Council Of Constance, a council of the Roman Catholic church, opened Nov. 5, 1414, closed April 22, 1418. The great western schism had commenced with the antipope Clement VII. (Robert de Geneve), who fixed his residence at Avignon, and obtained the countenance of the French king. Urban VI. after his election bad been for nearly a year acknowledged as sole pope by the whole of Christendom; and he was succeeded by Boniface IX., Innocent VII., and Gregory XII. Robert de Geneve had as his successor Peter de Luna (Benedict XIII.), who maintained his claims and continued his schism until his death in 1424. The efforts made by politicians in church and state to remedy this division had failed up to the opening of the assembly in Constance. A council was held in Pisa in 1409, which took upon itself to depose both Gregory and Benedict, the pope and antipope; and a third contestant, Alexander V., was elected in their stead. This action is held by every canonist in the Roman Catholic church as utterly null in law. The rule is that there is no truly oecumenical council except such as are convened by the head of the church, and that the acts of no council in faith and morals have a binding force on the conscience save through the sanction of the pope.

The council of Pisa was not therefore acknowledged as oecumenical, and its action only increased the existing confusion. In 1410 the antipope Alexander V. died, and his place was filled by Baltassare Cossa (John XXIII). The great powers, headed by the emperor Sigismund, sought a remedy for the scandal in a meeting of the states general of Christendom. Gregory XII., the lawful pope, did not call it; and when it met, under the presidency of the anti-pope John XXIIL, it only embraced a comparatively small number of cardinals, patriarchs, archbishops, and bishops, with a multitude of inferior ecclesiastics and laymen. John XXIIL, called upon in the very first session to abdicate his dignity, bound himself by oath to do so, and then fled secretly from Constance, lest he should be held to his promise. In the perplexity caused by his flight, it was proposed to decree the superiority of the council above persons even of papal rank, with power to depose all who should refuse to obey the will of the assembly.

At length the antipope John was persuaded to resign (March, 1415), was subsequently deposed (May 29), and placed in confinement near Constance. Pope Gregory, who had already solemnly pledged himself to abdicate the moment the other contestants had done so, did not wait for the abdication of Peter de Luna; but giving to the lord of Rimini, Carlo Malatesta, full power as legate, sent him to assure the assembly of Constance that he was ready to make a full renunciation of the papal dignity. This was announced in the 13th session, June 15. On the acceptance of his proposition, a bull was issued by the pope convening the council from that date, and giving thenceforth to its acts a canonical validity; after which, in July, Gregory abdicated. Peter de Luna refusing to resign, and shutting himself up in the fortress of Peiliscola, near Valencia, the fathers of the council, after waiting 100 days for an answer, commanded the cardinals to enter the conclave. On Nov. 11, 1417, they chose Ottone Colonna, who took the name of Martin V. Regarding himself as the successor of Gregory XII., he issued a bull confirming the convocation, and further confirmed all that had been done concilianter (i. e., according to the canonical rules governing an oecumenical council) in matters of faith and morals, from the day of lawful convocation.

In the earlier sessions of the council the doctrines of Wycliffe were examined and condemned. John Huss also appeared, maintained his own tenets, and was condemned and executed (July 6, 1415). His disciple, Jerome of Prague, recanted, but having relapsed was also put to death (May 30, 1416).