The Cathars were a radical religious sect that had taken root in southern France and by the early thirteenth century a good part of the population of the area were Cathars. The Cathars held radically different beliefs from Christianity and are properly considered a different religion entirely, rather than a perversion of Christianity itself. They believed that there were two worlds the spiritual and the material, only the spiritual was clean of sin while the material world was inherently sinful. In order to escape the inherent sinfulness of their human existence the Cathars underwent a ritual known as the consolamentum. This ritual was a kind of combination Baptism, Penance, and Holy Orders all in one; most did not receive it until they were close to death. It was a ritual purification in which the participant was cleansed of all sin and vowed to follow the moral laws of the Cathars, namely they refrained from sex, had no possessions, did not eat meat, and traveled to preach their religion.
The papacy had been trying to stamp out the heresy since the eleventh century through the use of preachers and by encouraging the secular nobility to eliminate the heresy. This was stepped up in the early 13th century with the recognition of the Dominican order by Pope Innocent III (p.1198-1216) in 1205. Â The order was founded by St. Dominic (1170-1221) as an order of itinerant friars attempting to bring the Cathars back to orthodoxy through their example and preaching. Preaching had limited success because the heretics had the support of many of the nobility who were heretics themselves, or at least sympathetic to them. The most powerful protector of the Cathars were the counts of Toulouse whom the Popes continually urged to combat the spread of the heresy. In 1208 Pope Innocent III, exasperated with the unwillingness of Count Raymond VI of Toulouse (1156-1222) to suppress the Cathars, excommunicated him and placed the county of Toulouse under interdict. Simultaneously with his excommunication of Raymond, the Pope sent letters throughout France preaching Crusade against the Cathars and their supporters.
The call to Crusade was answered enthusiastically by the people of northern France and in 1209; a Crusading army led by Simon de Montfort (1160-1218) attacked and took the towns of Beziers and Carcassonne. At Beziers, the Crusaders massacred the population of the town; reportedly, when the papal legate Arnaud-Amaury was asked how to tell the Cathars from Christians his response was “Kill them all. God will know his ownâ€. The Crusaders had only taken a forty-day vow so as soon as their vow was up they went home which left Simon to hold onto his conquests with only his personal retainers. Over the winter, the Cathars managed to regain most of their lost territory but Simon went back on the offensive in the spring and regained most of the territory lost over the winter.
By 1211, Raymond had turned intransigent, repudiated his penance, and sought help from King Peter II of Aragon (1174-1213). Peter II fresh from his participation at the Spanish Battle of Los Navas de Tolosa sought to use the prestige he had gained in support of Raymond who he took under his protection in 1212. The Pope agreed to hear the arguments of Peter at the Council of Lavaur, which had previously been scheduled, but the agenda was now changed to accommodate the Pope. The Council summarily rejected all Peterâ€™s arguments and claimed that the lands in question were still infected by heresy.
In 1213, Pope Innocent III removed most Crusader indulgences for southern France in anticipation of the Fifth Crusade and Raymond and Peter marched on Simon to drive him from the south. The two armies met at The Battle of Muret on 12 September 1213, where Simon, with a much smaller army was victorious killing King Peter in the process. After Muret, Simon quickly consolidated his conquests and in 1215, his control of Languedoc was confirmed by the council of Trent.
After the removal of the Crusading indulgence Simon was forced to rely on mercenaries to defend his gains against a resurgent Raymond VI and his son Raymond VII. Simon was killed on June 25 1218 at the siege of Toulouse by a stone fired from a mangonel. Simon de Montfortâ€™s son Amalric (1192-1242); attempted to maintain his claim but by 1220 was reduced to the land immediately surrounding Carcassonne.
The cause was taken up by the king of France Louis VII in 1223, who sponsored a council at Bourges in 1225 to settle the matter. The council declared Raymond a heretic, his lands forfeit, and excommunicated him. Louis VII invaded in 1226 and Avignon surrendered on September 9 but the king died in November and the Crusade stalled.
The Albigensian Crusade formally ended on April 29 1229 with the Peace of Paris. The Crusade was a failure in that it did not end the heresy of Catharism, which would continue for another hundred years until finally stamped out by the inquisition. The only real winner in the Crusades was the French monarchy, which gained much more power because the newly conquered lands of southern France were enfiefed to him thus raising the kingâ€™s prestige even further above the rest of the French nobility.
Madden, Thomas, F. ed. The Crusades: An Illustrated History. Ann Arbor, MI: University of Michigan Press. 2004
Madden, Thomas F. The New Concise History of the Crusades. Lanham, MD: Rowman & Littlefield Publishers, Inc. 2005
Riley-Smith, Jonathan, ed. The Oxford Illustrated History of the Crusades. New York, NY: Oxford University Press. 1995
 Madden, Thomas F. The New Concise History of the Crusades. p. 122
 Crusades encyclopedia. “Arnaud Amauryâ€. http://www.crusades-encyclopedia.com/arnaudamaury.html
 Madden, p. 129
 Ibid., p. 135