In November 1239, Peter of Brittany (a leader of the Barons' Crusade) attacked a caravan moving up the Jordan to Damascus. An-Nasir was incensed, and marched on Jerusalem, which was almost undefended. He occupied the city, and the garrison of the citadel surrendered on 7 December. An-Nasir did not attempt to hold Jerusalem, however, but merely destroyed the fortifications and withdrew to Kerak.