The Western Schism, 1378-1417, when there was controversy over the true succession to the papacy. It began with the writings of Marsilius of Padua (c. 1275-c. 1342), who claimed that a pope is subject to a council of bishops, priests, and laymen. Urban VI was elected Pope on April 8, 1378, following the seventy-year Avignon residence of the papacy. He was a stern reformer and also harsh. The French cardinals in retaliation declared that Urban had not been validly elected and proceeded to elect Robert of Geneva as the antipope Clement VII (1378-94). Clement withdrew to Avignon and the Great Schism was in full swing. France, Scotland, and Spain gave their allegiance to Clement; England, Italy, Flanders, Hungary, Poland, and most of Germany followed Urban, who died in 1389. There followed a succession of lawful popes at Rome and antipopes at Avignon. The universities of Paris, Oxford, and Prague disputed how the impasse should be resolved. Finally pope and antipope were invited to a council at Pisa (1409); both declined and were declared deposed by the council, which proceeded to elect yet another antipope, Alexander V (1409-10). In desperation Emperor Sigismund of Germany appealed to the antipope John XXIII of Pisa, to call a general council at Constance, a German city on the Rhine. John agreed, and the council, later legitimized, was convened in 1414. It lasted four years and finally resolved the schism. The Pisan antipope John XXIII abdicated. Gregory XII, the true Roman Pontiff, having formally convoked the Council of Constance, sent his representatives, and then, for the good of the Church, freely resigned his office. The claim of Benedict XIII of Avignon was no longer worthy of serious consideration. The chair of Peter, vacant at last, was filled by the election, November 11, 1417, of Pope Martin V. The Great Schism was ended.