Baring-Gould’s sources: Greek Menæa on this day. Baronius and others have expressed surprise that the name of S. Proterius is inserted in no Western Martyrologies. Authority:—Evagrius, lib. iii. 13; Theophanes, the letters of Anatolius, Patr. of Constantinople, &c.

S. Proterius was the head of the orthodox party at Alexandria, when the patriarch [the title of the bishops of the great ancient sees: Rome, Constantinople, Alexandria, Antioch, Jerusalem] Dioscorus adopted Eutychian [followers of Eutyches, who said Christ had only a divine nature; condemned at Chalcedon in 451] views. That unprincipled and haughty prelate, knowing the esteem in which Proterius was held, made him arch-priest of his diocese; but as his heretical opinions became more evident, Proterius took decided steps to oppose him, and on the condemnation and deposition of Dioscorus by the Council of Chalcedon, in 452, he was ordained in his room. This led to a schism in the Church of Alexandria, the Catholics acknowledging Proterius, and the Eutychians holding with Dioscorus. The Eutychians were headed by two ecclesiastics, Timothy Ailurus, and Mongus, who had been excommunicated for heresy. In a tumult that broke out, Ailurus, having obtained consecration from two bishops of their faction, mounted the episcopal throne, and proclaimed himself sole patriarch of Alexandria. Proterius fled for safety to the baptistery of the Church of S. Quirinus, but the heretics broke in and stabbed him to death; then dragged his body through the streets, hacked it to pieces, and burnt it.