The outbreak of the Great Western Schism in 1378 was the direct result of the Avignon papacy preceding it for nearly seventy years. From 1309 to 1377, papacy, curia, and eventually the papal archives relocated to the French city of Avignon without hope of a return. When Gregory XI was elected in 1377, he promised to restore the papacy to Rome, which he did for a short time. Before his death, however, Gregory had decided to make his way back to France. The prospect of a French papacy raised tensions both within the city of Rome and amongst the cardinals set to elect Gregory’s replacement. The conclave was split and finally settled on Urban VI in April 1378. He appeased the Roman masses because he was an Italian and the French because he had served in the curia at Avignon. The cardinals soon came to regret their decision due to Urban’s personal volatility and all of them save four Italians fled to Avignon, where they claimed that the original election of Urban came under duress and chose to hold a second conclave where they would elect another pope in July 1378, a French cardinal who assumed the name Clement VII and took up residence in Avignon.
Both Urban and Clement maintained their elections were valid and that they had rightful claims to the papal tiara. The result was a schism that rent Western Europe into two rival “obediences” for nearly fifty years. The Roman line, which included Urban VI (1378–89), Boniface IX (1389–1404), Innocent VI (1404–06), and Gregory XII (1406–15), received the support of most of the Germanic Holy Roman Empire, as well as England, which was engaged in the Hundred Years’ War with France. The shorter Avignonese line was constituted by Clement VII (1378–94) and Benedict XIII (1394–1417), who would contest his later deposition as pope until dying in 1423. France, England’s archrival Scotland, and Spanish Castile all fell in line with the French claimant. The difference between the two lines was stark during this period. Rome lost much of its financial base and curial infrastructure and was thus forced to sell ecclesiastical offices to maintain solvency. Avignon, on the other hand, retained much of the fiscal bequest it had received during the papal residence in France. However, increasing taxation from the French church led to strain on its part as the plague ravaged much of Europe and brought commerce to a halt.
Attempts to unify the papacy were in vain throughout the period. The two popes themselves proposed to resolve it by military force (via facti). The more diplomatic solution of the period was to call for a peaceful decision on the part of the two popes (via compromissi), but neither line would allow that. With no other options, by the end of the fourteenth century there were calls for the rival colleges of cardinals in Rome and Avignon to depose both popes jointly and elect a replacement (via cesionis). However, the option with the greatest theological precedent and the most ecclesiastical support was to convene a general council (via concilii), wherein the gathered bishops would vote to determine the rightful claimaint. This was based on the stipulation in medieval canon law that the church could depose a contumacious pope who refused to recant of his errors. At the Council of Pisa in 1409, several hundred prelates, theologians, and secular rulers gathered and, when neither rival claimant supported the council, they deposed both and elected a new pope, Alexander V (1409–10). Due to Alexander’s unexpected death, the quality of his successor John XXIII’s (1410–15), and the refusal of either Avignon or Roman line to give up his claim, the schism was worsened by increasing to three papal lines. The final resolution of the Great Western Schism would have to await the Council of Constance (1414–1418), which would eventually affirm the Roman line.