Sergius III, Pope, date of birth unknown; consecrated 29 Jan., 904; d. 14 April, 911. He was a Roman of noble birth and the son of Benedict. He became a strong upholder of the party opposed to Pope Formosus; as this party was not ultimately successful, the writings of its supporters, if they ever existed, have perished. Hence, unfortunately, most of our knowledge of Sergius is derived from his opponents. Thus it is by an enemy that we are told that Sergius was made Bishop of Caere by Formosus in order that he might never become Bishop of Rome. However, he seems to have ceased to act as a bishop after the death of Formosus, and was put forward as a candidate for the papacy in 898. Failing to secure election, he retired, apparently to Alberic, Count of Spoleto. Disgusted at the violent usurpation of the papal throne by Christopher, the Romans threw him into prison, and invited Sergius to take his place. Sergius at once declared the ordinations conferred by Formosus null; but that he put his two predecessors to death, and by illicit relations with Marozia had a son, who was afterwards John XI, must be regarded as highly doubtful. These assertions are only made by bitter or ill-informed adversaries, and are inconsistent with what is said of him by respectable contemporaries. He protected Archbishop John of Ravenna against the Count of Istria, and confirmed the establishment of a number of new sees in England. Because he opposed the errors of the Greeks, they struck his name from the diptychs, but he showed his good sense in declaring valid the fourth marriage of the Greek emperor, Leo VI. Sergius completely restored the Lateran Basilica, but he was buried in St. Peter's.
Liber Pontif., II, 236; Letters of Sergius in P. L., CXXXI; Letters of St. Nicholas I, the Mystic in Labbe, Concil., IX, 1246 sqq.; Fedele, Ricerche per la storia di Roma e del papato nel secolo X in Archivio Rom. di storia pat. (1910), 177 sqq.; Mann, Lives of the Popes in the early Middle Ages, IV (St. Louis, 1910), 119 sqq.
Horace K. Mann.