 Rain interrupted the siege , but on 21 March , immediately south of Krak des Chevaliers , <unk> 's forces captured a triangular <unk> possibly defended by a timber palisade . On 29 March , the attackers undermined a tower in the southwest corner causing it to collapse whereupon Baibars ' army attacked through the breach . In the outer ward they encountered the peasants who had sought refuge in the castle . Though the outer ward had fallen , with a handful of the garrison killed in the process , the Crusaders retreated to the more formidable inner ward . After a lull of ten days , the besiegers conveyed a letter to the garrison , supposedly from the Grand Master of the Knights Hospitaller in Tripoli , which granted permission for them to surrender . Although the letter was a forgery , the garrison <unk> and the Sultan spared their lives . The new owners of the castle undertook repairs , focused mainly on the outer ward . The Hospitaller chapel was converted to a mosque and two <unk> were added to the interior . 
