 At the time of the crusade, Joinville placed himself in the service of the king and became his counsellor and confidant.In 1250, when the king and his troops were captured by the Mameluks in the Battle of Al Mansurah, Joinville, among the captives, participated in the negotiations and the collection of the ransom.Joinville probably brought himself even closer to the king in the difficult times that followed the failure of the crusade (including the death of his brother Robert, Count of Artois).