status as a citizen or legal resident there...

s). In the Julio-Claudian era (to AD 68), conscription

Conscription

Conscription is the compulsory enlistment of people in some sort of national service, most often military service. Conscription dates back to antiquity and continues in some countries to the present day under various names...

of peregrini seems to have been practiced, probably in the form of a fixed proportion of men reaching military age in each tribe being drafted, alongside voluntary recruitment. From the Flavian era onwards, it appears that the auxilia were, like the legions, a largely volunteer force, with conscription resorted to only in times of extreme manpower demands e.g. during Trajan's Dacian Wars (101-6). Although recruits as young as 14 are recorded, the majority of recruits (66%) were from the 18–23 age group.

When it was first raised, an auxiliary regiment would have been recruited from the native tribe or people whose name it bore. In the early Julio-Claudian period, it seems that efforts were made to preserve the ethnic integrity of units, even when the regiment was posted in a faraway province, but in the later part of the period, recruitment in the region where the regiment was posted increased and became predominant from the Flavian era onwards. The regiment would thus lose its original ethnic identity. The unit's name would thus become a mere curiosity devoid of meaning, although some of its members might inherit foreign names from their veteran ancestors. This view has to be qualified, however, as evidence from military diplomas and other inscriptions shows that some units continued to recruit in their original home areas e.g. Batavi units stationed in Britain, where several other units had an international membership. It also appears that the Danubian provinces (Raetia, Pannonia, Moesia, Dacia) remained key recruiting grounds for units stationed all over the empire.

About 50 auxiliary regiments founded by Augustus were, exceptionally, recruited from Roman citizens. This was due to the emergency manpower requirements of the Illyrian revolt (AD 6-9), which was described by the Roman historian Suetonius

Suetonius

Gaius Suetonius Tranquillus, commonly known as Suetonius , was a Roman historian belonging to the equestrian order in the early Imperial era....

as the most difficult conflict Rome had faced since the Punic Wars

Punic Wars

The Punic Wars were a series of three wars fought between Rome and Carthage from 264 B.C.E. to 146 B.C.E. At the time, they were probably the largest wars that had ever taken place...

. Although the Republican minimum property requirement for admission to the legions had long since been abandoned, citizens who were vagrants, convicted criminals, undischarged debtors, or freed slaves (Roman law accorded citizenship to the freed slaves of Roman citizens) were still excluded. Desperate for recruits, Augustus had already resorted to the compulsory purchase and emancipation of thousands of slaves for the first time since the aftermath of the Battle of Cannae

Battle of Cannae

The Battle of Cannae was a major battle of the Second Punic War, which took place on August 2, 216 BC near the town of Cannae in Apulia in southeast Italy. The army of Carthage under Hannibal decisively defeated a numerically superior army of the Roman Republic under command of the consuls Lucius...

two centuries earlier. But the emperor found the idea of admitting such men to the legions unpalatable. So he formed separate auxiliary regiments from them. These units were accorded the title civium Romanorum ("of Roman citizens"), or c.R. for short. After the Illyrian revolt, these cohorts remained in being and recruited peregrini like other auxiliary units, but retained their prestigious c.R. title. Subsequently, many other auxiliary regiments were awarded the c.R. title for exceptional merit, an award that conferred citizenship on all their currently serving members.

Apart from the citizen-regiments raised by Augustus, Roman citizens were regularly recruited to the auxilia. Most likely, the majority of citizen-recruits to auxiliary regiments were the sons of auxiliary veterans who were enfranchised on their fathers' discharge. Many such men may have preferred to join their fathers' old regiments, which were a kind of extended family to them, rather than join a much larger, unfamiliar legion. Legionaries frequently transferred to the auxilia (mostly promoted to a higher rank). The incidence of citizens in the auxilia would thus have grown steadily over time until, after the grant of citizenship to all peregrini in 212, auxiliary regiments became predominantly, if not exclusively, citizen units.

It is less clear-cut whether the regular auxilia recruited barbari (barbarians, as the Romans called people living outside the empire's borders). Although there is little evidence of it before the 3rd century, the consensus is that the auxilia recruited barbarians throughout their history. In the 3rd century, a few auxilia units of clearly barbarian origin start to appear in the record e.g. Ala I Sarmatarum, cuneus Frisiorum and numerus Hnaufridi in Britain.

Ranks, role and pay

A legion's ranks, role and pay, with auxiliary and modern equivalents, may be summarised as follows:

LEGIONS: Ranks, Role and Pay (ca. AD 100)
! Pay-scale
*(X basic) !!* Legionary rank
(ascending order) !! Number
in legion !! Role !! Auxilia
equivalent:
*cohors* (*ala*) !! Social
rank !! Approx. modern
rank-equivalent (U.K.)
1	pedes	5,120	infantryman	pedes (eques)	commoner	private Private (rank) A Private is a soldier of the lowest military rank .In modern military parlance, 'Private' is shortened to 'Pte' in the United Kingdom and other Commonwealth countries and to 'Pvt.' in the United States.Notably both Sir Fitzroy MacLean and Enoch Powell are examples of, rare, rapid career...
1.5	cornicen Cornicen A cornicen was a junior officer in the Roman Army. The cornicen's job was to signal salutes to officers and sound orders to the legions. The cornicines played the cornu . Cornicines always marched at the head of the centuries, with the tesserary and the signifer... tesserarius Tesserarius A tesserarius , was a watch commander in the Roman army. They organized and had command over the nightly guard assigned to keep watch over the fort when in garrison or on campaign and were responsible for getting the watchwords from the commander and seeing that it was kept safe. There was one...	59 59	horn-blower officer of the watch	cornicen tesserarius (sesquiplicarius)	commoners	corporal Corporal Corporal is a rank in use in some form by most militaries and by some police forces or other uniformed organizations. It is usually equivalent to NATO Rank Code OR-4....
2	optio Optio An optio , sometimes anglicized option , was a soldier in the Roman army who held a position similar to that of an executive officer in modern armies... signifer Signifer A signifer was a standard bearer of the Roman legions. He carried a signum for a cohort or century. Each century had a signifer and within each cohort the first century's signifer would be the senior.... imaginifer Imaginifer The imaginifer was one of the signiferi in a legion in the times of the Roman Empire, who carried the imago - the image - of the emperor. The imaginifer was added to the ranks of the legions when the Imperial Cult was first established during the reign of Augustus. The imago was a three... aquilifer Aquilifer An aquilifer was a senior signifer bearing the eagle standard of a Roman legion. The name derives from the type of standard, aquila meaning "eagle", which was the universal type used since 104 BC. Before that time, the wolf, boar, bull and horse were also used...	59 59 1 1	centurion's deputy centuria standard-bearer bearer of emperor's image legion standard-bearer	optio (duplicarius) signifer vexillarius - - - - (curator)	commoners	sergeant Sergeant Sergeant is a rank used in some form by most militaries, police forces, and other uniformed organizations around the world. Its origins are the Latin serviens, "one who serves", through the French term Sergent....
16	centurio Centurion A centurion was a professional officer of the Roman army .Centurion may also refer to:-Military:* Centurion tank, British battle tank* HMS Centurion, name of several ships and a shore base of the British Royal Navy...	45	centurion	centurio (decurio Decurio Decurio was an official title in Ancient Rome, used in various connections:# A member of the senatorial order in the Italian towns under the administration of Rome, and later in provincial towns organized on the Italian model . The number of decuriones varied in different towns, but was usually 100... )	commoner	company sergeant-major
n.a.	centurio primi ordinis	13 (9 pilus prior + 4 1st Cohort)	senior centurion	centurio princeps (decurio princeps)	commoner	regimental sergeant-major
n.a.	centurio primus pilus⁽¹⁾	1	chief centurion	none	commoner⁽¹⁾
50	tribunus militum angusticlavius	5	legion staff-officer	praefectus auxilii (regimental commander)	knight	colonel Colonel Colonel , abbreviated Col or COL, is a military rank of a senior commissioned officer. It or a corresponding rank exists in most armies and in many air forces; the naval equivalent rank is generally "Captain". It is also used in some police forces and other paramilitary rank structures...
n.a.	praefectus castrorum Praefectus Castrorum The praefectus castrorum was, in the Roman army of the early Empire, the third-most senior commander of the Roman legion, after the legate and the senior military tribune . His responsibility was looking after equipment and building works but could command the legion when his seniors were absent...	1	legion quartermaster (executive officer)	none	knight
n.a.	tribunus militum laticlavius	1	legion deputy commander	none	senatorial (senator's son)
70	legatus legionis Legatus A legatus was a general in the Roman army, equivalent to a modern general officer. Being of senatorial rank, his immediate superior was the dux, and he outranked all military tribunes...	1	legion commander	none	senator	general General A general officer is an officer of high military rank, usually in the army, and in some nations, the air force. The term is widely used by many nations of the world, and when a country uses a different term, there is an equivalent title given....

Notes: (1) Elevated by emperor to equestrian rank on completion of single-year term of office

Explanation of modern rank comparisons: It is difficult to make exact comparisons with the ranks of an army from the pre-industrial age where noble birth was the pre-requisite for senior positions and such comparisons should be treated with caution. Nevertheless, some approximate parallels can be found. The ones presented here are drawn from Grant's translation of the Annales
Annals (Tacitus)
The Annals by Tacitus is a history of the reigns of the four Roman Emperors succeeding Caesar Augustus. The surviving parts of the Annals extensively cover most of the reigns of Tiberius and Nero. The title Annals was probably not given by Tacitus, but derives from the fact that he treated this...

by Tacitus

Tacitus

.

As they mostly rose from the ranks, centurions are compared to modern sergeants-major, the most senior officers without a commission. An ordinary centurion was in command of a centuria of 80 men, equivalent to a company

Company (military unit)

in a modern army, and is thus comparable to a company sergeant-major. Senior centurions, known as primi ordinis ("of the first order"), consisted of the 5 commanders of the double-strength centuriae of the First Cohort (160 men each); and the 9 pilus prior centurions (commanders of the 1st centuria of each cohort), who in the field presumably led their whole cohort of 480 men, equivalent to a modern battalion

Battalion

A battalion is a military unit of around 300–1,200 soldiers usually consisting of between two and seven companies and typically commanded by either a Lieutenant Colonel or a Colonel...

. A senior centurion is thus likened to a regimental sergeant-major, the most senior non-commissioned officer in a battalion. The primus pilus, the chief centurion of the legion, has no clear parallel.

From the centurionate, the rank-structure jumps to the military tribunes, aristocrats who were directly appointed senior officers and thus comparable to modern commissioned officers. Since in the field they could command one or more cohorts (and their equivalent in the auxilia, a praefectus commanded a cohort-sized regiment), these officers are comparable to modern colonel

Colonel

Colonel , abbreviated Col or COL, is a military rank of a senior commissioned officer. It or a corresponding rank exists in most armies and in many air forces; the naval equivalent rank is generally "Captain". It is also used in some police forces and other paramilitary rank structures...

s, who normally command battalions or regiments in a modern army. Finally, the legatus legionis was in command of the whole legion (over 5,000 men, equivalent to a modern brigade

Brigade

), plus roughly the same number of auxiliaries in attached regiments, bringing the total to ca. 10,000 men, equivalent to a modern division

Division (military)

A division is a large military unit or formation usually consisting of between 10,000 and 20,000 soldiers. In most armies, a division is composed of several regiments or brigades, and in turn several divisions typically make up a corps...

. Thus a legatus is comparable to a modern general officer. The legions thus lacked any equivalent to modern junior commissioned officers (lieutenant

Lieutenant

A lieutenant is a junior commissioned officer in many nations' armed forces. Typically, the rank of lieutenant in naval usage, while still a junior officer rank, is senior to the army rank...

to major

Major

Major is a rank of commissioned officer, with corresponding ranks existing in almost every military in the world.When used unhyphenated, in conjunction with no other indicator of rank, the term refers to the rank just senior to that of an Army captain and just below the rank of lieutenant colonel. ...

