Original: In 1187, Saladin defeated the armies of the Crusades at the Battle of Hattin, largely because he was able to cut the Crusaders off from the valuable fresh water of the Sea of Galilee.
Simplified: In 1187, Saladin defeated the armies of the Crusades at the Battle of Hattin, mainly because he cut the Crusaders off from the valuable fresh water of the Sea of Galilee.