12 September – On this day

At the Battle of Muret was fought on this day in 1213, by the Crusader army of Simon IV de Montfort who defeated the Catharist, Aragonese and Catalan forces of Peter II of Aragon, at Muret near Toulouse.

Simon IV de Montfort was the leader of the Albigensian Crusade to destroy the Cathar heresy. He invaded Toulouse and exiled its count, Raymond VI. Count Raymond sought assistance from his brother-in-law, King Peter II of Aragon, who felt threatened by Montfort’s conquests in Languedoc. He decided to cross the Pyrenees and deal with Montfort at Muret.

On 10 September, Peter’s army arrived at Muret, and was joined by a Toulousain militia. He chose to position his army so their right flank was protected by the Saudrune River, and the left protected by a marsh. He left the Toulousain militia to assault the walls of the city.

Montfort divided his army into three squadrons, and then led them across the Garonne to meet the Aragonese forces. Peter’s ally and brother-in-law, Count Raymond, advised a defensive posture in order to weaken the advancing enemy with bowshot and javelins. Peter rejected this and rode to the front line, forsaking his royal armour for the plain armour of a common soldier. When Montfort’s first squadron charged the field, the Aragonese cavalry was crushed and Peter himself was unhorsed. He cried out, “I am the king!” but was killed regardless. With the realization that their king had been killed, the Aragonese forces broke in panic and fled, pursued by Montfort’s Crusaders.