in 1067 carcassonne became the property of raimond bernard trencavel, viscount of albi and nîmes. carcassonne became famous in its role in the albigensian crusades, when the city was a stronghold of occitan cathars. in august 1209 the crusading army of simon de montfort forced its citizens to surrender. he added to the fortifications. carcassonne became a border citadel between france and aragon.