The Western Schism, also known as the Papal Schism, the Vatican Standoff, the Great Occidental Schism, or the Schism of 1378 (Latin: Magnum schisma occidentale, Ecclesiae occidentalis schisma), was a split within the Catholic Church lasting from 1378 to 1417 in which bishops residing in Rome and Avignon both claimed to be the true pope, and were joined by a third line of Pisan claimants in 1409. The schism was driven by personalities and political allegiances, with the Avignon papacy being closely associated with the French monarchy. These rival claims to the papal throne damaged the prestige of the office.
The papacy had resided in Avignon since 1309, but Pope Gregory XI returned to Rome in 1377. However, the Catholic Church split in 1378 when the College of Cardinals declared it had elected both Urban VI and Clement VII pope within six months of Gregory XI's death. After several attempts at reconciliation, the Council of Pisa (1409) declared that both rivals were illegitimate and declared elected a third purported pope. The schism was finally resolved when the Pisan claimant John XXIII called the Council of Constance (1414–1418). The Council arranged the abdication of both the Roman pope Gregory XII and the Pisan antipope John XXIII, excommunicated the Avignon antipope Benedict XIII, and elected Martin V as the new pope reigning from Rome.