Albigensian Crusade Military System

Timeline

1. 1209–1211Carcassonne–Béziers line · LanguedocThe pope granted crusade status for the war against heresy, and northern lords answered the call; the 1209 massacre of Béziers and the siege of Carcassonne demonstrated the system's typical pattern of expansion driven by terror sieges and feudal rewards, with Simon de Montfort becoming the de facto military leader.
2. 1211–1220Toulouse and Beaucaire · ToulouseThe crusade system continuously besieged Toulouse and other major southern towns; the 1216 siege of Beaucaire and the 1217–1218 defense of Toulouse wore down the northern armies, and Simon de Montfort was killed in 1218; Raymond VI of Toulouse and local coalitions used castle networks and citizen militias to delay the conquest, and the campaign entered a long stalemate.
3. 1220–1229All of Languedoc · LanguedocIn the 1220s the French crown gradually took over crusade command, and Louis VIII marched south in person; Toulouse fell in 1226, and the 1229 Treaty of Paris confirmed the incorporation of southern territories into the royal domain, as the Albigensian Crusade military system became a French royal war of conquest and promoted the entrenchment of inquisitorial mechanisms locally.