t out to anticipate his
attack. After investing Byzantium he crossed over to Asia Minor and
defeated the forces of his rival near Cyzicus and Nicaea, forcing them to
withdraw south of the Taurus mountains. The Cilician Gates were forced and
Niger decisively beaten in a battle at Issus (194 A. D.). He tried to
escape into Parthia but was overtaken and killed. Severus advanced across
the Euphrates to punish the Parthian king for his support of Niger. He
occupied northern Mesopotamia, and made Nisibis a Roman colony and
frontier fortress (196 A. D.). In the same year Byzantium was taken, its
fortifications destroyed, and its inhabitants deprived of the right of
municipal organization. Severus had brought his Parthian campaign to a
hasty conclusion, for in the West Clodius Albinus, feeling his position
insecure, had assumed the title of Augustus and occupied Gaul. Severus now
elevated his eldest son Bassianus, better known as Caracalla, to the
position of Caesar with the additional title of _imperator designatus_,
and set out to meet the usurper. In a great battle at Lugdunum, in which
150,000 men are said to have fought on either side, the army of Severus
was victorious and Albinus fell by his own hand (197 A. D.). Many of his
adherents, including numerous senators, were put to death.

V. THE DYNASTY OF THE SEVERI, 197-235 A. D.

*The Parthian war of 197-199 A. D.* Severus was now unchallenged ruler of
the empire. Shortly after the defeat of Albinus, he returned to the East
and resumed hostilities against the Parthians, whose king, Vologases IV,
had taken advantage of his absence to invade Armenia and Mesopotamia and
was besieging Nisibis. Severus relieved the beleaguered town and pressed
on into the enemy's territory, where he sacked the two Parthian capitals,
Seleucia and Ctesiphon, in 198 A. D. By a peace arranged in the next year
northern Mesopotamia was ceded to Rome and was organized as a province
under a governor of equestrian rank.

*A **military monarchy**.* Septimius Severus was a native of Leptis in
Africa. He came from an equestrian family and had begun his official
career as an advocate of the _fiscus_. To secure the prestige of noble
lineage he caused himself to be proclaimed as the adopted son of Marcus
Aurelius, and took the latter's family name of Antoninus for himself and
his house. His rule was frankly autocratic in character and he made no
attempt to disguise the fact that his auth