In the summer of 1943, the U.S. began the Gilbert and Marshall Islands campaign to retake the Gilbert and Marshall Islands. After this success, the Americans went on to the Mariana and Palau Islands in summer 1944. Following their defeat at the Battle of Saipan, the Imperial Japanese Navy's Combined Fleet, with 5 aircraft carriers, sortied to attack the Navy's Fifth Fleet during the Battle of the Philippine Sea, which was the largest aircraft carrier battle in history. The battle was so one-sided that it became known as the "Marianas turkey shoot"; the U.S. lost 130 aircraft and no ships while the Japanese lost 411 planes and 3 carriers. Following victory in the Marianas, the U.S. began the reconquest of the Philippines at Leyte in October 1944. The Japanese fleet sortied to attack the invasion fleet, resulting in the four-day Battle of Leyte Gulf, one of the largest naval battles in history. The first kamikaze missions were flown during the battle, sinking and damaging several other U.S. ships; these attacks were the most effective anti-ship weapon of the war.