Bishop Foulques had tumultuous relations with his diocese, primarily on account of his support of the Albigensian Crusade, which was popularly perceived as a war of aggression against the region. Hated by many Toulousains and by Count Raymond VI of Toulouse he left Toulouse on 2 April 1211, after the crusaders laid siege to Lavaur. Soon afterwards he instructed all clerics to leave the city. He was present at the siege in April–May 1211; he then travelled north to France, where he preached the Crusade alongside Guy of les Vaux-de-Cernay (the abbot of the Vaux-de-Cernay Abbey). He then returned to the south, participating in the Council of Pamiers in November 1212, in the Council of Lavaur in January 1213, in the meeting with Peter II of Aragon on 14 January 1213, at the Battle of Muret on 12 September 1213, and at the Council of Montpellier in January 1215. There he was instructed by the Papal legate, Peter of Benevento, to take possession of the Château Narbonnais, the Count's residence, at Toulouse; thus he finally returned to the city in February 1215.