). This is because the Romans saw no need to complement their centurions, who were considered fully capable of field commands, with commissioned officers. As a consequence, a chief centurion promoted to praefectus castrorum would leap from sergeant-major to the rank of colonel in one bound.

Rankers (caligati)

At the bottom end of the rank pyramid, rankers were known as caligati (lit: "sandalled men" from the caligae or hob-nailed sandals worn by soldiers), or simply as milites ("soldiers"). Depending on the type of regiment they belonged to, they held the official ranks of pedes (foot soldier in a legion or auxiliary cohors), eques (cavalryman in legionary cavalry or an auxiliary cohors equitata) and eques alaris (ala cavalryman). A new recruit under training was known as a tiro, and received half-pay.

Soldiers' working lives were arduous. As well as facing the hardships of military discipline and training, and the dangers of military operations, soldiers fulfilled a large number of other functions, such as construction workers, policemen, and tax collectors (see below, Everyday life). It has been estimated from the available data that only an average of ca. 50% of recruits survived their 25-year term of service. This mortality rate was well in excess of the contemporary demographic norm for the 18-23 age-group. An indication of the rigours of military service in the imperial army may be seen in the complaints aired by rebellious legionaries during the great mutinies that broke out in the Rhine and Danube legions on the death of Augustus in AD 14.

"Old men, mutilated by wounds are serving their 30th or 40th year. And even after your official discharge, your service is not finished. For you stay on with the colours as a reserve, still under canvas - the same drudgery under another name! And if you manage to survive all these hazards, even then you are dragged off to a remote country and settled in some waterlogged swamp or untilled mountainside. Truly the army is a harsh, unrewarding profession! Body and soul are reckoned at two and a half sesterces a day - and with this you have to find clothes, weapons, tents and bribes for brutal centurions if you want to avoid chores. Heaven knows, lashes and wounds are always with us! So are hard winters and hardworking summers..."

"The soldiers' reply was to tear off their clothes and point to the scars left by their wounds and floggings. There was a confused roar about their wretched pay, the high cost of exemptions from duty, and the hardness of the work. Specific reference was made to earthworks, excavations, foraging, collecting timber and firewood..."

The gross and net pay of legionaries and auxiliaries may be summarised as follows:

REMUNERATION OF ROMAN COMMON FOOT SOLDIERS (about AD 70)
Remuneration item	legionary pedes: amount (denarii) (annualised)	XXX	auxiliary pedes amount (denarii) (annualised)
*Stipendium* (gross salary)	225		188

Less: Food deduction	60		60
Less: Equipment etc. deductions	50		50

Net disposable pay	115		78

Plus: *Donativa* (bonuses) (average: 75 denarii every 3 years)	25		none proven

Total disposable income	140		78

*Praemia* (discharge bonus: 3,000 denarii)	120		none proven

Basic legionary pay was set at 225 denarii per annum under Augustus. Until at least AD 100, auxiliary soldiers were apparently paid less than their legionary counterparts. In the early Julio-Claudian period, it has been suggested that an auxiliary foot-soldier was paid only a third the rate of a legionary (although an eques alaris was paid two-thirds). By AD 100, the differential had narrowed dramatically. An auxiliary pedes was paid 20% less than his legionary counterpart at the time of Domitian

Domitian

(81-97) (but an eques cohortalis the same and an eques alaris 20% more). Soldiers' pay was increased by 33% denarii under Domitian (r.81-96). Septimius Severus (r. 197-211) increased the rate by a further 25%, and then his successor Caracalla (r. 211-8) by 50% again. But in reality, these pay rises only more-or-less covered price inflation over this period, which is estimated at ca. 170% by Duncan-Jones. Since the debasement of the central silver coinage, the denarius, roughly reflected general inflation, it can be used as a rough guide to the real value of military pay:

REAL TREND OF LEGIONARY PAY (AD 14 - 215)
! Emperor !! Nominal pay
of legionary
(*denarii*) !! No. of *denarii*
minted from 1 lb. silver !! Real pay
of legionary
(in constant AD 14 *denarii*)
Augustus (to AD 14)	225	85	225
Vespasian (70-81)	225	103	186
Domitian (81-96)	300	101	252
Hadrian (117-38)	300	105	243
S. Severus (197-211)	400	156	218
Caracalla (211-8)	600	192	265

Furthermore, a soldier's gross salary was subject to deductions for food and equipment. The latter included weapons, tents, clothing, boots and hay (probably for the company mules). These deductions would leave the 1st-century legionary with a modest disposable income of ca. 115 denarii, and an auxiliary 78 denarii.

A legionary's daily pay-rate of 2.5 sesterces was only marginally greater than a common day-labourer in Rome could expect in this period (typically 2 sesterces per day). Such modest remuneration for a tough service raises the question of how the imperial army succeeding in raising sufficient volunteers with only the occasional recourse to conscription. The reason is that the comparison with a Rome day-labourer is misleading. The vast majority of the army's recruits were drawn from provincial peasant families living on subsistence farming i.e. farmers who after paying rent, taxes and other costs were left with only enough food to survive: the situation of ca. 80% of the Empire's population. To such persons, any disposable income would appear attractive, and the physical rigours of army service no worse than back-breaking drudgery in the fields at home. In any case, where a peasant family had more children than its plot of land could support, enlistment of one or more sons in the military would have been a matter of necessity, rather than choice.

In addition, soldiers enjoyed significant advantages over day-labourers. They had job security for life (assuming they were not dishonourably discharged). Legionaries could count on irregular but substantial cash bonuses (donativa), paid on the accession of a new emperor and on other special occasions; and, on completion of service, a substantial discharge-bonus (praemia) equivalent to 13 years' gross pay, which would enable him to buy a large plot of land. Auxiliaries were exempt from the annual poll-tax payable by all their fellow-peregrini and were rewarded on discharge with Roman citizenship for themselves and their heirs. Duncan-Jones argues that, at least from the time of Hadrian, auxiliaries also received donativa and praemia. Finally, a ranker had a 1 in 20 chance of increasing his pay by 50-100% by gaining promotion to the rank of principalis or junior officer. Out of 480 men, a typical cohort would contain 24 junior officers (other than specialists).

The great mutinies of AD 14, which were about pay and conditions - as distinct from later revolts in support of a contender for the imperial throne - were never repeated. The reason they occurred at all was probably because, at the time, many legionaries were still conscripts (mostly enlisted during the Illyrian revolt crisis of AD 6-9) and the majority still Italians. This made them far less tolerant of the hardships of military life than provincial volunteers. Italians were by this stage used to a higher standard of living than their provincial subjects, largely due to a massive effective subsidy by the latter: Italians had long been exempt from direct taxation on land and heads and, at the same time, rents from the vast imperial and private Roman-owned estates carved out by conquest in the provinces largely flowed to Italy. Thus, a central demand of the 14 CE mutineers was that legionary pay be increased from 2.5 to 4 sesterces (1 denarius) per day. This was conceded by Tiberius in order to pacify the mutiny, but soon revoked as unaffordable, and pay remained at roughly the same real level into the 3rd century.

Rankers with specialist skills were classed as milites immunes ("exempt soldiers"), meaning that they were exempt from the normal duties of their fellow-soldiers so that they could practice their trade. A legion would contain over 600 immunes. Over 100 specialist jobs are attested, including the all-important blacksmith

Blacksmith

A blacksmith is a person who creates objects from wrought iron or steel by forging the metal; that is, by using tools to hammer, bend, and cut...

s (fabri), among whom the scutarii ("shield-men"), probably smiths that specialised in weapons manufacture or repair, and other craftsmen who worked in the fabrica; carpentarii ("wagon-makers/repairers", or, generally, "carpenters"); capsarii (wound-dressers) and seplasiarii ("ointment-men"), medical orderlies who worked in the valetudinarium (hospital in a legionary fortress) or hospitium (auxiliary fort hospital); balniator (bath attendant); and cervesarius (beer-brewer). It is uncertain, however, whether the latter two jobs were held by milites immunes or by civilians working for the unit on contract. Immunes were on the same pay-scale as other rankers.

Legions

Below centurion rank, junior officers in the centuria were known as principales. Principales, together with some specialists, were classified in two pay-scales: sesquiplicarii ("one-and-a-half-pay soldiers") and duplicarii ("double-pay soldiers"). These ranks probably most closely resembled the modern ranks of corporal

Corporal

Corporal is a rank in use in some form by most militaries and by some police forces or other uniformed organizations. It is usually equivalent to NATO Rank Code OR-4....

and sergeant

Sergeant

Sergeant is a rank used in some form by most militaries, police forces, and other uniformed organizations around the world. Its origins are the Latin serviens, "one who serves", through the French term Sergent....

respectively. A higher rank of triplicarius ("triple-pay soldier") is attested very rarely in the 1st century and this pay-scale was probably short-lived. Sesquiplicarii included the cornicen
Cornicen
A cornicen was a junior officer in the Roman Army. The cornicen's job was to signal salutes to officers and sound orders to the legions. The cornicines played the cornu . Cornicines always marched at the head of the centuries, with the tesserary and the signifer...

(horn-blower), who blew the cornu
Cornu (horn)
A cornu or cornum was a type of brass instrument similar to the buccina used by the Roman army of antiquity mainly for communicating orders to troops in battle. It is a Latin word literally meaning horn. The instrument was about long and took the form of a letter 'G'...

, a long, three-piece circular horn. Above him was the tesserarius
Tesserarius
A tesserarius , was a watch commander in the Roman army. They organized and had command over the nightly guard assigned to keep watch over the fort when in garrison or on campaign and were responsible for getting the watchwords from the commander and seeing that it was kept safe. There was one...

(literally "tablet-holder", from tessera = "wax tablet", on which the daily password was inscribed), who was the officer of the watch. Duplicarii, in ascending order of rank, were the optio
Optio
An optio , sometimes anglicized option , was a soldier in the Roman army who held a position similar to that of an executive officer in modern armies...

, or centurion's deputy, who was appointed by his centurion and would expect to succeed him when the latter was promoted. While a centurion led his unit from the front in battle, his optio would bring up the rear. Responsible for preventing rankers from leaving the line, the optio was equipped with a long, silver-tipped stave which was used to push the rear ranks forward. Ranking just below centurion was the signifer
Signifer
A signifer was a standard bearer of the Roman legions. He carried a signum for a cohort or century. Each century had a signifer and within each cohort the first century's signifer would be the senior....

(standard-bearer), who bore the centuria signum. In the field, the signifer wore the skin of a lion's head over his own. At the legionary level, the vexillarius had charge of the commander's vexillum
Vexillum
The vexillum was a flag-like object used in the Classical Era of the Roman Empire. The word is itself a diminutive for the Latin word, velum, sail, which confirms the historical evidence that vexilla were literally "little sails" i.e. flag-like standards...

, or banner, and accompanied the legatus in the field. The aquilifer
Aquilifer
An aquilifer was a senior signifer bearing the eagle standard of a Roman legion. The name derives from the type of standard, aquila meaning "eagle", which was the universal type used since 104 BC. Before that time, the wolf, boar, bull and horse were also used...

bore the legion's aquila standard, and accompanied the chief centurion, as did the legion's imaginifer, who bore a standard with the emperor's image. All these standard-bearers were duplicarii.

Auxilia

An auxiliary regiment's ranks appear broadly the same as in a legionary centuria. These were, in ascending order: tesserarius, optio, signifer (standard-bearer for the centuria). However, all auxiliary regiments also contained a custos armorum ("keeper of the armoury"), on pay-and-a-half. In addition, there was a vexillarius, who bore the cohort's vexillum, on double-pay. In the alae, ranks were somewhat differently named. The equivalent of tesserarius was known simply as a sesquiplicarius and of optio as a duplicarius. In addition, there was a rank of curator on double-pay just below decurion, who apparently was in charge of horses and caparison.

