the Mongols at the Battle of Köse Dağ in June 1243, threatening the whole of Mesopotamia. At as-Salih's invitation, the Khwarezmian army advanced through Syria and Palestine and, in the Siege of Jerusalem of 15 July 1244, destroyed the Holy City. The city's citadel, the Tower of David, surrendered on 23 August 1244, and the Christian population of the city was expelled or massacred. Later that year as-Salih, again allied to the Khwarezmians, confronted as-Salih Ismail, now allied with the Crusaders, at Gaza in the Battle of La Forbie, marking the collapse of Christian power in the Holy Land. In 1245, as-Salih captured Damascus, and was awarded the title of sultan by the caliph al-Musta'sim in Baghdad. In 1246, he assessed that his Khwarezmian allies were dangerously uncontrollable, so he turned on them and defeated them near Homs, killing their leaders and dispersing the remnants throughout Syria and Palestine. Three years later when the Crusade began, as-Salih was away fighting his uncle in Syria and quickly returned to Egypt where he died on 22 November 1249. The military orders The treaty of 1243 with the Ayyubids did not keep the peace for long, but the military orders in the kingdom united to fight at Hirbiya in what is sometimes called the Battle of La Forbie, sometimes known as the Battle of Gaza, from 17 to 18 October 1244. Here the Crusaders, led by Walter IV of Brienne, and a Damascene army met the Egyptian and Khwarezmian armies. In what was to be the final major battle between the Franks and Muslims, 5000 Crusaders died and 800 were taken prisoner. Among the dead were Armand de Périgord, Grand Master of the Temple, and Peter II of Sargines, archbishop of Tyre. Taken prisoner were Guillaume de Chateauneuf, Grand Master of the Hospitaller, and the commander Walter IV of Brienne. Only 33 Templars, 27 Hospitallers, and three Teutonic Knights survived, escaping to Ascalon along with Philip of Montfort and Latin patriarch Robert of Nantes. Jean de Ronay, in an acting capacity for the Hospitallers, and Guillaume de Sonnac, Armand's successor, would go on the support the Seventh Crusade. Both arrived in the Holy Land after the 1244 defeats. Hugues de Revel, lord of Krak des Chevaliers from 1243 to 1248, would become de Chateauneuf's permanent successor in 1258. Louis IX of France Louis IX was born on 25 April 1214, the son of