Imperial Japanese Navy in World War II

[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 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.

[14] Japanese planners believed that this great maritime clash would be determined by battleships armed with large-caliber guns, a conviction shared by American naval leaders as well.

[17] For this reason, he scrapped the passive strategy of creating conditions for a decisive battle in the western Pacific in favor of a preliminary strike so crippling that it would undermine the American will to fight a lengthy war.

[18] The Japanese strategy for the coming conflict would be to fight a limited war, in which Japan would seize key objectives and then create a defensive perimeter to defeat Allied counterattacks.

The First Operational Phase was further divided into three separate parts; during these, the major objectives of the Philippines, British Malaya, Borneo, Burma, Rabaul, and the Dutch East Indies would be occupied.

The Second Operational Phase would entail further expansion into the South Pacific by seizing eastern New Guinea, New Britain, the Fiji Islands, Samoa, and strategic points in the Australian area.

[5] The Japanese operations to conquer Southeast Asia and establish to a defensive perimeter could proceed without interference, and the U.S. Navy was unable to launch a major trans-Pacific counteroffensive for two years.

[5] However, the two American carriers were at sea at the time of the attack and Pearl Harbor's oil storage, dry dock, submarine piers and maintenance facilities were left unscathed.

[26] The ease with which the Japanese accomplished their initial objectives led to the severe underestimation of the enemy and the resultant failure to concentrate the IJN's superior forces at key places and times.

The Naval General Staff advocated an advance to the south to seize parts of Australia, however, the Imperial Japanese Army declined to contribute the forces necessary for such an operation,[27] which quickly led to the abandonment of the concept.

[28] With only Marcus Island and a line of converted trawlers patrolling the vast waters that separate Wake and Kamchatka, the Japanese east coast was left open to attack.

Concurrently with the attack on Midway, an important aspect of the scheme was Operation AL, the plan to seize two islands in the Aleutians to deny American forces the use of bases close to Japan.

To support this effort, the Combined Fleet stepped up night runs by destroyers and high-speed seaplane carriers (which carried the soldiers' heavy equipment) to Guadalcanal, and a transport convoy was assembled.

Finding the Japanese force just before dawn, two SBDs dive-bombers from the Enterprise attacked Zuihō and scored a pair of hits that damaged the flight deck, starting numerous fires on board the carrier.

The air offensive was codenamed Operation I-Go, consisting of four major attacks conducted on Allied positions on Guadalcanal, Buna, Port Moresby and Milne Bay on April 7, 11, 12 and 14, respectively.

[53] Adding to their predicament was the increasing Allied strength in the region, demonstrated when the Second Fleet arrived at Rabaul on November 5 with six heavy cruisers to engage American naval forces off Bougainville; they were immediately subjected to an attack by carrier aircraft.

Although the Combined Fleet had moved its major vessels out in time to avoid being caught at anchor in the atoll, two days of air attacks resulted in significant losses to Japanese aircraft and merchant shipping.

The Americans destroyed 90% of that airpower in two days, leaving the Japanese with only enough aircrew to form an air group for one light carrier, returning home with 35 of about 450 aircraft with which the Mobile Fleet had begun the battle.

The Japanese were left with two choices: either commit their remaining strength in an all-out offensive, or sit by while the Americans occupied the Philippines and cut the sea lanes between Japan and vital resources from the Dutch East Indies and Malaya.

The plan devised by the IJN was a final attempt to create a decisive battle using its last remaining strength, the firepower of its heavy cruisers and battleships, which were to be all committed against the American beachhead at Leyte.

On the night of October 24–25, the Southern Force, consisting of the two Fusō-class battleships escorted by a heavy cruiser and four destroyers, attempted to enter Leyte Gulf from the south through Surigao Strait.

[64] A force, called Ten-Go, consisting of the battleship Yamato, the light cruiser Yahagi and eight destroyers; Isokaze, Hamakaze, Yukikaze, Asashimo, Kasumi, Hatsushimo, Fuyutsuki and Suzutsuki, was assembled.

The IJN also attempted to build a number of fleet carriers called the Unryū-class, mostly based on the older Hiryū design rather than the newer Shōkaku or Taihō for the sake of reducing construction cost and time.

In the early war years, their advantages were exploited against the often second rate and poorly coordinated Allied ships stationed in the region such as at the IJN victory in the Battle of the Java Sea.

[nb 7] The Navy also had a competent land-based tactical bombing force based around the Mitsubishi G3M and G4M bombers, which astonished the world by being the first planes to sink enemy capital ships underway, claiming battleship Prince of Wales and the battlecruiser Repulse.

[78] A plane from one such long-range fleet submarine, I-25, conducted the only aerial bombing attack on the continental United States when Warrant Flying Officer Nobuo Fujita attempted to start massive forest fires in the Pacific Northwest outside the town of Brookings, Oregon on September 9, 1942.

[83] At the end of World War II, numerous Special Attack Units (Japanese: 特別攻撃隊, tokubetsu kōgeki tai, also abbreviated to 特攻隊, tokkōtai) were developed for suicide missions, in a desperate move to compensate for the annihilation of the main fleet.

[87] A considerable number of Special Attack Units were built and stored in coastal hideouts for the desperate defense of the Home islands, with the potential to destroy or damage thousands of enemy warships.