The Battle of Leyte Gulf, in 1944, was the largest naval encounter in the war. The Imperial Japanese Navy had already had increasingly large losses in battles such as the Battle of Midway and the Philippine Sea, which wiped out their carrier fleets. However, as the Americans targeted Leyte the Japan mobilized much of its navy to defend Leyte, which if occupied would cut off Japanese oil supplies.
The first American troops landed at Leyte Gulf on October 20. This marked the beginning of the Battle of Leyte Gulf. A couple of days later, on October 22, five Japanese fleets departed from Borneo to defend Leyte. The IJN's plan was to lure the Third Fleet northwards with a fleet of depleted aircraft carriers so that the Center Force could strike at U.S. troop transport ships.
On October 23 the Japanese and American fleets first met at the Palawan Passage. The Japanese fleet was effectively ambushed by U.S. submarines. As such, a couple of submarines torpedoed sank the Maya and Atago heavy cruisers.
However, these losses were fairly light in relation to what would follow. As one Japanese fleet made it to the Sibuyan Sea, hundreds of U.S. carrier aircraft bombed it. The sorties sank one Yamato-class battleship, and numerous others were hit.
U.S. aircraft later intercepted the southern Japanese fleet off Surigao Strait. The planes also bombed that feet before the first American task force, which outnumbered the Japanese fleet, intercepted it. During the skirmishes, the Imperial Japanese Navy lost two further battleships, a heavy cruiser and a couple of destroyers.
The U.S. Navy dominated the battle up to October 25. The Japanese had lost a number of battleships, heavy carriers and destroyers. Numerous other ships had come under fire, but somehow remained afloat during the Allied onslaught. The Americans had lost little more than a submarine, which ran aground after the first skirmishes.
However, October 25 was less one-sided as the Imperial Japanese Navy spotted a handful of lightweight U.S. carriers off Samar. Japanese battleships closed in on the American task group and sank two destroyers and an escort carrier. However, about 500 aircraft from the U.S. light carriers aided the Americans and sank three IJN heavy cruisers. Consequently, the Japanese fleet turned away and withdrew from the battle.
The last stages of the Battle of Leyte Gulf emerged off Cape Engano. This involved the remaining Japanese fleet and Halsey’s Third Fleet. Both had their own carriers, so both sides made aircraft sorties. However, the Americans had far more aircraft than the IJN, and their thousands of bombers sank one of the few remaining Japanese fleet carriers. In addition to this, a couple of destroyers were also lost before the IJN pulled out from the battle.
By October 26 the Leyte Gulf battle was all but over as the remaining Japanese ships retreated from Leyte. In the aftermath of Leyte Gulf, the IJN had lost 12 destroyers and eight cruisers. In addition to this, a further three battleships and a fleet carrier along with thousands of supporting personnel. The only consolation was that some of the fleet escaped intact, as 35 destroyers had entered along with 20 cruisers and nine battleships.
The losses at Leyte Gulf were great for Japan, and left them with little to defend the home islands such as Iwo Jima. The IJN would not enter further naval engagements in 1945. As such, there was no naval support available for the defense of islands such as Iwo Jima. The Allies had clear naval superiority after Leyte Gulf.
The Allied navy had lighter losses. Overall, the IJN sank a light carrier and two destroyers during the battle, along with supporting personnel. Although seemingly light in comparison, questions were still raised about the battle.
Most debate pertained to the movement of the Third Fleet northwards away from the Seventh Fleet. By doing so, it was pulled away from supporting the Seventh Fleet against a Japanese fleet. As such, the Americans could have potentially cut their losses. As the historian Morison notes in his book, “The mighty gunfire of the Third Fleet's Battle Line, greater than that of the whole Japanese Navy, was never brought into action."
However, despite this America was still able to secure Leyte. The Sixth Army took the beaches and then secured Leyte at the Battle of Ormac Bay. With Leyte taken, the Philippines soon followed. That cut Japan off from oil supplies among other resources.
Further defeats for Japan would follow in 1945. The Ryukyu islands fell in 1945. With no naval support, Iwo Jima was also captured in 1945.
With the war lost, Japan surrendered unconditionally in September of 1945. The Allies celebrated VJ day and the Pacific War was over.