He 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 informations, 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, at which appeared St. Athanasius, Marcellus of Ancvra, and other orthodox prelates, who entreated the pope that he would cite their adversaries to appear. Julius accordingly sent them an order to repair to Rome within a limited time. They, instead of obeying, 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 pretenses, 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.