Legions

The great majority of rankers never advanced beyond principalis. The few who did became centurion

Centurion

A centurion was a professional officer of the Roman army .Centurion may also refer to:-Military:* Centurion tank, British battle tank* HMS Centurion, name of several ships and a shore base of the British Royal Navy...

s, a rank that they would normally attain after 13–20 years of service. Promotion to the centurionate, known to the Romans simply as the ordo, or "rank", was normally in the hands of the legatus legionis. However, the latter occasionally followed the Republican tradition and allowed the men of a centuria to elect their own centurion. Although most centurions rose from the ranks, it was possible for a young man to be directly commissioned: these were mostly the sons of active or retired centurions.

Centurions were arguably the most important group of officers in the army, as they led the legions' tactical sub-units (cohorts and centuriae) in the field. In consequence, on becoming a centurion, a soldier's pay and prestige would undergo a quantum-leap. Centurions were paid far more than their men. The available evidence is scant, but suggests that, in the 2nd century, an ordinary centurion was paid 16 times the pay of a ranker. If so, the differential had widened dramatically since the days of the Punic Wars, when a centurion was paid just double the rate of a ranker i.e. was a duplicarius in imperial terms. By the time of Caesar, the standing of centurions had greatly increased: in 51 BC, after an especially tough campaign during the Gallic War, Caesar promised his troops a bonus of 50 denarii per man, and 500 each to the centurions, indicating that a differential of 10 times was commonplace even in the late Republic.

Each legion contained 60 (later 59) centurions, ranked in an elaborate hierarchy. Each cohort was ranked in seniority, the 1st Cohort (whose centuriae, after about AD 80, were double-strength) being the highest. Within each cohort, each centuria, and thus its commanding centurion, was similarly ranked. Within this hierarchy, three broad ranks can be discerned: ordinary centurions, senior centurions (primi ordinis or "first rank") and the legion's chief centurion (primus pilus). Senior centurions included those in command of the 5 centuriae in the 1st Cohort and the pilus prior ("front-spear") centurions of the other 9 cohorts.

All centurions, including the primus pilus, were expected to lead their units from the front, on foot like their men, and were invariably in the thick of any combat melee. As a consequence, their casualty rates in battle were often very heavy. An example from Caesar's De Bello Gallico, during a battle against the Belgic

Belgae

The Belgae were a group of tribes living in northern Gaul, on the west bank of the Rhine, in the 3rd century BC, and later also in Britain, and possibly even Ireland...

tribes of northern Gaul (57 BC): " After addressing the 10th legion, Caesar had gone to the right wing, where he found the troops in difficulties... All the centurions of the 4th cohort [of the 12th legion] were dead, and the standard lost; nearly all the centurions of the rest of the cohorts were either killed or wounded, including the chief centurion, P. Sextius Baculus, a very brave man, who was so disabled by serious wounds that he could no longer stand on his feet." Or again, in a later battle against Vercingetorix

Vercingetorix

Vercingetorix was the chieftain of the Arverni tribe, who united the Gauls in an ultimately unsuccessful revolt against Roman forces during the last phase of Julius Caesar's Gallic Wars....

at Gergovia (52 BC): "Attacked from all sides, our men held their ground until they had lost 46 centurions..." In battle, centurions were also responsible for the security of their unit's standard, whose bearer, the signifer, stayed close to his centurion on the battlefield. The chief centurion was accompanied by the aquilifer and had the even weightier responsibility of protecting the legion's aquila
Aquila (Roman)
The Aquila was the eagle standard of a Roman legion, carried by a special grade legionary known as an Aquilifer. One eagle standard was carried by each legion.-History:...

(eagle-standard).

Centurions were also responsible for discipline in their units, symbolised by the vitis or vine-stick which they carried as a badge of their rank. But the stick was by no means purely symbolic and was frequently used to beat recalcitrant rankers. Tacitus relates that one centurion in the army in Pannonia gained the nickname Da mihi alteram! ("Give-me-another!") for his propensity to break his stick over his men's backs and then shout at his optio to bring him a new one. Centurions often earnt the hatred of their men, as shown during the great mutinies which broke out on the Rhine-Danube borders on the death of Augustus. One legion's centurions were each given 60 lashes of the flail by the mutineers, to represent the brigade's total number of centurions, and were then thrown into the Rhine to drown.

Outside the military sphere, centurions played performed a wide range of administrative duties, which was necessary in the absence of an adequate bureaucracy to support provincial governors. A centurion might serve as a regionarius, or district-supervisor, on behalf of the provincial governor. They were also relatively wealthy individuals, due to their high salaries. In retirement, they often held high civic positions in the councils of Roman coloniae (veterans' colonies).

However, in social rank, the vast majority of centurions were commoners. In the class-conscious system of the Romans, this rendered even senior centurions far inferior in status to any of its tribuni militum (who were all of equestrian rank), and ineligible to formally command any unit larger than a centuria. This is probably the reason why a cohort did not have a formal commander, although many historians believe that a cohort in the field was under the de facto command of its leading centurion, the pilus prior, the commander of the cohort's 1st centuria. The only escape-route for centurions from this "class-trap" was to reach the highest grade of primus pilus. On completing his single-year term of office, the chief centurion of each legion (i.e. some 30 individuals each year) was elevated to equestrian rank by the emperor.

At this point, the whole range of command positions reserved for knights would be attainable. Normally, a former primus pilus (known as a primipilaris) would be promoted to praefectus castrorum (quartermaster and third officer) of a legion or to tribune of a Praetorian cohort in Rome. However, primipilares rarely progressed beyond this level because of their age, unless they were the minority who were directly commissioned as young men. It would typically take a ranker 13–20 years just to reach centurion-rank and probably the same again to reach primus pilus. Most primipilares would thus be in their 50's when elevated to the Order of Knights, whereas hereditary knights would be appointed to military tribunates of a legion at around 30. Thus the higher posts reserved for knights, such as the governorates of equestrian provinces, command of the fleets or of the Praetorian Guard were rarely held by former centurions.

Auxilia

Auxiliary cohorts were also divided into centuriae, ranked in order of seniority. The centurion commanding the 1st centuria was known as the centurio princeps ("leading centurion") and was the 2nd-in-command of the cohort after the praefectus. In the cavalry, the equivalent rank was the decurio (decurion

Decurion (military)

A decurion was a Roman cavalry officer in command of a squadron of cavalrymen in the Roman army.- Republican army :...

), in command of a turma (squadron) of 30 troopers. Again, the decurion of the 1st turma was designated the decurio princeps.

Most of the surviving evidence concerns legionary centurions and it is uncertain whether their auxiliary counterparts shared their high status and non-military role. It appears that many auxiliary centuriones and decuriones were members of native provincial aristocracies who were directly commissioned. Auxiliary centurions risen from the ranks were thus probably less predominant than in the legions. Those rising from the ranks could be promotions from the legions as well as from the regiment's own ranks. In the Julio-Claudian period, auxiliary centurions and decurions were a roughly equal split between citizens and peregrini, though later citizens became predominant due to the spread of citizenship among military families. There is little evidence about the pay-scales of auxiliary centurions and decurions, but these are also believed to have amounted to several times that of their men.

Legions

5 of the legion's 6 military tribunes were known as angusticlavii ("narrow-banded", from the stripes a Roman knight was entitled to wear on his tunica, which was narrower than a senator's). They differed from their senatorial colleague, the laticlavius ("broad-banded"), in age, rank and experience. Before embarking on their military service (tres militiae), their normal cursus honorum required them to perform the full range of administrative and religious posts in the council of their home city. Minimum-age limits for such posts implied that they would be at least 30 before starting the tres militiae. By the time they became tribune of a legion, they would already have led an auxiliary cohort for 3 or 4 years, giving them substantial command experience. They were responsible for the legion's administration, for which they were provided with a personal staff of clerks and principales.

Tribunes' military role was apparently kept ill-defined and flexible, so as to provide the legion commander with a small group of senior officers to carry out special tasks. Tribunes could be asked to command detachments of one or more cohorts; command specialist units, such as a flotilla; lead special operations; supervise fortification projects or the collection of supplies. In a pitched battle scenario, the available evidence does not permit a clear picture of a tribune's role. For example, Caesar relates (57 BC): "Noticing that the 7th legion, which was nearby, was also under heavy pressure, Caesar ordered the military tribunes to gradually join together the two legions [the 7th and the 12th] and form a square formation, so that they could advance against the enemy in any direction." Or again (52 BC): "Caesar ordered the trumpeters to sound the retreat and the 10th legion, which was with him, immediately halted their advance. But the other legions did not hear the signal, as they were separated by a wide depression, although the legates and military tribunes did their best to hold them back, in accordance with Caesar's orders." This evidence is consistent with two possible battle-roles for tribunes. A tribune may have played a formal role in command of a sector of the legion's battle-line, perhaps in command of a pair of cohorts (so that the 5 tribunes would cover all 10 of the legion's cohorts). Alternatively, tribunes may have accompanied the legatus around the field, ready to convey his orders to particular senior centurions, or to assume command of a particular sector of the line at the behest of the legatus. In either case, as Roman knights, tribunes would move around the battle-field on horseback, not on foot like the centurions, and they would generally remain outside the fray, in order to maintain a strategic overview of the field.

There is no evidence regarding the pay of military tribunes. But since they ranked on a level with the commanders of auxiliary regiments, who were paid ca. 50 times more than rankers, it is safe to assume that tribunes were paid a similar multiple of legionary's pay. Tribunes' pay would in any case have fallen somewhere between the 16-multiple of centurions and the 70-multiple of legati.

The legion's third officer was the praefectus castrorum, a post mostly filled by former chief centurions. These would typically be in their 50's, having earnt their equestrian status by a lifetime of experience at the sharp end of legionary activity. In the absence of the legatus, they would normally deputise for them, under the nominal command of the laticlavius. From the time of Gallienus, these officers were routinely placed in command of their legion. The role of the praefectus was primarily that of quartermaster, in charge of the legion's camps and supplies, but also extended to advising the legatus on all manner of military operations.

The legate's nominal second-in-command was the single military tribune of senatorial rank attached to the legion, the laticlavius (literally: "broad-banded", referring to the wide stripe men of senatorial rank wore on their tunica). Typically the son of a senator (sometimes the legate's own son), and aged in his early twenties, he was performing his military service before seeking election as quaestor
Quaestor
A Quaestor was a type of public official in the "Cursus honorum" system who supervised financial affairs. In the Roman Republic a quaestor was an elected official whereas, with the autocratic government of the Roman Empire, quaestors were simply appointed....

and thereby gaining a seat in the Senate (for which the minimum age was 25 years). His lack of military experience did not prevent him leading important combat missions. In the Roman social system, his high birth would have commanded the automatic respect of even the most experienced commoner.

The commander of an imperial legion was known as the legatus legionis. He was typically a senator of praetorian rank i.e. he had held the post of praetor

Praetor

, implying that he would normally be in his mid-30's. His military experience would be limited to that gained as serving in his early twenties as tribunus laticlavius. As a consequence, he would rely heavily on the advice of his enormously experienced praefectus castrorum, who was his de facto executive officer, despite being outranked by the laticlavius. The evidence suggests that a legatus would be paid ca. 70 times a ranker's salary.

Auxilia

In the early Julio-Claudian period, the commanders of the auxiliary units (praefecti auxiliorum) were often senior centurions and so ranked below the legionary tribunes. The position changed under Claudius, who restricted command of auxiliary regiments to men of equestrian rank. Furthermore, an equestrian military cursus honorum became established, known as the tres militiae ("three commands"), each held for 3–4 years: command of an auxiliary cohort, followed by military tribune of a legion, followed by command of an ala. These reforms had the effect of elevating praefecti to the same rank as legionary tribunes. Under Hardian, a fourth militia, command of a double-strength ala milliaria was established for especially proficient officers.

