The castle of Peyrepertuse was the largest Cathar stronghold and one of the last to fall, holding out until 1240.
The contact of Christianity with the Oriental mind and Oriental religions had produced several sects (Gnostics, Manichæans, Paulicians, Bogomilae) whose doctrines were akin to the tenets of the Albigenses. But the historical connection between the new heretics and their predecessors cannot be clearly traced. In France, where they were probably introduced by a woman from Italy, the Neo-Manichæan doctrines were secretly diffused for several years before they appeared, almost simultaneously, near Toulouse and at the Synod of Orléans (1022). Those who proposed them were even made to suffer the extreme penalty of death. The Council of Arras (1025), Charroux, Dep. of Vienne (c. 1028), and of Reims (1049) had to deal with the heresy. At that of Beauvais (1114) the case of Neo-Manichæans in the Diocese of Soissons was brought up, but was referred to the council shortly to be held in the latter city. Petrobrusianism now familiarized the South with some of the tenets of the Albigenses. Its condemnation by the Council of Toulouse (1119) did not prevent the evil from spreading. Pope Eugene III (1145-53) sent a legate, Cardinal Alberic of Ostia, to Languedoc (1145), and St. Bernard seconded the legate's efforts. But their preaching produced no lasting effect. The Council of Reims (1148) excommunicated the protectors "of the heretics of Gascony and Provence." That of Tours (1163) decreed that the Albigenses should be imprisoned and their property confiscated. A religious disputation was held (1165) at Lombez, with the usual unsatisfactory result of such conferences.
Two years later, the Albigenses held a general council at Toulouse, their chief centre of activity. The Cardinal-Legate Peter made another attempt at peaceful settlement (1178), but he was received with derision. The Third General Council of the Lateran (1179) renewed the previous severe measures and issued a summons to use force against the heretics, who were plundering and devastating Albi, Toulouse, and the vicinity. At the death (1194) of the Catholic Count of Toulouse, Raymond V, his succession fell to Raymond VI (1194-1222) who favoured the heresy.
With the accession of Innocent III (1198) the work of conversion and repression was taken up vigorously. In 1205-6 three events augured well for the success of the efforts made in that direction. Raymond VI, in face of the threatening military operations urged by Innocent against him, promised under oath to banish the dissidents from his dominions. The monk Fulco of Marseilles, formerly a troubadour, now became Archbishop of Toulouse (1205-31). Two Spaniards, Diego, Bishop of Osma and his companion, Dominic Guzman (St. Dominic), returning from Rome, visited the papal legates at Montpellier. By their advice, the excessive outward splendour of Catholic preachers, which offended the heretics, was replaced by apostolical austerity. Religious disputations were renewed. St. Dominic, perceiving the great advantages derived by his opponents from the cooperation of women, founded (1206) at Pouille near Carcassonne a religious congregation for women, whose object was the education of the poorer girls of the nobility. Not long after this he laid the foundation of the Dominican Order. Innocent III, in view of the immense spread of the heresy, which infected over 1000 cities or towns, called (1207) upon the King of France, as Suzerain of the County of Toulouse, to use force. He renewed his appeal on receiving news of the assassination of his legate, Peter of Castelnau, a Cistercian monk (1208), which judging by appearances, he attributed to Raymond VI. Numerous barons of northern France, Germany, and Belgium joined the crusade, and papal legates were put at the head of the expedition, Arnold, Abbot of Citeaux, and two bishops. Raymond VI, still under the ban of excommunication pronounced against him by Peter of Castelnau, now offered to submit, was reconciled with the Church, and took the field against his former friends. Roger, Viscount of Béziers, was first attacked, and his principal fortresses, Béziers and Carcassonne, were taken (1209).
The monstrous words: "Slay all; God will know His own," alleged to have been uttered at the capture of Béziers, by the papal legate, were never pronounced (Tamizey de Larroque, "Rev. des quest. hist." 1866, I, 168-91). Simon of Monfort, Earl of Leicester, was given control of the conquered territory and became the military leader of the crusade. At the Council of Avignon (1209) Raymond VI was again excommunicated for not fulfilling the conditions of ecclesiastical reconciliation. He went in person to Rome, and the Pope ordered an investigation. After fruitless attempts in the Council of Arles (1211) at an agreement between the papal legates and the Count of Toulouse, the latter left the council and prepared to resist. He was declared an enemy of the Church and his possessions were forfeited to whoever would conquer them. Lavaur, Dep. of Tarn, fell in 1211, amid dreadful carnage, into the hands of the crusaders. The latter, exasperated by the reported massacre of 6,000 of their followers, spared neither age nor sex. The crusade now degenerated into a war of conquest, and Innocent III, in spite of his efforts, was powerless to bring the undertaking back to its original purpose. Peter of Aragon, Raymond's brother-in-law, interposed to obtain his forgiveness, but without success. He then took up arms to defend him. The troops of Peter and of Simon of Montfort met at Muret (1213). Peter was defeated and killed. The allies of the fallen king were now so weakened that they offered to submit. The Pope sent as his representative the Cardinal-Deacon Peter of Santa Maria in Aquiro, who carried out only part of his instructions, receiving indeed Raymond, the inhabitants of Toulouse, and others back into the Church, but furthering at the same time Simon's plans of conquest.
This commander continued the war and was appointed by the Council of Montpellier (1215) lord over all the acquired territory. The Pope, informed that it was the only effectual means of crushing the heresy, approved the choice. At the death of Simon (1218), his son Amalric inherited his rights and continued the war with but little success. The territory was ultimately ceded almost entirely by both Amalric and Raymond VII to the King of France, while the Council of Toulouse (1229) entrusted the Inquisition, which soon passed into the hands of the Dominicans (1233), with the repression of Albigensianism. St. Dominic’s experiences in the Languedoc inspired his foundation of a new order of well-educated friars to combat heresy and spread the word of God. The first Dominican convent was established in 1215 at Toulouse, the seat of the Albigensian heresy, a year before the pope officially confirmed the order.
The losers were not only the Albigensians, but the entire Languedoc, which had been devastated and impoverished by the protracted conflict. When the final revolts had been suppressed, the once prosperous and flourishing Provenyal culture lay in ruins. The heresy had not disappeared either (the last Cathar outpost fell in 1255), but after 1231 the suppression was entrusted to a new papal institution: the Inquisition. Most of those it tried recanted and did penance in return for their freedom, but a few were burned at the stake. The last Cathar burning was in 1321, and the Albigensians had probably ceased to exist as a sect by the end of the fourteenth century.