Imperial Japanese Navy in World War II

During World War II, at the beginning of the Pacific War in December 1941, the Imperial Japanese Navy (IJN) was the third most powerful navy in the world,^[3] and Japan's naval air service was one of the most potent air forces in the world. During the first six months of the war, the IJN enjoyed spectacular success, inflicting heavy defeats on Allied forces while remaining undefeated in battle.^[4] The attack on Pearl Harbor crippled the battleship arm of the US Pacific Fleet,^[5] while Allied navies were devastated during Japan's conquest of Southeast Asia.^[6] Land-based IJN aircraft were also responsible for the sinkings of HMS Prince of Wales and HMS Repulse, the first time in history that capital ships were sunk by aerial attack while underway.^[7] In April 1942, the Indian Ocean raid drove the Royal Navy from South East Asia.^[8] After these successes, the Japanese concentrated on the elimination and neutralization of strategic points from which the Allies could launch counteroffensives against Japan's conquests.^[6] However, at Coral Sea the Japanese were forced to abandon their attempts to isolate Australia,^[6] while the defeat at Midway forced them onto the defensive. The campaign in the Solomon Islands, during which the Japanese lost a months-long battle of attrition, was a decisive defeat for the IJN; they had failed to commit sufficient forces in time to overcome the growing Allied strength in the Solomons.^[9]

During 1943 the Allies were able to significantly reorganize and expand their forces, and American industrial strength began to turn the tide of the war.^[10] The United States ultimately managed to gain the upper hand through a vastly greater industrial output and a modernization of its air and naval forces, while the Japanese wartime economy and military-technological innovation stagnated.^[10] In 1943, the Japanese turned their attention to maintaining a defensive perimeter around their previous conquests. Land-based troops and aircraft on Japanese-held islands in Micronesia were tasked with absorbing and wear down an expected American counteroffensive.^[10] However, American industrial power proved impossible for the Japanese to overcome; the Allied military forces that faced the Japanese in 1943 were so overwhelming in firepower and equipment^[10] that from the end of 1943 to 1944 Japan's defensive perimeter began to buckle, and finally collapsed.^[10] In June 1944, Japanese naval airpower was effectively annihilated during at the Philippine Sea, with American pilots terming it the "Great Marianas Turkey Shoot,"^[11] while the battle of Leyte Gulf in October 1944 destroyed a large part of the IJN's surface fleet.^[12] Consequently, the Japanese lost control of the Western Pacific and access to the oil fields of Southeast Asia, upon which the IJN was reliant for continued operations at sea. During the final phase of the war, the Japanese resorted to a series of desperate measures, including a variety of suicidal attacks popularly known as kamikaze.^[13] By May 1945, most of the Imperial Japanese Navy had been sunk, and the remnants had taken refuge in harbors on the Japanese Home Islands.^[12] By July 1945, all but one of the IJN's capital ships had been sunk in raids by the United States Navy. By the end of the war, the IJN had lost 334 warships and 300,386 officers and men.^[12]