US forces returned to the Philippines in a major invasion at Leyte beginning on 20 October 1944. The Imperial Japanese Navy attacked the invasion fleet on 23–26 October in the Battle of Leyte Gulf, the largest naval battle of the war, but were repulsed with heavy losses. In December 1944 an empty Fort Wint was reclaimed "without firing a shot". By early February 1945 much of the Manila area and part of Bataan had been secured. Corregidor was the biggest obstacle to reopening Manila Bay to shipping. A risky operation to recapture the island via near-simultaneous airborne and amphibious assault was devised. The invasion was set for 16 February and was preceded by air and naval bombardment. The airborne assault was to take place on Topside, the high ground in the west of the island. Only two small drop zones, the parade ground and the former golf course, were available. The overall plan was for the first airborne assault at 0830, the amphibious landing at 1030, and a second airborne lift at 1215. The airborne force was the 503rd Parachute Regimental Combat Team of Lieutenant Colonel George M. Jones, with a parachute field artillery battalion included. The amphibious assault was by the reinforced 3rd Battalion, 34th Infantry Regiment of the 24th Infantry Division.