It appears that in the 2nd century, the majority of auxiliary prefects were still of Italian origin. In contrast, the evidence for the 3rd century is that Italians provided less than a third of prefects.

The pay of a praefectus of an auxiliary regiment in the early 2nd century has been estimated at over 50 times that of a miles (common soldier). (This compares to a full colonel

Colonel

in the British Army, who is currently paid about 5 times a private's salary). The reason for the huge gap between the top and the bottom of the pyramid is that Roman society was far more hierarchical than a modern one. A praefectus was not just a senior officer. He was also a Roman citizen (which most of his men were not) and, as a member of the equestrian order, an aristocrat. The social gulf between the praefectus and a peregrinus soldier was thus immense, and the pay differential reflected that fact.

Army medical services

The Roman army had a strong interest in looking after the health of its effectives and developed a sophisticated medical service, based on the best medical knowledge and practice of the ancient world (i.e. Greek medicine). The Roman army's medics were highly skilled and possessed enormous practical experience. Although their knowledge was entirely empirical, not analytical, their practices were rigorously tried-and-tested on the battlefield and thus more effective than those available to most armies before the 19th century. (Roman army medics were, for example, far more competent than the "quacks

Quackery

Quackery is a derogatory term used to describe the promotion of unproven or fraudulent medical practices. Random House Dictionary describes a "quack" as a "fraudulent or ignorant pretender to medical skill" or "a person who pretends, professionally or publicly, to have skill, knowledge, or...

" of the 17th and 18th centuries with their lethal practices such as bleeding

Bloodletting

Bloodletting is the withdrawal of often little quantities of blood from a patient to cure or prevent illness and disease. Bloodletting was based on an ancient system of medicine in which blood and other bodily fluid were considered to be "humors" the proper balance of which maintained health...

).

As with much of the imperial army's organisation, it was Augustus who, drawing on the evolved but ad hoc practices of the Republican army, established systematic medical services for the army, with a formal medical hierarchy and the construction of large, fully staffed and well-supplied military hospitals (valetudinaria) in legionary bases e.g. the fully excavated hospital at Castra Vetera (Xanten, Rhineland).

In overall charge of the legion's medical staff and services was the legion's executive officer, the praefectus castrorum. Directly under him was the optio valetudinarii, or director of the hospital in the legionary fortress, who would have overall charge of its administration and staff. However, the clinical head of the legion's medical service was the chief physician, called simply the Medicus (the capital "M" here is used to distinguish from several other ranks of medicus). Most often an ethnic-Greek from the eastern part of the Empire, the Medicus was generally a highly qualified practitioner, occasionally even a published academic. The most notable example is Pedanius Dioscorides

Pedanius Dioscorides

Pedanius Dioscorides was a Greek physician, pharmacologist and botanist, the author of a 5-volume encyclopedia about herbal medicine and related medicinal substances , that was widely read for more than 1,500 years.-Life:...

, an army surgeon in the time of Nero, who published Materia Medica
Materia medica
Materia medica is a Latin medical term for the body of collected knowledge about the therapeutic properties of any substance used for healing . The term 'materia medica' derived from the title of a work by the Ancient Greek physician Pedanius Dioscorides in the 1st century AD, De materia medica libre...

, which remained for centuries the standard textbook on medicine. The rank of the Medicus is uncertain, but was probably on a par with the military tribunes i.e. equestrian. In many cases, the Medicus served a short commission, in the role of senior medical consultant, and then returned to civilian life.

Reporting to the chief physician were 10 medici ordinarii, qualified medics who were charged with the care of the men of each cohort. These held the rank of centurion. These were trained to handle the whole range of troops' medical problems, but specialists are attested e.g. medicus chirurgus (surgeon) and a medicus ocularis (ophthalmologist) in the classis Britannica
Classis Britannica
The Classis Britannica was a provincial naval fleet of the navy of ancient Rome. Its purpose was to control the English Channel and the waters around the Roman province of Britannia...

(Channel fleet). Underneath the ordinarii were medical orderlies, some of whom held the rank of principales, the rest as milites immunes. The latter included capsarii (wound-dressers, from capsa, a type of box in which they carried bandages) and seplasarii ("ointment-men"), who administered medicines.

Auxiliary regiments had their own medics, although on a smaller scale than a legion's. Because of the smaller size of units, there was no equestrian chief physician, but a medicus ordinarius. Also attested are medics who ranked as principales, including a veterinarius in charge of animal welfare, as well as immunes on the bottom rung.

From Greek medical science, Roman army medics inherited a wide knowledge of the medicinal properties of plants and herbs e.g. centaury, which was effective in healing wounds and eye diseases. Forts received regular supplies of medicines, and medics also composed herbal remedies themselves. Remains of at least 5 medicinal plants have been found in fort sites, suggesting that herb-gardens were cultivated inside fort precincts.

On the battlefield, medics and orderlies would be on hand behind the lines to treat injured soldiers on the spot. Using a wide range of sophisticated surgical instruments, medics would promptly remove extraneous bodies such as arrow- and spear-heads, clean and disinfect wounds using clean water and medicated wine or beer and stitch them. Orderlies would then bandage them. Speed in cleaning, closing and bandaging the wound was critical, as, in a world without antibiotics, infection was the gravest danger faced by injured troops, and would often result in a slow, agonising death.

Equipment

The basic equipment of an imperial foot-soldier was essentially the same as in the manipular Roman army of the Republic: metal armour cuirass, metal helmet, shield and sword. However, specially protective armour - the lorica segmentata
Lorica segmentata
The lōrīca segmentāta was a type of segmented armour almost exclusively used in the Roman Empire, but the Latin name was first used in the 16th century...

and the scutum
Scutum (shield)
Scutum is the Latin word for "shield", although it has in modern times come to be specifically associated with the rectangular, semi-cylindrical body shield carried by Roman legionaries.-History:...

, a rectangular shield - was developed for legionaries, although apparently not made available to auxiliaries.

Weapons manufacture

In the 2nd century, there is evidence of fabricae (arms factories) inside legionary bases and even in the much smaller auxiliary forts, staffed mainly by the soldiers themselves. But, unlike for the Late Roman army

Late Roman army

The Late Roman army is the term used to denote the military forces of the Roman Empire from the accession of Emperor Diocletian in 284 until the Empire's definitive division into Eastern and Western halves in 395. A few decades afterwards, the Western army disintegrated as the Western empire...

of the 4th century onwards, there is no evidence, literary or archaeological, of fabricae outside military bases and staffed by civilians during the Principate (although their existence cannot be excluded, as no archaeological evidence has been found for the late fabricae either).

Armour

Lorica segmentata: Modern tests have shown that this lorica provided better protection to weapon-blows and missile-strikes than the other types of metal armour commonly used by Roman troops, chain-mail (hamata) or scale (squamata), being virtually impenetrable by ancient weapons. However, historical re-enactors have found replicas of the lorica uncomfortable due to chafing and could only wear them for relatively short periods. It was also more expensive to manufacture and difficult to maintain due to its complex design of separate strips held together by braces and hooks.

The bas-reliefs of Trajan's Column

Trajan's Column

, a monument erected in 113 in Rome to commemorate the conquest of Dacia

Dacia

In ancient geography, especially in Roman sources, Dacia was the land inhabited by the Dacians or Getae as they were known by the Greeks—the branch of the Thracians north of the Haemus range...

by Emperor Trajan

Trajan

(r. 97–117), are a key source for Roman military equipment. Auxilia are generally shown wearing, chain-mail or simple leather corslet

Corslet

A corslet is defined by the Oxford English Dictionary as "a piece of defensive armour covering the body." In Ancient Greek armies, the 'hoplite', or heavy infantryman, wore a bronze corslet or known as the thorax to protect his upper body. The corslet consisted of two plates connected on the sides...

s, and carrying oval shields (clipei). Legionaries are depicted wearing lorica segmentata at all times (whether in combat or in other activities, such as construction) and with curved rectangular shields. But the figures in Trajan's Column are highly stereotyped, in order to distinguish clearly between different types of troops. On another Trajanic monument, the Adamclisi Tropaeum

Tropaeum Traiani

, the lorica segmentata does not appear at all, and legionaries and auxilia alike are depicted wearing either chain-mail or scales. There is general recognition that the Adamclisi monument is a more accurate portrayal of normality, with the segmentata used rarely, maybe only for set-piece battles and parades. It has been suggested that the lorica may have been used by auxiliaries also. But there is no firm evidence for this. Traces of this type of armour have been found in forts in Raetia

Raetia

from a time when no legions were stationed in the province. But these may simply have been left behind by legionaries on temporary detachment. Furthermore auxilia are nowhere depicted wearing such armour.

The provision of more protective and expensive armour to legionaries was probably due to non-military reasons: the army was highlighting their social superiority, just as it did with higher pay. During the 3rd century, when all peregrini were granted citizenship, and therefore legionaries lost their social superiority, the lorica segmentata and the rectangular shield disappeared.

During the 3rd century, the segmentata appears to have been dropped and troops are depicted wearing chain mail

Chain Mail

"Chain Mail" is a single by Mancunian band James, released in March 1986 by Sire Records, the first after the band defected from Factory Records. The record was released in two different versions, as 7" single and 12" EP, with different artworks by John Carroll and, confusingly, under different...

(mainly) or scale, the standard armour of the 2nd century auxilia. Officers generally seem to have worn bronze or iron cuirasses, as during the Republic, together with traditional pteruges
Pteruges
Pteruges refers to the decorative skirt of leather or fabric strips worn around the waists of Roman and Greek warriors and soldiers, as well as the similarly-fashioned epaulette-like strips worn on the shoulders or later, especially in the Middle East during the Middle Ages, the back of the...

.

Helmets

In the Julio-Claudian era (30 BC- AD 69), it appears that soldiers continued to use the types of helmet used by the army of the Republic since about 250 BC: the Montefortino

Montefortino helmet

The Montefortino helmet was a type of Celtic, and later Roman, military helmet used from around 300 BC through the 1st century AD with continuing modifications...

-type and Coolus

Coolus helmet

The Coolus helmet was a type of ancient Roman helmet. It was produced from brass and, like the Montefortino type with which it co-existed, was a descendent of Celtic helmet types....

-type. From about 70 AD onwards, these were replaced by more sophisticated designs, the so-called "Imperial Italic" and "Imperial Gallic"

Imperial helmet

The Imperial helmet-type was a type of helmet worn by Roman legionaries; it replaced the Coolus type, and constituted the final evolutionary stage of the legionary helmet .-Sub-classification:...

types. The aim of these innovations was to increase protection, whilst not obstructing the soldier's senses and mobility.

The "Imperial Gallic"- type which predominated from about AD 70 onwards, is a good illustration. The helmet features hinged cheek-guards covering the largest possible part of the face without restricting the soldier's breathing, sight and shouting-range. A horizontal ridge across the front of the bowl acted both as nose- (and face)-guard and as reinforcement against downward cuts on the bowl. Ear-guards protrude from the side of the helmet, but do not obstruct hearing. A shallow neck-guard was angled to the bowl to prevent chafing against the metal cuirass.

Shields

The legionary scutum
Scutum (shield)
Scutum is the Latin word for "shield", although it has in modern times come to be specifically associated with the rectangular, semi-cylindrical body shield carried by Roman legionaries.-History:...

(derivation: It. scudo, Sp. escudo, Fr. ecu; Rom. scut), a convex rectangular shield, appeared for the first time in the Augustan era, replacing the oval shield of the army of the Republic. Shields, from examples found at Dura and Nydam, were of vertical plank construction, the planks glued, and faced inside and out with painted leather. The edges of the shield were bound with stitched rawhide, which shrank as it dried improving structural cohesion. It was also lighter than the edging of copper alloy used in earlier Roman shields.

