During 1943 the Allies were able to reorganize their forces and American industrial strength began to turn the tide of the war.
American forces ultimately managed to gain the upper hand through a vastly greater industrial output and a modernization of its air and naval forces.
In 1943, the Japanese also turned their attention to the defensive perimeters of their previous conquests.
Forces on Japanese held islands in Micronesia were to absorb and wear down an expected American counteroffensive.
However, American industrial power became apparent and the military forces that faced the Japanese in 1943 were so overwhelming in firepower and equipment, that from the end of 1943 to 1944 Japan's defensive perimeter failed to hold.
Defeat at the Philippine Sea was a disaster for Japanese naval air power with American pilots terming it, the Great Marianas Turkey Shoot, while the battle of Leyte Gulf led to the destruction of a large part of the surface fleet.
Consequently, the Japanese lost control of the Western Pacific.
During the last phase of the war, the Japanese resorted to a series of desperate measures, including a variety of Special Attack Units which were popularly called kamikaze.
By May 1945, most of the Imperial Japanese Navy had been sunk and the remnants had taken refuge in Japan's harbors.
By July 1945, all but one of its capital ships had been sunk in raids by the United States Navy.
At the end of the war, the IJN had lost 334 warships and 300,386 officers and men.