Conciliar Movement at English => English (The Britannica Concise) Of Explained:
In Roman Catholicism, an effort to strengthen the authority of church councils over that of the papacy. Originally aimed at ending the Western Schism, the Conciliar Movement had its roots in legal and intellectual circles in the 13th cent. but emerged as a force at the Council of Pisa (1409), which elected a third pope in an unsuccessful attempt to reconcile the parties of the existing pope and antipope. A second council, the Council of Constance (1414-18), ended the schism by voiding all papal offices and electing a new pope. Participants hoped to play an ongoing role in the church, but the popes continued to seek supremacy, and the Council of Basel (1431-49) ended fruitlessly.