The Albigensian Crusade was a military campaign initiated by the Catholic Church in the early 13th century, specifically from 1209 to 1229. It aimed to eliminate the Cathar heresy in the region of Languedoc, in southern France. The Cathars held beliefs that were contrary to Catholic doctrine, leading to tensions between them and the Church. The crusade involved a series of battles and sieges, resulting in significant loss of life and destruction. Key figures included Simon de Montfort, who played a prominent role in the campaign. Ultimately, the crusade led to the consolidation of royal power in France and the establishment of the Inquisition to combat heresy.