The Ecclesiastical History of Socrates Scholasticus 28On Account of the Charges against Athanasius, the Emperor convokes a Synod of Bishops at Tyre.

The emperor had ordered a Synod of bishops to be present at the consecration of the church which he had erected at Jerusalem. He therefore directed that, as a secondary matter, they should on their way first assemble at Tyre, to examine into the charges against Athanasius; in order that all cause of contention being removed there, they might the more peacefully perform the inaugural ceremonies in the dedication of the church of God. This was the thirtieth year of Constantine's reign, and sixty bishops were thus convened at Tyre from various places, on the summons of Dionysius the consul. As to Macarius the presbyter, he was conducted from Alexandria in chains, under a military escort; while Athanasius was unwilling to go thither, not so much from dread, because he was innocent of the charges made, as because he feared lest any innovations should be made on the decisions of the council at Nicaea; he was, however, constrained to be present by the menacing letters of the emperor. For it had been written him that if he did not come voluntarily, he should be brought by force.