LAVIUS CLAUDIUS JULIANUS) (C. 331-363), com monly called JULIAN THE APOSTATE, Roman emperor, was born in Constantinople in 332 (probably), the son of Julius Constan tius and his wife Baslina, and nephew of Constantine the Great. Julian lost his mother not many months after he was born. In 337 Constantine died, and the whole of Julian's family, except his half-brother, Gallus, was murdered by the soldiers to ensure the undisputed succession of the sons of Constantine. Gallus was banished, but Julian was allowed to remain in Constantinople, where he was carefully educated under the supervision of the family eunuch, Mardonius, and of Eusebius, bishop of Nico media. About 341 Gallus was recalled, and the two brothers were removed to Macellum, a remote and lonely castle in Cappadocia. Julian was trained to the profession of the Christian religion ; but he became early attracted to the old faith, or rather to the idealized amalgam of paganism and philosophy which was current among his teachers, the rhetoricians. The old Hellenic world had an irresistible attraction for him. Love for its culture was, in Julian's mind, associated with loyalty to its religion.
A task of extreme difficulty awaited him beyond the Alps. During recent troubles the Alamanni and other German tribes had crossed the Rhine ; they had burned many flourishing cities, and extended their ravages far into the interior of Gaul. The internal
government of the province had also fallen into great confusion. In his first campaign, in 356, he co-operated with Constantius, who advanced from Raetia, while Julian moved up the left bank of the Rhine. The only notable fighting was Julian's successful defence of Sens at the end of the year. The next year he was by himself ; Barbatio, left to support him with a large force, deserted, and Julian extricated himself from great danger with a great vic tory at Strasbourg (357). This season saw the lower Rhine cleared as well. The year 358 was devoted to the recovery of the captures from Gaul beyond the Rhine and the re-organization of the frontier defences. In Gaul, Julian rebuilt the cities which had been laid waste, re-established the administration on a just and secure footing, and, as far as possible, lightened the taxes which weighed so heavily on the poor provincials. Paris was the usual residence of Julian during his government of Gaul, and his name has become inseparably associated with the early history of the city.
Meanwhile the inner circle of Constantius's court were doing their best to poison the emperor's mind against Julian. In 36o he received the emperor's orders withdrawing a number of troops for the renewed war with Persia, and putting them at once under a different command. Julian first objected, then submitted ; the soldiers themselves halted at Paris on the way east and proclaimed him emperor. He accepted, and at once tried to negotiate with Constantius, who was campaigning in the East. The message being disregarded, both sides prepared for a decisive struggle. After a march of unexampled rapidity through the Black forest and down the Danube, Julian reached Sirmium, and he was on the way to Constantinople when he received news of the death of Con stantius, who had set out from Syria to meet him, at Mopsucrene in Cilicia (Nov. 3, 361). Without further trouble Julian found himself everywhere acknowledged the sole ruler of the Roman empire ; it is even asserted that Constantius himself, on his death bed, had designated him his successor. Julian entered Constanti nople on Dec. II, 361.