Excerpts from Books and Wikipedia
"Jerusalem, taken by Saladin in 1187, was returned to Christian control by the emperor Frederick II in 1229 by negotiation with al-Kamil, the Ayyubid sultan of Egypt. . . . A few years earlier the Mongols had destroyed the Turkish Khwarizm Shahdom, a province covering much of central Asia and Iran, sending Turkish refugees fleeing west. In June 1244 about 10,000 Khwarizmian horsemen entered the territory of Damascus, plundering their fellow Muslims. Damascus was too strong to take, so the Khwarizmians headed for Jerusalem. . . . On July 11 the Khwarizmians broke into Jerusalem. The small garrison of Knights Templars and Hospitallers held out until the Khwarizmians promised safe conduct to the coast. On August 23, 6,000 Christians left the city for Jaffa but they were attacked on the way. Only 300 reached their destination. Jerusalem was never regained by the Christians." [Furtado: 1001 Days]