For 40 years, the Catholic Church had three men simultaneously claiming to be the one true Pope — each excommunicating the others as frauds.
The Western Schism erupted in 1378 when cardinals who had just elected Urban VI declared his election invalid, claiming the Roman mob had terrified them into choosing him. They then elected a second pope, Clement VII, who set up a rival court in Avignon, France — and both men immediately excommunicated each other.
The crisis deepened at the Council of Pisa in 1409, which tried to solve the problem by deposing both popes and electing a new one. The plan backfired spectacularly: neither existing pope accepted their deposition, leaving the Church with three simultaneous claimants to St. Peter's throne.
The schism was as much political as religious. France, Scotland, and Castile backed the Avignon pope, while England, the Holy Roman Empire, and most of Italy supported Rome. Europe's great powers used papal allegiance as a tool of international rivalry.
The Council of Constance (1414–1418) finally broke the deadlock by demanding all three popes step aside. The Roman pope Gregory XII agreed to resign voluntarily; the Pisan pope John XXIII fled in disguise but was captured and deposed; the Avignon holdout Benedict XIII refused to the end, dying in exile still insisting he was the rightful pope.
The Council of Constance also burned the Czech reformer Jan Hus at the stake in 1415, despite granting him safe conduct. The act illustrated how the schism-weakened Church felt compelled to crush any challenge to its authority while it struggled to reunify.
The schism gave powerful momentum to Conciliarism — the theory that a Church council outranked the pope. This idea threatened the entire medieval papal hierarchy and would resurface repeatedly, feeding the intellectual climate that eventually produced the Protestant Reformation a century later.
When Pope Martin V was finally elected in 1417 to reunify the Church, he inherited a fractured institution whose prestige had been shattered by four decades of rival pontiffs calling each other heretics and antichrists. Restoring trust in papal authority would take generations.