The scutum disappeared during the 3rd century. All troops adopted the auxiliary oval (or sometimes round) shield (clipeus).

Hand weapons

The gladius hispaniensis
Gladius
Gladius was the Latin word for sword, and is used to represent the primary sword of Ancient Roman soldiers. Early ancient Roman swords were similar to those used by the Greeks. From the 3rd century BC, the Romans adopted swords similar to those used by the Celtiberians and others during the early...

(adopted by the Romans from an Iberian design, probably during the First Punic War

First Punic War

The First Punic War was the first of three wars fought between Ancient Carthage and the Roman Republic. For 23 years, the two powers struggled for supremacy in the western Mediterranean Sea, primarily on the Mediterranean island of Sicily and its surrounding waters but also to a lesser extent in...

(260-41 BC), was a short (median length: 460 mm) stabbing-sword that was designed for close-quarters fighting. It was standard for the Principate infantry (both legionary and auxiliary). The cavalry used the spatha
Spatha
The spatha was a type of straight sword, measuring between , in use throughout first millennium AD Europe, and in the territory of the Roman Empire until about 600 AD. Later swords from 600 AD to 1000 AD are recognizable derivatives, though they are not spathae.The spatha was used in gladiatorial...

(It. spada, French épée, Sp. espada, Rom. spada), a longer (median length: 760 mm) sword that allowed longer reach and easier swing.
The Roman Legions also carried a small side arm called a pugio
Pugio
The pugio was a dagger used by Roman soldiers as a sidearm. It seems likely that the pugio was intended as an auxiliary weapon, but its exact purpose to the soldier remains unknown for sure...

.

Missiles

Legionaries were equipped with the developed version of the pilum
Pilum
The pilum was a javelin commonly used by the Roman army in ancient times. It was generally about two metres long overall, consisting of an iron shank about 7 mm in diameter and 60 cm long with pyramidal head...

, a heavy javelin (throwing-spear) that had been used by Roman soldiers since around 250 BC. This weapon had lead counterweights to assist stability in flight and penetration; a barbed point to prevent withdrawal from flesh or shield; and a buckling shank to prevent it being thrown back. During the Republic, legionaries had been equipped with two of these, but now appear to have carried only one. Modern tests have shown the effective range of these javelins to be about 15m. It appears that auxiliaries were not equipped with a pilum, but with a light spear.

Archers of the imperial army were equipped with the recurved composite bow

Composite bow

as their standard. This was a sophisticated, compact and powerful weapon, suitable for mounted and foot archers alike (the cavalry version being more compact than the infantry's).

Clothing

In the 1st and 2nd centuries, a Roman soldier's clothes consisted of a single-piece, short-sleeved tunic whose hem reached the knees and special hob-nailed sandals (caligae). This attire, which left the arms and legs bare, had evolved in a Mediterranean climate and was not suitable for northern Europe in cold weather. In northern Europe, long-sleeved tunics, trousers (bracae), socks (worn inside the caligae) and laced boots were commonly worn in winter from the 1st century. During the 3rd century, these items of clothing became much more widespread, apparently common in Mediterranean provinces also. However, it is likely that in warmer weather, trousers were dispensed with and caligae worn instead of socks and boots.

Logistics and supply

A critical advantage enjoyed by the imperial army over all its foreign enemies except the Parthians was a highly sophisticated organisation to ensure that the army was properly supplied on campaign. Like their enemies, the army would rely as much as possible on foraging for supplies when campaigning on enemy soil, but this was impractical in winter or even in summer if the land was barren or the enemy employed "scorched-earth" tactics. On Roman territory, foraging was obviously undesirable. The empire's complex supply organisation, as set up under Augustus, enabled the army to campaign in all seasons and in enemy territory. The quantities of food supplies required by an army on campaign were enormous and would require lengthy and elaborate planning for major campaigns. An imperial legion of 5,500 men would require a minimum of 12.5 tonnes of grain-equivalent every day. Thus, Agricola's Caledonian task-force at the Battle of Mons Graupius

Battle of Mons Graupius

According to Tacitus, the Battle of Mons Graupius took place in AD 83 or, less probably, 84. Gnaeus Julius Agricola, the Roman governor and Tacitus' father-in-law, had sent his fleet ahead to panic the Caledonians, and, with light infantry reinforced with British auxiliaries, reached the site,...

, around 25,000-strong, would have required, ca. 5,000 tonnes of grain-equivalent for three months' campaigning (plus fodder for the horses and pack-animals).

Such vast cargoes would be carried by boat as far as possible, by sea and/or river, and only the shortest possible distance overland. That is because transport on water was in ancient times much faster and more economical than on land (as it remains today, although the differential is smaller). Land transport of military supplies on the cursus publicus
Cursus publicus
The cursus publicus was the state-run courier and transportation service of the Roman Empire, later inherited by the Byzantine Empire. It was created by Emperor Augustus to transport messages, officials, and tax revenues from one province to another...

(imperial transport service) was typically on wagons (angariae), with a typical payload of 650 kg, drawn by two pairs of oxen. During the Principate, large vessels of several hundred tonnes' capacity were not uncommon. A vessel of, say 200 tonnes' capacity, with a 20-man crew, could carry the same load as ca. 300 wagons (which required 300 drivers and 1,200 oxen, plus pay for the former and fodder for the animals). A merchant ship would also, with a favourable wind, typically travel three times faster than the typical 3 km/h (2 mph) achieved by the wagons and for as long as there was daylight, whereas oxen could only haul for at most 5 hours per day. Thus freighters could easily cover 100 km (62 mi) per day, compared to ca. 15 km (9 mi) by the wagons. However, freighters of this capacity were propelled by square sails only and could progress only if there was a following wind, and could spend many days in port waiting for one. (However, coastal and fluvial freighters called actuariae combined oars with sail and had more flexibility, but smaller capacity, typically 30-40 tonnes). Maritime transport was also completely suspended for at least four months in the winter (as stormy weather made it too hazardous) and even during the rest of the year, shipwrecks were common. Even so, surviving shipping-rates show that it was cheaper to transport a cargo of grain by sea from Syria to Lusitania

Lusitania

Lusitania or Hispania Lusitania was an ancient Roman province including approximately all of modern Portugal south of the Douro river and part of modern Spain . It was named after the Lusitani or Lusitanian people...

(i.e. the entire length of the Mediterranean – and a ways beyond – ca. 5,000 km) than just 110 km (68 mi) overland.

Rivers constituted the vital supply arteries of the army. The establishment of the Rhine-Danube line as the European border of the empire was thus primarily due to its value as a major fluvial supply route, rather than its defensibility. The Rhine and Danube rivers were dotted with purpose-built military docks (portus exceptionales). The protection of supply convoys on the rivers was the responsibility of the fluvial flotillas (classes) under the command of the governors of provinces along the rivers: by AD 68, and perhaps from the time of Augustus, flotillas had been established on the Rhine (classis germanica) and Danube (classis Histrica).

A grain cargo would first be transported from its region of origin (e.g. from the northern Black Sea region or Egypt) by large seagoing freighter to a port at the mouth of a navigable river (e.g. the Danube). There it would be transferred to a number of smaller-capacity fluvial actuariae, which would transport it up-river to the grain-dock of a legionary fortress. The cargo would then be stored in a purpose-built granary within the fortress, where it would be safe from contamination or decay until it was needed. At the start of the campaigning season, it would be transported, still by river if possible, otherwise overland on wagons, to the tactical base used for operations. From there the campaigning legion would haul its own supplies to its current marching-camp. This was accomplished by a legion's mule-train of ca. 1,400 mules. (In addition, each of the legion's 600 contubernia - 8-man platoons who shared a campaign-tent - possessed one or two mules to carry its tent and other equipment).

The driving of the supply mule-train, and the care of the pack-animals, was in the hands of the legion's calones, professional camp-servants, most likely also on the army pay-roll, who accompanied the unit everywhere on campaign. These men were armed as light infantry and given basic combat-training, so that they could protect the mule-train and, in emergencies, the marching-camp itself. 200-300 calones would accompany each legion. (Calones were distinct from the personal servants - slaves or freedmen - whom officers generally took with them on campaign).

Fortifications

Beyond marching- and training-camps, the imperial army constructed various types of permanent fortifications: the legionary fortress (castra legionaria), designed to accommodate an entire legion of 5,000 - 6,000 men; the auxiliary fort (castellum), which normally held an auxiliary regiment of ca. 500 men; smaller forts for detachments; watch-towers and signal-stations; border barriers ditches or ramparts; city walls; infrastructure, such as bridges, grain and arms depots, etc.

In the 1st century, army fortifications predominantly consisted of earthen ramparts, topped by wooden parapets. Using commonly available materials, these were cheap and quick to construct and provided effective protection, especially from tribal enemies with no artillery or siegecraft skills. However, this type of fortification required constant maintenance: the rampart was vulnerable to soil-slides caused by torrential downpours and to the action of burrowing animals. The wooden parapet was vulnerable to rot, and to heavy missiles launched from catapults and, in dry conditions, to incendiary missiles. From around AD 50, when the empire's borders had begun to stabilise, the army started building fortifications of stone. These were much more expensive and time-consuming to erect, but were invulnerable to most natural threats (except earthquakes), provided much better protection against missiles and needed far less maintenance (many, such as Hadrian's Wall

Hadrian's Wall

, would still be largely intact today if they had not been pillaged for their dressed stones over the centuries). However, earth-and-wood fortifications remained an important part of the empire's defences until ca. AD 200, when stone fortifications became the norm.

Unit names, titles, standards and decorations

Unit names and numbers

The numbering of the legions is confusing. Several legions shared the same number with others. Augustus numbered the legions he founded himself from I, but also inherited numbers from his predecessors. Each emperor normally numbered the legions he raised himself starting from I. However, even this practice was not consistently followed. For example, Vespasian

Vespasian

kept the same numbers as before for legions he raised from disbanded units. Trajan

Trajan

's first legion was numbered XXX because there were 29 other legions in existence at the time it was raised; but the second Trajanic legion was given the sequential number II. XVII, XVIII and XIX, the numbers of the legions annihilated in the Teutoburg Forest

Battle of the Teutoburg Forest

The Battle of the Teutoburg Forest took place in 9 CE, when an alliance of Germanic tribes led by Arminius of the Cherusci ambushed and decisively destroyed three Roman legions, along with their auxiliaries, led by Publius Quinctilius Varus.Despite numerous successful campaigns and raids by the...

, were never used again. (These three legions are without titles, suggesting that in disgrace their titles may have been deliberately forgotten or left unmentioned). As a result of this somewhat chaotic evolution, the legion's title became necessary to distinguish between legions with the same number. The geographical titles indicate (a) the country a legion was originally recruited e.g. Italica = from Italy or (b) peoples the legion has vanquished e.g.Parthica = victorious over the Parthians. Legions bearing the personal name of an emperor, or of his gens (clan) (e.g. Augusta, Flavia) were either founded by that Emperor or awarded the name as a mark of special favour.

The nomenclature of the great majority of auxiliary regiments followed a standard configuration: unit type, followed by serial number, followed by name of the peregrini tribe (or nation) from whom the regiment was originally raised, in the genitive (possessive) plural case e.g. cohors III Batavorum ("3rd Cohort of Batavi"); cohors I Brittonum ("1st Cohort of Britons"). Some regiments combine the names of two peregrini tribes, most likely after the merger of two previously separate regiments e.g. ala I Pannoniorum et Gallorum ("1st Wing of Pannonians and Gauls"). A minority of regiments are named after an individual, mostly after the first prefect of the regiment e.g. ala Sulpicia (presumably named after a prefect whose middle (gens) name was Sulpicius). The latter is also an example of regiments that did not have a serial number.

