After Constantius had finished his dealings with the west in 357, he moved to Constantinople and sent his young cousin Julian with the rank of Caesar to check possible usurpers and barbarian attacks in Gaul. In 355 both Cologne and Trier were badly damaged. A senior army officer was deputed to keep an eye on the Caesar, and to see that he made no foolish military decisions. In the event the officer led an unwise campaign across the Rhine and was crushed, thereby leaving Julian a free hand. At Strasbourg in 357 Julian led his troops to success, enjoyed adulation from the legions, and himself composed a panegyric on his famous victory.
It was a remarkable achievement for a young man in his mid-twenties whose upbringing and education had been withdrawn and bookish. After Eusebius, successively of Nicomedia and Constantinople, had died in the winter of 341/2, Julian and his elder brother Gallus had been confined to an imperial palace and estate at Macellum, near Caesarea in Cappadocia. He was to be there for six years during which he served as a Reader in the church at Caesarea and with his brother funded the building of a martyr's shrine for St Mamas, a popular hero for the church at Caesarea (Basil, hom. 23; Greg. Naz. or. 44, 12). He knew his Bible well, better than his guardians, it was said (Eunapius, V. Soph. 473). He studied classical Greek literature and the liberal arts under a congenial tutor named Mardonios. He was able to borrow books from the opulent library of George, who in 357 was to be pressed into becoming Athanasius' rival as bishop of Alexandria, where he was singularly unloved by the city populace, both Christian and pagan. The news of Constantius' death in November 361 provoked the mob to lynch George; Julian immediately wrote disapproving of the murder but demanding George's library for himself, to which end torture should be used if necessary. In 347 Gallus was moved to Constantius' court, while Julian studied further first at Constantinople, then at Nicomedia. At that time the distinguished pagan rhetor Libanius was teaching in Nicomedia; Julian was not allowed to