Complex sentence: The 11th Airborne Division would not be used as paratroopers; however, they were sent in as light infantry after the Battle of Leyte Gulf to help mop up after the six divisions that had gone ashore earlier.
Split into simpler sentences: The 11th Airborne Division would not be used as paratroopers, however, but as light infantry after the Battle of Leyte Gulf. It helped mop up after the six divisions that had gone ashore earlier.