Titles

Legions often carried several titles, awarded after successive campaigns, normally by the ruling emperor e.g. XII Fulminata
Legio XII Fulminata
Legio duodecima Fulminata , also known as Paterna, Victrix, Antiqua, Certa Constans, and Galliena, was a Roman legion, levied by Julius Caesar in 58 BC and which accompanied him during the Gallic wars until 49 BC. The unit was still guarding the Euphrates River crossing near Melitene at the...

also boasted: paterna ("senior"), victrix ("victorious"), antiqua ("venerable"), certa constans ("reliable, steadfast") and Galliena ("(the emperor) Gallienus

Gallienus

Gallienus was Roman Emperor with his father Valerian from 253 to 260, and alone from 260 to 268. He took control of the Empire at a time when it was undergoing great crisis...

's favourite"). Pia fidelis ("dutiful, loyal"), fidelis constans and others were titles awarded to several legions, sometimes several times to the same legion.

Auxiliary regiments were often rewarded for meritorious service by the grant of an honorific title. The most sought-after title was the prestigious c.R. (civium Romanorum = "of Roman citizens"). In the latter case, all the regiment's members at the time, but not their successors, would be granted Roman citizenship. But the regiment would retain the c.R. title in perpetuity. Another common title was the gens name of the emperor making the award (or founding the regiment) e.g. Ulpia: the gens name of Trajan

Trajan

(Marcus Ulpius Traianus r.98–117). Other titles were similar to those given to the legions e.g. pia fidelis (p.f. = "dutiful and loyal").

Standards

Each tactical unit in the imperial army, from centuria upwards, had its own standard. This consisted of a pole with a variety of adornments that was borne by dedicated standard-bearers who normally held the rank of duplicarius. Military standards had the practical use of communicating to unit members where the main body of the unit was situated, so that they would not be separated, in the same way that modern tour-group guides use umbrellas or flags. But military standards were also invested with a mystical quality, representing the divine spirit (genius) of the unit and were revered as such (soldiers frequently prayed before their standards). The loss of a unit's standard to the enemy was considered a terrible disgrace, which could only be fully expunged by its recovery.

The standard of a centuria was known as a signum, which was borne by the unit's signifer. It consisted of a pole topped by either an open palm of a human hand or by a spear-head. The open palm is suggested to have derived from the days when the smallest tactical unit was called a maniple (manipulus = "handful"). The poles were adorned with 2 to 6 silver discs (the significance of which are uncertain). In addition, the pole would be adorned by a variety of cross-pieces (including, at bottom, a crescent-moon symbol and a tassel). The standard would normally sport a cross-bar with tassels.

The standard of a Praetorian cohort or an auxiliary cohort or ala was known as a vexillum
Vexillum
The vexillum was a flag-like object used in the Classical Era of the Roman Empire. The word is itself a diminutive for the Latin word, velum, sail, which confirms the historical evidence that vexilla were literally "little sails" i.e. flag-like standards...

or banner. This was a square flag, normally red in colour, hanging from a crossbar on the top of the pole. Stitched on the flag would be the name of the unit and/or an image of a god. An exemplar found in Egypt bears an image of the goddess Victory on a red background. The vexillum was borne by a vexillarius. A legionary detachment (vexillatio) would also have its own vexillum. Finally, a vexillum traditionally marked the commander's position on the battlefield. The exception to the red colour appears to have been the Praetorian Guard, whose vexilla, similar to their clothing, favoured a blue background.

From the time of Marius

Gaius Marius

Gaius Marius was a Roman general and statesman. He was elected consul an unprecedented seven times during his career. He was also noted for his dramatic reforms of Roman armies, authorizing recruitment of landless citizens, eliminating the manipular military formations, and reorganizing the...

(consul 107 BC), the standard of a legion was its aquila
Aquila (Roman)
The Aquila was the eagle standard of a Roman legion, carried by a special grade legionary known as an Aquilifer. One eagle standard was carried by each legion.-History:...

("eagle"). The pole was surmounted by a sculpted eagle of solid gold, or at least gold-plated silver. Otherwise the pole was unadorned, save by metal thunderbolts under the eagle. No exemplar of a military eagle has ever been found. The eagle was borne by the aquilifer, the legion's most senior standard-bearer. So important were legionary eagles as symbols of Roman military prestige and power, that the imperial government would go to extraordinary lengths to recover those captured by the enemy. This would include launching full-scale invasions of the enemy's territory, sometimes decades after the eagles had been lost e.g. the expedition in 28 BC by Marcus Licinius Crassus against Genucla (Isaccea, near modern Tulcea

Tulcea

Tulcea is a city in Dobrogea, Romania. It is the administrative center of Tulcea county, and has a population of 92,379 as of 2007. One village, Tudor Vladimirescu, is administered by the city.- History :...

, Rom., in the Danube delta region), a fortress of the Getae

Getae

The Getae was the name given by the Greeks to several Thracian tribes that occupied the regions south of the Lower Danube, in what is today northern Bulgaria, and north of the Lower Danube, in Romania...

, to recover standards lost 33 years earlier by Gaius Antonius

Gaius Antonius Hybrida

Gaius Antonius Hybrida was a politician of the Roman Republic. He was the second son of Marcus Antonius Orator and brother of Marcus Antonius Creticus; his mother is unknown. He was the uncle of the famed triumvir Mark Antony....

, an earlier proconsul

Proconsul

of Macedonia

Macedonia (Roman province)

.

Under Augustus, it became the practice for legions to carry portraits (imagines) of the ruling emperor and his immediate family members. An imago was usually a bronze bust carried on top of a pole like a standard by an imaginifer.

From around the time of Hadrian (r. 117-38), some auxiliary alae adopted the dragon-standard (draco) commonly carried by Sarmatian cavalry squadrons. This was a long cloth wind-sock attached to an ornate sculpture of an open dragon's mouth. When the bearer (draconarius) was galloping, it would make a strong hissing-sound.

Decorations

The Roman army awarded a variety of individual decorations (dona) for valour to its legionaries. Hasta pura was a miniature spear; phalerae were large medal-like bronze or silver discs worn on the cuirass; armillae were bracelets worn on the wrist; and torques

Torc

A torc, also spelled torq or torque, is a large, usually rigid, neck ring typically made from strands of metal twisted together. The great majority are open-ended at the front, although many seem designed for near-permanent wear and would have been difficult to remove. Smaller torcs worn around...

were worn round the neck, or on the cuirass. The highest awards were the coronae ("crowns"), of which the most prestigious was the corona civica, a crown made oak-leaves awarded for saving the life of a fellow Roman citizen in battle. The most valuable award was the corona muralis, a crown made of gold awarded to the first man to scale an enemy rampart. This was awarded rarely, as such a man hardly ever survived.

There is no evidence that auxiliary common soldiers received individual decorations like legionaries, although auxiliary officers did. Instead, the whole regiment was honoured by a title reflecting the type of award e.g. torquata ("awarded a torque") or armillata ("awarded bracelets"). Some regiments would, in the course of time, accumulate a long list of titles and decorations e.g. cohors I Brittonum Ulpia torquata pia fidelis c.R..

Everyday life

Soldiers generally spent only a fraction of their working lives on campaign. Most of their time was taken up with a wide range of other military and non-military duties.

Fort duties

Non-military duties on-site included the routine chores of fort life (cleaning, washing clothes and equipment, feeding horses and pack-animals) and working in the fort's fabrica (workshop where armour, weapons and other equipment were made and repaired). The army demanded high standards of personal hygiene and cleanliness from its troops, and provided them with the necessary sanitary facilities. Wells were excavated inside forts and aqueducts built to nearby springs to provide a continuous and plentiful supply of fresh, drinkable water. Latrines in the fort were continually flushed by gravity-flowing water, and elaborate drains and sewers would discharge the raw sewage into nearby streams and rivers.

An essential and burdensome activity was the procurement of the vast quantities of supplies that the regiment needed. For raw materials, the army purchased what it could locally, and imported the rest from elsewhere. The men of I Hispanorum veterana went as far afield (from Moesia Inferior) as Gaul to procure clothing and grain. For manufactured goods, the regiments would produce some of their needs themselves e.g. evidence of leather-tanning and beer-brewing at Vindolanda and nearby Catterick fort. The tablets attest the procurement of cereals, beer, animal fodder; manufactured goods such as clothing, nails and vehicle parts; raw materials such as stone, iron, lead, timber, animal hides.

Military duties

Routine military duties included patrolling, guard-duty, and weapons training. These were not limited to the regiment's base fort and its vicinity only: the Vindolanda tablets show that detachments of the unit could be deployed in several different locations at once: one renuntia shows a detachment of nearly half the effectives of cohors I Tungrorum deployed at another fort. A papyrus renuntia for cohors I Hispanorum veterana equitata in Moesia Inferior (AD 105) reports a cavalry turma on a scouting mission (exploratum) across the Danube.

As in today's armies, each day would begin with a roll-call parade (probably called a numeratio). Soldiers were kept at a high level of physical fitness by daily exercises and 20 miles (32.2 km) marches typically every 10 days, as well as regular, full-scale training-manoeuvres and mock-skirmishes. The latter would often be inspected by a high military official: the legatus legionis, the provincial governor, or even the emperor himself. Some forts contained drill-halls, permitting all-weather training. Combat-training and exercises were a central part of a soldier's weekly routine. One tablet probably contains a scathing report by an officer (himself probably a Rhineland German) about the progress of young local trainee cavalrymen in the cohors equitata: "on horseback, too many of the pathetic little Brits (Brittunculi) cannot swing their swords or throw their javelins without losing their balance".

Parades were another important part of a regiment's routine. Occasional parades included religious rites and purely military parades such as the rosaliae signorum (decoration of the standards) and demissio, when veterans were discharged after completing their term of service and awarded their diplomas of Roman citizenship.

Communications between forts, legionary fortresses and the provincial capital were critical. Despatch-riders (dispositi), normally equites cohortales, were stationed at mutationes (road-side stations where horses could be changed) to form relays to carry messages rapidly. Relays of fresh riders and horses, careering at full gallop, could maintain an average speed of 20 miles per hour (32 km/h). Thus an urgent despatch from the legionary base at Eboracum (York) to the provincial governor's headquarters in London, a distance of 200 miles (300 km), a journey of about ten days for a single rider and mount, could be delivered in just ten hours. When messages were even more urgent, visual signals were used. Strings of signal-stations in prominent locations would transmit messages using parabolic mirrors during the day and fire by night.

Police duties

Off-site duties included many routine police and even administrative tasks. Provincial governors had only a minimal administrative staff at their disposal, and no regular police force. They therefore relied on their troops for many such duties e.g. escorting the governor or other senior officials, patrolling highways, assisting and escorting tax collectors and military supply wagons, carrying official despatches, arresting wanted men. Thus a renuntia shows a detachment of 46 men of I Tungrorum on escort duty (singulares) with the provincial governor's staff.

Highways were routinely garrisoned and patrolled along their entire length. Small detachments of troops would be on duty at the way-stations: mutationes and mansio
Mansio
In the Roman Empire, a mansio was an official stopping place on a Roman road, or via, maintained by the central government for the use of officials and those on official business whilst travelling.-Background:The roads which traversed the Ancient World, were later surveyed,...

nes (large wayside inns, with accommodation, stables, taverna and baths). These stations may well be the 6 unidentified locations where small detachments of ca. 10 men, each under a centurion, were deployed according to a renuntia of cohors I Tungrorum. Troops on highway duty would check the identities and cargoes of road users as well as escort the vehicles of the cursus publicus
Cursus publicus
The cursus publicus was the state-run courier and transportation service of the Roman Empire, later inherited by the Byzantine Empire. It was created by Emperor Augustus to transport messages, officials, and tax revenues from one province to another...

