Battle of Muret  At the Battle of Muret on 12 September 1213 the Crusader army of Simon IV de Montfort defeated the joined forces of Raymond VI and 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 and incidentally to join the Languedoc to the crown of France. 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 de Montfort's conquests in Languedoc (which de Montfort pledged to the crown of France). 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 Toulousian 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 militia to assault the walls of the city. Simon de Montfort led an army of 1,000–1,700 French Crusaders, including a small contingent of knights brought by his ally, the Viscount of Corbeil. Montfort had 900 cavalry, of which 260 were knights. His 300–700 infantry stayed behind at Muret to hold the town and tie down the Toulousain militia. Peter of Aragon had brought 800 to 1,000 Aragonese cavalry, joined by a militia of 2,000–4,000 infantry from Toulouse and cavalry from the counts of Comminges and Foix. Peter's combined forces possibly numbered 2,000 cavalry and 2,000–4,000 infantry. Montfort led his knights and horse sergeants out of the walled town and divided his cavalry army into three lines, with his half-brother William of Barres commanding the first line and Montfort himself commanding the third for purposes of tactical command and control. King Peter had arranged his men in the same formation, with the Count of Foix commanding the first line and the King disguising himself in a borrowed suit of armor in the second line. Once deployed, Peter's army remained stationary and waited for the Crusaders' approach. Crossing a stream, William of Barres' cavalry rode for the center of the Count of Foix's line, with the second Crusader line following him. The coalition's first line was crushed by the impetus of the charge and the Crusaders broke through to the second.