sentences:  The oldest documents mentioning it date to the 13th century, when it figured in the Albigensian Crusade; its Cathar castellan was Bernard de Casnac.Simon de Montfort took the castle and installed a garrison; when it was retaken by Bernard, he hanged them all.During the Hundred Years' War, the castellans of Castelnaud owed their allegiance to the Plantagenets, the sieurs de Beynac across the river, to the king of France.