Constantius II, Flavius Julius (AD 317–361)

Roman emperor from 337, third son of Constantine the Great. After Constantine's death he became joint ruler with his brothers, Constantine II and Constans, and he was given Thrace, Macedonia, Greece, the Asiatic provinces, and Egypt to rule.

Throughout his reign Constantius was at war with the Persians, and was often defeated by them, notably in 348. Following the death of Constans I, he defeated the usurper Magnentius at Mursa on the River Drave 351 and in Gaul 353, becoming master of the whole empire. In 355 Constantius made his cousin Julian Caesar and commander in Gaul. In 357 Constantius visited Rome for the first time. He favoured the Arians, and banished the Orthodox bishops. When Julian was proclaimed emperor by his troops in Gaul, Constantius moved west to oppose him, but died near Tarsus in Cilicia.