Peter II, King of Aragon, died at the Battle of Muret in 1213 during the Albigensian Crusade. The battle was fought on 12 September near Muret, south of Toulouse, between a smaller crusader army commanded by Simon de Montfort and a larger coalition supporting Raymond VI of Toulouse. Peter intervened because French-backed crusader expansion threatened his influence in Languedoc and affected his relatives and vassals there.
Peter had been crowned in Rome in 1204 and was known by the epithet “the Catholic.” He crossed the Pyrenees to support the Toulouse-led coalition, despite advice to avoid a direct confrontation. Montfort’s cavalry launched a series of attacks that disrupted the allied army. Peter fought in the battle and was killed after becoming separated from the main body of his forces.
His death turned Muret into a major political turning point. Aragonese influence north of the Pyrenees was sharply reduced, while French power in Occitania expanded. Peter’s young son, James, succeeded him and later became known as James the Conqueror. The battle is sometimes described simply as a conflict between France and Aragon, but the armies also included Toulouse and other Occitan allies, making it a central episode in the wider struggle over Cathar Languedoc.