Complex sentence: Though the Mamluks were the traditional enemies of the Franks, the Barons of Acre recognized the Mongols as the more immediate menace, and so the Crusaders opted for a position of cautious neutrality between the two forces.
Split into simpler sentences: Though the Mamluks were the traditional enemies of the Franks, the Barons of Acre recognized the Mongols as the more immediate menace. Instead of joining one side or the other the Crusaders opted for a position of cautious neutrality between the two forces.