Severus or Septimius Severus (Lucius Septimius Severus)(sĕptĭmˈēəs sēvēˈrəs) [key], 146–211, Roman emperor (193–211), b. Africa. He was campaigning in Pannonia and Illyria when the emperor Commodus was murdered. His successor, Pertinax, lasted three months before he too was assassinated. The Pretorian guards arranged the succession of the weak Didius Julianus. With the empire in disarray, Severus marched on Rome. Proclaimed emperor, Severus went to the East to overthrow Pescennius Niger, the governor of Syria, who had also been proclaimed emperor by his legions. Severus defeated (194) the pretender. He took (196) Byzantium and subdued the rebellious Arabs of Mesopotamia. Returning to the West, he defeated (197) Clodius Albinus, another pretender, in Gaul and, returning eastward, attacked and expelled (198) the Parthians from Mesopotamia. In 208, Severus went to Britain. From there he harassed Scotland, but he died at York before completing his plans for a large invasion. Severus built a strong army, increasing the number of legions while eliminating the large commands that had been common for Rome, thus protecting himself against being overthrown while he protected Rome. He ruled with vigor and, when he found it useful, a calculated cruelty. Caracalla succeeded him.
See study by A. R. Birley (1971).