John XXIII (antipope)

John XXIII (antipope) (1370?-1419), antipope (1410-1415). Born Baldassare Cossa in Naples, he studied law in Bologna and in 1402 became a cardinal deacon. He was a leader in the Council of Pisa in 1409, when Pope Gregory XII and Benedict XIII, an antipope, were deposed, and Alexander V was elected antipope to heal the Western Schism (see Schism, Great). When Alexander V died, Cossa succeeded him as John XXIII. John's principal sponsor was Louis, duke of Anjou, later Louis II of Naples, whose claim to the kingdom of Naples John supported. In 1413 John convoked a council in Rome, the chief accomplishment of which was the condemnation of the writings of two religious reformers, John Wycliffe, of England, and Jan Hus (John Huss), of Bohemia. At the Council of Constance, held from 1414 to 1418 to heal the schism in the Western church, John was forced, in 1415, to abdicate (see Constance, Council of). He resumed his original name and was confined in various German cities until 1418. Reconciled with Pope Martin V, whose election in 1417 ended the schism, Cossa was made cardinal bishop of Tusculum in 1419, five months before his death.