sentences:  The Mongols invaded Syria several times between 1281 and 1312, sometimes in attempts at joint operations with the Franks, but the considerable logistical difficulties involved meant that forces would arrive months apart, never able to coordinate activities in any effective way.The Mongol Empire eventually dissolved into civil war, and the Egyptian Mamluks successfully recaptured all of Palestine and Syria from the Crusaders.After the Fall of Acre in 1291, the remaining Crusaders retreated to the island of Cyprus.