Fixation on fleet theory

 How did Navy leaders predict battles between Japan and the United States would turn out? And, how did they intend to fight the war? Before the advent of naval aircraft, most navies in the world believed in a big fleet battle theory, which held that the winner of a battle would be decided by a fight between battleships mounted with large-caliber guns. Japan was no exception, and, before the start of the Pacific War, Japan’s Navy developed a scenario of intercepting and engaging a U.S. fleet sailing from the U.S. mainland around Mariana Islands in the Central Pacific.

 In the Pearl Harbor attack, however, Japan succeeded in destroying most of the U.S. Pacific Fleet’s battleships with 350 naval aircraft launched from Japanese carriers. Also, in run-up to the Battle of Malaya that took place immediately after the Pearl Harbor attack, land-based naval aircraft sank two state-of-the-art British battleships. In both cases, most damage was achieved by attack planes rather than by ships’ guns. In fact, during these two battles Japan put into practice the air superiority theory, which held that naval aviation was the primary instrument for delivering combat power to destroy battleships which were the center of naval power. Commander-in-Chief of the Combined Fleet Yamamoto was one of those who consistently supported the air superiority theory.

 In the Pearl Harbor and Malaya operations, battleship units—the main force of the big fleet battle theory—did not have any chance to join in the offensive. The Japanese tactic used in both battles was a breakthrough Japanese achievement in global naval strategy.

 Despite these successful operations, however, neither the Naval General Staff nor the Combined Fleet replaced the big fleet battle theory with the air superiority theory. The Combined Fleet continued to maintain the same modus operandi with an emphasis on battleships. The design of the Shinano, the third Yamato-class battleship, was not changed to make it an aircraft carrier. There were no steps taken to swiftly increase the production of aircraft carriers and airplanes.

 In the Battle of Midway, the formation of the Combined Fleet was as follows: The First Carrier Strike Force—consisting of the Akagi and three other aircraft carriers and led by Commander-in-Chief Nagumo—was positioned at the vanguard, followed 500 kilometers to the rear by the core naval force. The main assault force consisted of the flagship Yamato, carrying Commander-in-Chief of the Combined Fleet Yamamoto, and six other battleships, three cruisers and 21 destroyers. The plan was to give full support to the strike force with the main unit in the rear.

 Postwar recollections by Shigeru Fukutome, chief of the Operations Bureau of the Naval General Staff, reflected the mind-set of the Navy at that time: “We believed the battleships were still the primary force, with aircraft carrier units being effective naval power to aid the main force. We were waiting for a chance to capture Midway Island so that the Combined Fleet’s core force would be able to shorten the distance and intercept the enemy’s main force.”

 The operation plan worked out by the Combined Fleet for the war with Britain, the Netherlands and the United States, contained gallant expressions, such as “smash the U.S. fleet” and “intercept and annihilate the enemy forces.”The plan, which was approved by the Navy on November 5, 1941, reflected the big fleet battle theory Japan had adopted since the Japanese fleet destroyed battleships from Russia’s Baltic Sea Fleet in the May 1905 Battle of the Sea of Japan, the decisive encounter of the Russo-Japanese War.

 In the Pearl Harbor attack and the Battle of Malaya, airplanes became the key players in naval operations, replacing battleships. Although the Navy demonstrated this point to observers in Japan and abroad, it was not able to shed the traditional big fleet battle theory, partly because its leadership was comprised of gunnery or torpedo experts. There were only a small number of aviation experts among Japanese naval leaders.

 Rear Admiral Takijiro Onishi, Chief of Staff of the Eleventh Air Fleet, visited Matome Ugaki, Chief of Staff of the Combined Fleet, in spring 1942 and asserted that “the core of armament was in aviation.”Ugaki, whose expertise was in battleship gunnery and who was a follower of the big fleet battle theory, insisted, however, “It is difficult to use air force in the vast ocean. Aircraft carriers alone can only fulfill the task of moving air power forward.” With this belief, Ugaki prepared the Combined Fleet for the Battle of Midway.

 During the Battle of Midway, the main units—positioned about 10 hours away at full speed from the strike force—were not able to shorten the distance to the enemy fleet in the face of a speedy air attack launched by the U.S. Fleet on the Japanese carrier strike force. Japan’s main force did not have the chance to fire a single shot and sat helpless in preventing four aircraft carriers from being destroyed. If the Japanese aircraft carriers had been escorted by battleships and cruisers, like U.S. aircraft carriers were, the Japanese fleet might have responded to U.S. air attacks in a totally different way.