Complex sentence: On August 25 the Crusader rearguard was crossing a defile when it was almost cut off, however, the Crusaders closed up so speedily that the Muslim soldiery was forced to flee.
Split into simpler sentences: On August 25 the Crusader rearguard was crossing a defile when it was almost cut off. However, the Crusaders closed up so speedily that the Muslim soldiery was forced to flee.