1414–18, council of the Roman Catholic Church, some of its sessions being reckoned as the 16th ecumenical council. It was summoned to end the Great Schism (see Schism, Great), in which three men were claiming to be pope—Gregory XII (since recognized as canonical pope), John XXIII (see Cossa, Baldassare), and Benedict XIII (see Luna, Pedro de). Reform of Christian life and extirpation of heresy were also aims of the convocation, which was called by John at the insistence of Holy Roman Emperor Sigismund. Sigismund chose Konstanz (Constance), an imperial city, as the meeting place. Church theologians tend to regard as ecumenical in character only those sessions of the council meeting after the convocation by Gregory XII, or the sessions following the election of Martin V.
During the council enormous crowds visited the city; there was much pageantry. The first session was in Nov., 1414; the 45th and last was on Apr. 22, 1418. The council was dominated by theologians, especially French, who held the conciliar theory (i.e., that councils held supreme power in the church and that even the pope was subject to their edicts) that had appeared at the Council of Pisa (see Pisa, Council of). The conciliarists John Gerson and Pierre d'Ailly were among the figures prominent at the council. Instead of the traditional assembly of bishops, the council was organized as a convention of nations (German, Italian, French, and English; the Spanish entered later), each nation having one vote. The decisions were made in caucuses of the nations between sessions.
The convention declared in the Articles of Constance (Apr. 6, 1415) that it was an ecumenical council and supreme in the church. Next it declared John deposed (May 29, 1415). Gregory XII, meanwhile, sent legates with a formal decree to convene a council; this was accepted by the convention, which then ceremonially declared the council convened; at the same time Gregory resigned the papacy (July 4, 1415). Benedict provided a hard problem; he would abdicate only if allowed to name his successor. At last, after a trial held in his absence, he was deposed (July 26, 1417). This ended the schism.
An elaborate method of electing the new pope was adopted, and the conclave soon agreed on Martin V (Nov. 11, 1417). The council, however, had already provided a plan to perpetuate its rule over the church by calling for frequent councils; furthermore, the modest reforms enacted by the council seemed designed to limit the pope's power of taxation and to protect the interests of the national clergy. Martin agreed to all enactments of the council—except, Catholic theologians argue, the council's extreme claim to supremacy—and signed concordats embodying these reforms with Germany, England, and the Latin countries. John Huss and Jerome of Prague were tried and burned at the stake for heresy. St. Bridget of Sweden was canonized.