St Julius was a Roman, and chosen Pope on the 6th of February in 337. The Arian bishops in the East sent to him three deputies to accuse St Athanasius, the zealous Patriarch of Alexandria. These accusations, as the order of justice required, Julius imparted to Athanasius, who thereupon sent his deputies to Rome; when, upon an impartial hearing, the advocates of the heretics were confounded and silenced upon every article of their accusation.
The Arians then demanded a council, and the Pope assembled one in Rome in 341. The Arians instead of appearing held a pretended council at Antioch in 341, in which they presumed to appoint one Gregory, an impious Arian, Bishop of Alexandria, detained the Pope’s legates beyond the time mentioned for their appearance; and then wrote to his Holiness, alleging a pretended impossibility of their appearing, on account of the Persian war and other impediments. The Pope easily saw through these pretences, and in a council at Rome examined the cause of St Athanasius, declared him innocent of the things laid to his charge by the Arians, and confirmed him in his see.
He also acquitted Marcellus of Ancyra, upon his orthodox profession of faith. He drew up and sent by Count Gabian to the Oriental Eusebian bishops, who had first demanded a council and then refused to appear in it, an excellent letter, which is looked upon as one of the finest monuments of ecclesiastical antiquity. Finding the Eusebians still obstinate, he moved Constans, Emperor of the West, to demand the concurrence of his brother Constantius in the assembling of a general council at Sardica in Illyricum. This was opened in May 347, and declared St Athanasius and Marcellus of Ancyra innocent, deposed certain Arian bishops, and framed twenty-one canons of discipline. St Julius reigned fifteen years, two months, and six days, dying on the 12th of April, 352.