sentences:  Hethum I, king of the Christian nation of Cilician Armenia, had submitted to the Mongols in 1247, and strongly encouraged other monarchs to engage in a Christian-Mongol alliance, but was only able to persuade his son-in-law, Prince Bohemond VI of the Crusader State of Antioch, who submitted in 1260.Other Christian leaders such as the Crusaders of Acre were more mistrustful of the Mongols, perceiving them as the most significant threat in the region.The Barons of Acre therefore engaged in an unusual passive alliance with the Muslim Mamluks, allowing Egyptian forces to advance unopposed through Crusader territory to engage and defeat the Mongols at the pivotal Battle of Ain Jalut in 1260.