The Albigensian Crusade

Unlike the crusades fought against Islam in the eastern Mediterranean, the Albigensian Crusade was directed at fellow Christians within Western Europe, the Cathars of Languedoc, whose dualist teaching that the material world was the creation of an evil power stood outside Catholic doctrine on creation and the incarnation. Papal legates had preached and debated against Cathar belief in the region for decades without dislodging it, in part because local nobility, including Raymond VI of Toulouse, tolerated or protected Cathar communities within their lands.

The murder of the papal legate Pierre de Castelnau in January 1208, for which Innocent III held Raymond VI responsible, gave the papacy grounds to call a crusade rather than continue preaching. Innocent offered the same indulgence granted to crusaders in the East to anyone who took up arms against the Cathars and their protectors, and a largely northern French army, along with contingents from elsewhere, assembled in 1209 under the nominal leadership of the papal legate Arnaud Amalric. Cathar teaching held that a good, spiritual God stood apart from an evil creator responsible for the material world, and that the perfecti, an ascetic elite within the movement, alone underwent the consolamentum that freed a soul from the cycle of rebirth into matter; ordinary believers, the credentes, were not required to live by the same austerity until near death.

The crusader army's first target, Beziers, was stormed on 22 July 1209. The city held both Cathars and Catholics, and the massacre that followed killed a large part of the population regardless; Arnaud Amalric is credited, in a later and disputed account, with telling the crusaders to kill them all and let God sort out his own, a line historians treat as a later embellishment of the massacre's brutality rather than a verified order. Simon de Montfort, who took over the crusade's military command later in 1209, led it through two decades of campaigning marked by further sieges, mass burnings of captured Cathars including at Minerve and Lavaur, and his own death at the siege of Toulouse in 1218.

Fighting continued at reduced intensity after Simon's death until the French crown itself took over the campaign in the 1220s. The Treaty of Paris in 1229 ended the military phase, transferring most of the county of Toulouse to direct French royal control and marrying its heiress to the king's brother. Cathar belief survived the treaty in scattered rural communities, and rooting it out afterward became the task of a newly organized inquisitorial apparatus, licensed by the papacy in the years that followed, rather than of further armed campaigns.