Caracalla was Roman 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...

 from 198 to 217. The eldest son of 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...

, he ruled jointly with his younger brother Geta
Publius Septimius Geta
Geta , was a Roman Emperor co-ruling with his father Septimius Severus and his older brother Caracalla from 209 to his death.-Early life:Geta was the younger son of Septimius Severus by his second wife Julia Domna...

 until he murdered the latter in 211. Caracalla is remembered as one of the most notorious and unpleasant of emperors because of the massacres and persecutions he authorized and instigated throughout the Empire.

Caracalla's reign was also notable for the Constitutio Antoniniana
Constitutio Antoniniana
The Constitutio Antoniniana was an edict issued in 212 AD, by the Roman Emperor Caracalla...

(also called the Edict of Caracalla) , granting 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 all freemen throughout 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....

 for the purpose of increasing tax revenue, according to historian Cassius Dio.