In 1136 Fulk began building castles around the fortress city of Ascalon. This was to prevent raids on Jerusalem by the Egyptian Fatimids. He also built a castle at Beth Gibelin and placed it in the care of the Knights Hospitaller. Also in 1136 the Grand Master (leader) of the Knights Templar, Hugues de Payens, died. Fulk used his influence with the Templars to get one of his own Angevins, Robert of Craon, elected Grand Master. In 1137 Fulk was besieged at Montferrand. The Patriarch of Jerusalem marched an army to relieve the fortress. But Fulk did not know his own army was coming to his rescue. The Seljuks knew of this and quickly offered Fulk favorable terms. King Fulk surrendered the castle in exchange for his own freedom.