Liberius, d. 366, pope (352-66), a Roman; successor of St. Julius I. At the beginning of his pontificate, the status of Athanasius was still disputed, and Liberius requested Emperor Constantius II to call the Council of Arles (353). Subdued by imperial favor toward Arianism, the papal legates signed against Athanasius, but Liberius refused to be coerced or bribed. He was banished to Thrace by Constantius, who set up an antipope, Felix. In 358, Liberius was permitted to return to Rome after signing a vaguely worded creed and repudiating communion with Athanasius. Felix was forced to retire. After Constantius died, Liberius openly avowed his orthodox position and reasserted the primacy of Rome as arbiter in matters of faith.