Roman army
Overview
 
The Roman army is the generic term for the terrestrial armed forces deployed by the kingdom of Rome (to ca. 500 BC), the Roman Republic
Roman Republic
The Roman Republic was the period of the ancient Roman civilization where the government operated as a republic. It began with the overthrow of the Roman monarchy, traditionally dated around 508 BC, and its replacement by a government headed by two consuls, elected annually by the citizens and...

 (500-31 BC), 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....

 (31 BC - AD 476) and its successor, the Byzantine empire
Byzantine Empire
The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

 (476-1453). It is thus a term that spans approximately 2,000 years, during which the Roman armed forces underwent numerous permutations in composition, organization, equipment and tactics, while conserving a core of lasting traditions.
The development of the Roman army may be divided into the following 8 broad historical phases:

(1) The Early Roman army
Early Roman army
The Early Roman army refers to the army deployed by ancient Rome during its Regal Era and its early Republic, until ca. 300 BC, when the so-called "Polybian" or manipular legion was introduced....

of the Roman kingdom
Roman Kingdom
The Roman Kingdom was the period of the ancient Roman civilization characterized by a monarchical form of government of the city of Rome and its territories....

 and of the early Republic (to ca.
 
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