URSINUS, ANTIPOPE. — When Pope Liberius died (September 366), while in the church of St Lawrence in Lucina the deacon DAMASUS was being canonically elected, in the Julian Basilica (Santa Maria in Trastevere) seven priests and three deacons elected the deacon URSINUS, who was immediately consecrated by the bishop of Tivoli.
The schism quickly degenerated into civil war, and Rome became the scene of bloody clashes. A group of Damasian partisans indeed besieged the Julian Basilica for three days and in the end prevailed: two were killed and many wounded; Ursinus and the two deacons were driven into exile. The priests who remained in Rome, however, continued to hold their own liturgical assemblies. To put an end to every cause of strife, these too were arrested, but their followers rescued them from the police and together they occupied the Liberian Basilica. The Damasians besieged them once more and succeeded in overpowering them in a mêlée in which 137 persons perished. Damasus remained master of the situation, and once calm was restored, in September 367 the exiles were allowed to return. The disorders, however, broke out again, and the city prefect was compelled to send Ursinus and his adherents back into exile. A group of fanatics, nevertheless, continued to gather in the basilica of St Agnes on the Via Nomentana; fresh tumults arose; the schismatics were then forbidden to assemble within a circuit of twenty miles from Rome. Ursinus, who meanwhile had been relegated to Cologne, obtained permission to reside in Milan, where he joined forces with the Arians and with Valens of Petau. Though far from Rome, he did not cease to cause trouble for Damasus and instigated the Jewish convert Isaac to bring a lawsuit against the Pope, who was however declared innocent. To prevent him from doing further harm, St Ambrose begged Emperor Gratian in a letter to put an end to the machinations of the schism (381). Ursinus soon afterwards died.