(imperial transport service). This service was concerned with the transportation of official personnel and payloads: senior officials, tax revenues and wages for the troops, military supplies (usually conveyed in convoys of ox-drawn wagons) and official post. Such vehicles, especially the money-cars, were vulnerable to highway robbers e.g. one eques (cavalryman) of I Hispanorum veterana was reported killed by robbers in a renuntia. Troops would also assist agents of the procurator
Procurator (Roman fiscal)
A Roman fiscal procurator was the chief financial officer of a province of the Roman Empire during the Principate era...

(the senior financial official in the province) to collect the portorium, an imperial toll on the carriage of goods on public roads, payable whenever the goods crossed a toll-line.

Construction

The most important non-military activity of the Roman army was construction. The army was a large workforce of fit, disciplined men which also comprised hundreds of skilled craftsmen. Troops were on regular salaries anyway, so it was cheaper for the government to use them for building projects, if the security situation in the province allowed, than to hire private contractors. In fact, soldiers spent far more of their working lives on building-sites than on campaign and it would not be a huge exaggeration to describe an imperial legion as an armed construction-gang.

Soldiers built their own forts and fortifications and other military facilities e.g. Hadrian's Wall

Hadrian's Wall

itself was built by the army. But they also built up much of a province's Roman infrastructure: trunk Roman roads, bridges, docks, canals, aqueduct

Aqueduct

An aqueduct is a water supply or navigable channel constructed to convey water. In modern engineering, the term is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose....

s, entire new cities such as coloniae for veteran legionaries, public buildings (e.g. basilica

Basilica

The Latin word basilica , was originally used to describe a Roman public building, usually located in the forum of a Roman town. Public basilicas began to appear in Hellenistic cities in the 2nd century BC.The term was also applied to buildings used for religious purposes...

s and amphitheatre

Amphitheatre

An amphitheatre is an open-air venue used for entertainment and performances.There are two similar, but distinct, types of structure for which the word "amphitheatre" is used: Ancient Roman amphitheatres were large central performance spaces surrounded by ascending seating, and were commonly used...

s). The army also carried out large-scale projects to increase the land available for agriculture, such as forest clearance and draining marshes (e.g. the large-scale drainage of the Fens

The Fens

The Fens, also known as the , are a naturally marshy region in eastern England. Most of the fens were drained several centuries ago, resulting in a flat, damp, low-lying agricultural region....

in eastern England, which were probably developed as a huge imperial estate). The army also excavated many of the mines and quarries that produced the raw materials it needed for weapons and armour manufacture and for construction. Soldiers would supervise the slave-gangs that generally worked the mines, or mine themselves at times of urgent demand.

Most of the available evidence relates to legionary construction. The several construction-scenes on Trajan's Column show only legionaries working, with auxiliaries standing guard around them. On Hadrian's Wall, legionary stamps only have been found on building-materials, with no evidence of auxiliary involvement. Birley suggests that auxiliaries may have been used to excavate the vallum
Vallum
Vallum is a term applied either to the whole or a portion of the fortifications of a Roman camp. The vallum usually comprised an earthen or turf rampart with a wooden palisade on top, with a deep outer ditch...

, a large ditch which runs parallel to the Wall, and thus would not have left stamps on building-materials. But it is also possible that auxiliary regiments were tasked with maintaining security on the border during construction. However, the Vindolanda tablets attest to construction activity by auxiliaries e.g. one tablet refers to 12 soldiers detailed to work on the construction of a bath-house (balneum) at Vindolanda. Another possibly refers to the construction of a bridge elsewhere.

Social life

All the Vindolanda documents are written by officers, supporting the view that many of the lower ranks may have been illiterate. The language used is always Latin, usually of a reasonable standard. Most of the authors were Gauls, Britons or Germans, whose native languages were Celtic or Germanic, yet they wrote even to their relatives in Latin. This does not mean that they could no longer speak their native tongues, simply that those tongues never developed a written form. The tablets show that the commanding officer was addressed as domine ("master" or "lord", due to his equestrian rank) and soldiers of the same rank as frater ("brother") or collega ("comrade"). The letters show that an auxiliary soldier maintained friendships not just in his own regiment, but also in other regiments and even in the legions. Hunting was a favourite leisure activity, for the officers at least. It was more strenuous, dangerous and required far greater skill than today due to the lack of firearms: prey had to be brought down with arrows or spears.

Religion

Roman religion was polytheistic

Polytheism

Polytheism is the belief of multiple deities also usually assembled into a pantheon of gods and goddesses, along with their own mythologies and rituals....

and therefore readily accepted and absorbed many deities of the empire's subjects, the vast majority of whose cultures were also polytheistic. But there were limits: the Romans forbade cults whose beliefs or practices were considered incompatible with the basic tenets of Roman religion. For example, the Romans proscribed cults that practised human sacrifice

Human sacrifice

Human sacrifice is the act of killing one or more human beings as part of a religious ritual . Its typology closely parallels the various practices of ritual slaughter of animals and of religious sacrifice in general. Human sacrifice has been practised in various cultures throughout history...

, which was partly the reason why Druid

Druid

A druid was a member of the priestly class in Britain, Ireland, and Gaul, and possibly other parts of Celtic western Europe, during the Iron Age....

ism was banned under the emperor Tiberius (political considerations were also involved, namely that Druids were suspected of orchestrating native resistance to Roman rule in Gaul). Also banned was Christianity

Christianity

Christianity is a monotheistic religion based on the life and teachings of Jesus as presented in canonical gospels and other New Testament writings...

, de facto initially, as membership of the Christian church was not prohibited formally until the rule of Septimius Severus (197-211). A monotheistic religion, its followers refused to participate in the imperial cult

Imperial cult (ancient Rome)

The Imperial cult of ancient Rome identified emperors and some members of their families with the divinely sanctioned authority of the Roman State...

, the worship of the imagines (cult portraits or statues) of ruling and past emperors. The cult was used by the Romans in the same way as an oath of allegiance

Oath of allegiance

An oath of allegiance is an oath whereby a subject or citizen acknowledges a duty of allegiance and swears loyalty to monarch or country. In republics, modern oaths specify allegiance to the country's constitution. For example, officials in the United States, a republic, take an oath of office that...

is used by modern societies, as an affirmation of loyalty to the state. It was compulsory for all peregrini to make burnt sacrifice to the image of the ruling emperor at least once (certificates were issued to prove compliance). Refusal was considered treasonous and was punishable by death. Christians were also widely suspected, through a misunderstanding of baptism

Baptism

In Christianity, baptism is for the majority the rite of admission , almost invariably with the use of water, into the Christian Church generally and also membership of a particular church tradition...

and the eucharist

Eucharist

The Eucharist , also called Holy Communion, the Sacrament of the Altar, the Blessed Sacrament, the Lord's Supper, and other names, is a Christian sacrament or ordinance...

, of practicing clandestine ritual murder of infants (by drowning) and cannibalism

Cannibalism

Cannibalism is the act or practice of humans eating the flesh of other human beings. It is also called anthropophagy...

respectively, violating two more Roman taboos.

In theory, soldiers were only permitted to honour such non-Roman gods as had been officially approved by the collegium pontificum
College of Pontiffs
The College of Pontiffs or Collegium Pontificum was a body of the ancient Roman state whose members were the highest-ranking priests of the polytheistic state religion. The college consisted of the Pontifex Maximus, the Vestal Virgins, the Rex Sacrorum, and the flamines...

("Board of High Priests") in Rome, which regulated the state religion. The board would assess whether a foreign cult was acceptable. If so, by the process of interpretatio Romana, a non-Roman god was officially annexed to a Roman god on the basis of shared characteristics e.g. Mars

Mars (mythology)

Mars was the Roman god of war and also an agricultural guardian, a combination characteristic of early Rome. He was second in importance only to Jupiter, and he was the most prominent of the military gods worshipped by the Roman legions...

Toutates

Toutatis

Toutatis or Teutates was a Celtic god worshipped in ancient Gaul and Britain. On the basis of his name's etymology, he has been widely interpreted to be a tribal protector. Today, he is best known under the name Toutatis through the Gaulish catchphrase "By Toutatis!", invented for the Asterix...

, the assimilation of a Gallic deity to the Roman god of war. In practice, off-duty soldiers were allowed to follow whatever cults they pleased, providing they were not specifically prohibited. Many surviving military dedications, especially those offered by the lower ranks, are to non-Roman deities alone.

Soldiers were, however, required to participate in a number of official Roman religious rites held by their regiment at regular times in the year. These included religious parades in honour of the most important Roman gods, especially Jupiter

Jupiter (mythology)

In ancient Roman religion and myth, Jupiter or Jove is the king of the gods, and the god of the sky and thunder. He is the equivalent of Zeus in the Greek pantheon....

, the supreme god of the Roman pantheon: many altars and tombstones dedicated by the military

Roman military tombstones

are headed with the letters IOM (Iovi Optimo Maximo: "to Jupiter the Best and Greatest"); Mars, the god of war; and Minerva

Minerva

Minerva was the Roman goddess whom Romans from the 2nd century BC onwards equated with the Greek goddess Athena. She was the virgin goddess of poetry, medicine, wisdom, commerce, weaving, crafts, magic...

, a goddess also associated with war. These parades were probably accompanied by animal sacrifices and feasting. Another important regimental cult was emperor-worship. Parades were held on imperial birthdays, when the imagines of the ruling emperor and of deified previous emperors would be saluted and offered sacrifices by the prefect of the regiment.

Outside of the regimental ceremonies, soldiers revered a vast array of deities. These can be divided into three categories: Roman gods; their own native gods, such as the Thracian hero

Hero

A hero , in Greek mythology and folklore, was originally a demigod, their cult being one of the most distinctive features of ancient Greek religion...

which is often represented on the tombstones of Thracian veterans as a mounted warrior spearing a beast (or man) on the ground; and the local gods of the province in which they served, such as the cult of Coventina

Coventina

Coventina was a Romano-British goddess of wells and springs. She is known from multiple inscriptions at one site in Northumberland county of the United Kingdom, an area surrounding a wellspring near Carrawburgh on Hadrian's Wall...

in Britain. Coventina was a British nymph

Nymph

A nymph in Greek mythology is a female minor nature deity typically associated with a particular location or landform. Different from gods, nymphs are generally regarded as divine spirits who animate nature, and are usually depicted as beautiful, young nubile maidens who love to dance and sing;...

associated with springs. Several dedications to her have been found e.g. those offered by the garrison of the auxiliary fort at Carrawburgh

Carrawburgh

Carrawburgh is a settlement in Northumberland. In Roman times, it was the site of a 3½ acre auxiliary fort on Hadrian's Wall called Brocolitia, Procolita, or Brocolita This name is probably based on the Celtic name for the place, and one possible translation put forward is 'badger holes'...

(on Hadrian's Wall).

From the 2nd century onwards, Eastern mystery cults, centred on a single deity (though not necessarily monotheistic) and based on sacred truths revealed only to the initiated, spread widely in the empire, as polytheism underwent a gradual, and ultimately terminal, decline. One such cult, that of Sol Invictus

Sol Invictus

Sol Invictus was the official sun god of the later Roman empire. In 274 Aurelian made it an official cult alongside the traditional Roman cults. Scholars disagree whether the new deity was a refoundation of the ancient Latin cult of Sol, a revival of the cult of Elagabalus or completely new...

("The Invincible Sun"), was designated as the official army-cult by the emperor Aurelian

Aurelian

Aurelian , was Roman Emperor from 270 to 275. During his reign, he defeated the Alamanni after a devastating war. He also defeated the Goths, Vandals, Juthungi, Sarmatians, and Carpi. Aurelian restored the Empire's eastern provinces after his conquest of the Palmyrene Empire in 273. The following...

