During his tenure the new Mamluk Sultan, Qalawun, easily conquered in 1289 the County of Tripoli, which had ignored Beaujeu's warnings. In 1290 Qalawun marched on Acre, the capital of the remnant of the Kingdom of Jerusalem, but died in November before launching the attack. His son Al-Ashraf Khalil, however, decided to continue the campaign. Beaujeu led the defence of the city.[citation needed]