Louis's campaign against Egypt did not go well. He successfully captured Damietta, but lost his entire army at the Battle of Al Mansurah, and was himself captured by the Egyptians. His release was eventually negotiated in return for a ransom (some of which was a loan from the Templars) and the surrender of the city of Damietta. A few years later, in 1253 he sought allies among both the Ismaili Assassins and the Mongols. When he saw a letter from Hethum's brother, the Armenian noble Sempad, which spoke well of the Mongols, Louis dispatched the Franciscan William of Rubruck to the Mongol court. But the Mongol leader Möngke replied with only a letter via William in 1254, asking for the King's submission to Mongol authority.