(r. 270-5) and remained such until the time of Constantine I

Constantine I

(r. 312-37). However, by far the most popular among the Roman military was Mithraism, centred on a deity called Mithras. The mainstream view is that this originated in the Persian cult of Mithra

Mithra

Mithra is the Zoroastrian divinity of covenant and oath. In addition to being the divinity of contracts, Mithra is also a judicial figure, an all-seeing protector of Truth, and the guardian of cattle, the harvest and of The Waters....

, but the salient features of the Roman cult are absent in the Avesta

Avesta

The Avesta is the primary collection of sacred texts of Zoroastrianism, composed in the Avestan language.-Early transmission:The texts of the Avesta — which are all in the Avestan language — were composed over the course of several hundred years. The most important portion, the Gathas,...

and other Iranian evidence. It is thus possible that the Roman cult was not connected to the Iranian (except perhaps that the deity's name was borrowed) and instead originated in the eastern provinces of the empire itself, most likely in Phrygia

Phrygia

In antiquity, Phrygia was a kingdom in the west central part of Anatolia, in what is now modern-day Turkey. The Phrygians initially lived in the southern Balkans; according to Herodotus, under the name of Bryges , changing it to Phruges after their final migration to Anatolia, via the...

. Mithraism was probably a medley of elements from various cults - hence its apparent adoption of a Persian deity-name, of the taurobolium
Taurobolium
In the Roman empire of the 2nd to 4th centuries, taurobolium referred to practices involving the sacrifice of a bull, which after mid-2nd century became connected with the worship of the Great Mother of the Gods; though not previously limited to her cultus, after 159 CE all private taurobolia...

ritual from the cult of Cybele

Cybele

Cybele , was a Phrygian form of the Earth Mother or Great Mother. As with Greek Gaia , her Minoan equivalent Rhea and some aspects of Demeter, Cybele embodies the fertile Earth...

, and of the Phrygian cap

Phrygian cap

The Phrygian cap is a soft conical cap with the top pulled forward, associated in antiquity with the inhabitants of Phrygia, a region of central Anatolia. In the western provinces of the Roman Empire it came to signify freedom and the pursuit of liberty, perhaps through a confusion with the pileus,...

. Based on secret initiation ceremonies and rites, this cult is attested, for example, by the discovery of a Mithraeum (Mithraic temple) at Carrawburgh fort near Hadrian's Wall. Membership, according to the written evidence of dedications in Nida (Heddernheim

Heddernheim (Frankfurt am Main)

Heddernheim is a district or Stadtteil of Frankfurt am Main, Germany. It is part of the Ortsbezirk Nord-West, and is subdivided into the Stadtbezirke Heddernheim-Ost and Heddernheim-West. Heddernheim was first mentioned in documents in 801 as Phetterenheim...

), was not restricted according to social standing.

Christianity was much less common amongst the military until it was accorded favoured-cult status by Constantine I in the early 4th century. Nevertheless, it probably had some clandestine followers in the military during the 2nd and 3rd centuries, especially in the East, where it had spread widely. The discovery of a Christian house church

House church

House church, or "home church", is used to describe an independent assembly of Christians who gather in a home. Sometimes this occurs because the group is small, and a home is the most appropriate place to gather, as in the beginning phase of the British New Church Movement...

with the earliest Christian paintings extant (early 3rd century) at the fortress town of Dura-Europos

Dura-Europos

Dura-Europos , also spelled Dura-Europus, was a Hellenistic, Parthian and Roman border city built on an escarpment 90 m above the right bank of the Euphrates river. It is located near the village of Salhiyé, in today's Syria....

in Syria may indicate a Christian element in that town's garrison.

Deployment in the 2nd century

IMPERIAL ROMAN ARMY: Summary of known deployments c. AD 130
! Province !! Approx. modern
equivalent !! *Alae*
(no. *mill.*) !! *Cohortes*
(no. *mill.*) !! Total
aux. units !! Auxiliary
infantry !! Auxiliary
cavalry* !! No.
legions !! Legionary
infantry !! Legionary
cavalry !! TOTAL
GARRISON
Britannia	England/Wales	11 (1)	45 (6)	56	25,520	10,688	3	16,500	360	53,068
Rhine Frontier
Germania Inferior	S Neth/NW Rhineland	6	17	23	8,160	4,512	2	11,000	240	23,912
Germania Superior	Pfalz/Alsace	3	22 (1)	25	10,880	3,336	2	11,000	240	25,456
Danube Frontier
Raetia/Noricum	S Ger/Switz/Austria	7 (1)	20 (5)	27	11,220	5,280	1	5,500	120	22,120
Pannonia (Inf + Sup)	W Hungary/Slovenia	11 (2)	21 (4)	32	11,360	8,304	3	16,500	360	36,524
Moesia Superior	Serbia	2	10	12	4,800	1,864	2	11,000	240	17,904
Moesia Inferior	N Bulgaria/coastal Rom	5	12	17	5,760	3,520	1	5,500	120	14,900
Dacia (Inf/Sup/Poroliss)	Romania	11 (1)	32 (8)	43	17,920	7,328	2	11,000	240	36,488
Eastern Frontier
Cappadocia	Central/East Turkey	4	15 (2)	19	7,840	3,368	3	16,500	360	28,068
Syria (inc Judaea/Arabia)	Syria/Leb/Palest/Jordan/Israel	12 (1)	43 (3)	55	21,600	10,240	5	27,500	600	59,940
North Africa
Aegyptus	Egypt	4	11	15	5,280	3,008	2	11,000	240	19,528
Mauretania (inc Africa)	Tunisia/Algeria/Morocco	10 (1)	30 (1)	40	14,720	7,796	1	5,500	120	28,136
Internal provinces		2	15	17	7,200	2,224	1	5,500	120	15,044
TOTAL EMPIRE		88 (7)	293 (30)	381	152,260	71,468	28	154,000	3,360	381,088

Notes: (1) Table excludes ca. 4,000 officers (centurions and above). (2) Auxiliary cavalry nos. assumes 70% of cohortes were equitatae

Analysis

The table shows the importance of auxiliary troops in the 2nd century, when they outnumbered legionaries by 1.5 to 1.
The table shows that legions did not have a standard complement of auxiliary regiments and that there was no fixed ratio of auxiliary regiments to legions in each province. The ratio varied from six regiments per legion in Cappadocia to 40 per legion in Mauretania.
Overall, cavalry represented about 20% (including the small contingents of legionary cavalry) of the total army effectives. But there were variations: in Mauretania the cavalry proportion was 28%.
The figures show the massive deployments in Britannia and Dacia. Together, these two provinces account for 27% of the total auxilia corps.

Ancient

Arrian
Arrian
Lucius Flavius Arrianus 'Xenophon , known in English as Arrian , and Arrian of Nicomedia, was a Roman historian, public servant, a military commander and a philosopher of the 2nd-century Roman period...

Acies contra Alanos (ca. AD 140)
Caesar
Julius Caesar
Gaius Julius Caesar was a Roman general and statesman and a distinguished writer of Latin prose. He played a critical role in the gradual transformation of the Roman Republic into the Roman Empire....

De Bello Gallico (ca. 50 BC)
Dio Cassius
Dio Cassius
Lucius Cassius Dio Cocceianus , known in English as Cassius Dio, Dio Cassius, or Dio was a Roman consul and a noted historian writing in Greek...

Roman History (ca. AD 240)
Livy
Livy
Titus Livius — known as Livy in English — was a Roman historian who wrote a monumental history of Rome and the Roman people. Ab Urbe Condita Libri, "Chapters from the Foundation of the City," covering the period from the earliest legends of Rome well before the traditional foundation in 753 BC...

Ab Urbe Condita
Ab urbe condita
Ab urbe condita is Latin for "from the founding of the City ", traditionally set in 753 BC. AUC is a year-numbering system used by some ancient Roman historians to identify particular Roman years...

(ca. AD 20)
Suetonius
Suetonius
Gaius Suetonius Tranquillus, commonly known as Suetonius , was a Roman historian belonging to the equestrian order in the early Imperial era....

De Vita Caesarum (ca. AD 120)
Tacitus
Tacitus
Publius Cornelius Tacitus was a senator and a historian of the Roman Empire. The surviving portions of his two major works—the Annals and the Histories—examine the reigns of the Roman Emperors Tiberius, Claudius, Nero and those who reigned in the Year of the Four Emperors...

Agricola
Agricola (book)
The Agricola is a book by the Roman historian Tacitus, written c 98, which recounts the life of his father-in-law Gnaeus Julius Agricola, an eminent Roman general. It also covers, briefly, the geography and ethnography of ancient Britain...

(ca. AD 100)
Tacitus
Tacitus
Publius Cornelius Tacitus was a senator and a historian of the Roman Empire. The surviving portions of his two major works—the Annals and the Histories—examine the reigns of the Roman Emperors Tiberius, Claudius, Nero and those who reigned in the Year of the Four Emperors...

Annales
Annals (Tacitus)
The Annals by Tacitus is a history of the reigns of the four Roman Emperors succeeding Caesar Augustus. The surviving parts of the Annals extensively cover most of the reigns of Tiberius and Nero. The title Annals was probably not given by Tacitus, but derives from the fact that he treated this...

(ca. AD 100)
Tacitus
Tacitus
Publius Cornelius Tacitus was a senator and a historian of the Roman Empire. The surviving portions of his two major works—the Annals and the Histories—examine the reigns of the Roman Emperors Tiberius, Claudius, Nero and those who reigned in the Year of the Four Emperors...

Historiae
Histories (Tacitus)
Histories is a book by Tacitus, written c. 100–110, which covers the Year of Four Emperors following the downfall of Nero, the rise of Vespasian, and the rule of the Flavian Dynasty up to the death of Domitian.thumb|180px|Tacitus...

(ca. AD 100)
Vegetius
Vegetius
Publius Flavius Vegetius Renatus, commonly referred to simply as Vegetius, was a writer of the Later Roman Empire. Nothing is known of his life or station beyond what he tells us in his two surviving works: Epitoma rei militaris , and the lesser-known Digesta Artis Mulomedicinae, a guide to...

De Re Militari
De Re Militari
De Re Militari , also Epitoma Rei Militaris, is a treatise by the late Latin writer Vegetius about Roman warfare and military principles as a presentation of methods and practices in use during the height of Rome's power, and responsible for that power...

(ca. AD 390)

Modern

Cambridge Ancient History (CAH) (1996): 2nd Ed Vol X The Augustan Empire (30BC - 69 AD)
Cambridge Ancient History (CAH) (2000): 2nd Ed Vol XI The High Empire (70-192)
Cambridge Ancient History (CAH) (2005): 2nd Ed Vol XII The Crisis of Empire (193-337)

Sources

Background: the Caesarian Roman army

Foundation of the imperial army under Augustus (30 BC - AD 14)

Legions

Auxilia

Praetorian Guard

Urban cohorts

German bodyguards

Imperial expansion and stasis

1st century

2nd century

3rd century

Army size and cost

Central command

Provincial command

Praetorian Guard

Legions

Auxilia

Cohors

Ala

Cohors equitata

Auxiliary specialised units

Heavily armoured lancers

Light cavalry

Camel troops

Archers

Slingers

Scouts

Irregular allied forces

Legions

Auxilia

Ranks, role and pay

Rankers (caligati)

Legions

Auxilia

Legions

Auxilia

Legions

Auxilia

Army medical services

Equipment

Weapons manufacture

Armour

Helmets

Shields

Hand weapons

Missiles

Clothing

Logistics and supply

Fortifications

Unit names, titles, standards and decorations

Unit names and numbers

Titles

Standards

Decorations

Everyday life

Fort duties

Military duties

Police duties

Construction

Social life

Religion

Deployment in the 2nd century

Ancient

Modern

External links

See also