Severus proclaimed Caracalla co-ruler in , doing the same with his other son Geta in The two brothers briefly shared power after their father's death in , but Caracalla soon had Geta murdered by the Praetorian Guard and became sole ruler of the Roman Empire. Julia Domna had a significant share in governance, since Caracalla found administration to be mundane. His reign featured domestic instability and external invasions by the Germanic peoples.
Caracalla issued the Antonine Constitution Latin : Constitutio Antoniniana , also known as the Edict of Caracalla, which granted Roman citizenship to all free men throughout the Roman Empire. The edict gave all the enfranchised men Caracalla's adopted praenomen and nomen : "Marcus Aurelius". Other landmarks of his reign were the construction of the Baths of Caracalla , the second-largest bathing complex in the history of Rome, the introduction of a new Roman currency named the antoninianus , a sort of double denarius , and the massacres he ordered, both in Rome and elsewhere in the empire.
In , Caracalla began a campaign against the Parthian Empire. He did not see this campaign through to completion due to his assassination by a disaffected soldier in Macrinus succeeded him as emperor three days later. The ancient sources portray Caracalla as a cruel tyrant; his contemporaries Cassius Dio c.
In the 12th century, Geoffrey of Monmouth started the legend of Caracalla's role as king of Britain. Later, in the 18th century, the works of French painters revived images of Caracalla due to apparent parallels between Caracalla's tyranny and that ascribed to king Louis XVI r.
Modern works continue to portray Caracalla as an evil ruler, painting him as one of the most tyrannical of all Roman emperors. Caracalla's name at birth was Lucius Septimius Bassianus. He was renamed Marcus Aurelius Antoninus at the age of seven as part of his father's attempt at union with the families of Antoninus Pius and Marcus Aurelius.
