Which pope initiated the Albigensian Crusade?

Pope Innocent III initiated the Albigensian Crusade, launched in 1209 against Catharism in Languedoc, southern France. Unlike the campaigns usually associated with Jerusalem, this crusade targeted a religious movement within western Europe.

Innocent became pope in 1198 and regarded the Cathars, whom Catholic authorities considered heretics, as a serious threat to church authority. His representatives attempted preaching and negotiation in Languedoc, but the effort produced little lasting change. The pope increasingly pressed local nobles and the French monarchy to act against Cathar communities and their protectors.

The immediate trigger came after the papal legate Pierre de Castelnau was murdered in 1208. Innocent called for a military expedition and offered participants crusading privileges, including spiritual rewards associated with campaigns in the Holy Land. The first armies entered Languedoc in 1209 and captured Béziers and Carcassonne.

Simon de Montfort later became the crusade’s leading military commander, which is why he is sometimes mistaken for its initiator. The campaign lasted until 1229 and contributed to the expansion of royal French power in the region, while the later Inquisition pursued surviving Cathar communities.