1372–1436

The Great Western Schism, Jan Hus, and the Council of Constance

Under Catherine of Siena's influence, Gregory XI returned from Avignon to Rome in 1377 but soon died. The dictatorial Urban VI was elected in his place. Some cardinals declared the election invalid and elected Clement VII at Avignon. So began the Great Western Schism (1378–1417), during which Europe split its allegiance between two, and by 1409 even three, popes.

Jan Hus, rector of Prague University, was influenced by Wycliffe. He denounced clerical corruption and the sale of indulgences ('On the Church', 1413). Hus was excommunicated in 1412. He came to the Council of Constance (1414–1418), convened to end the schism, under Emperor Sigismund's safe-conduct. But he was arrested, refused to recant, and was burned on 6 July 1415.

His execution soon triggered the Hussite Wars in Bohemia (1420s–1430s). They ended with the Council of Basel's concessions on communion from the chalice (1436) and the formation of the Unity of the Brethren.

The Council of Constance itself deposed all three rival popes in 1417 and elected Martin V. It condemned 200 of Wycliffe's propositions and thus ended the schism. At the same time it produced conciliarism – the doctrine of a council's supremacy over the pope. This doctrine never took hold permanently: it was finally defeated by 1449 with the dissolution of the Council of Basel.