The Japanese war plan, known as the Gradual Attrition Strategy, was developed during the 1930s to meet the US Pacific Fleet battleships if they moved across the Pacific Ocean toward Japan.  Cruisers, destroyers, and submarines would attack first with torpedoes and gunfire to weaken and reduce the Pacific Fleet. The Japanese Combined Fleet, centered on battleships, then would confront the reduced Pacific Fleet in the western Pacific. In a massive night battle the Combined Fleet would destroy the Pacific Fleet. Carrier operations would be added to protect the surface forces.


Isoroku Yamamoto was one of the few naval officers in the 1920s in any country to realize the potential power of carrier-based aircraft. In 1924, while still a captain, he learned to fly and changed his specialty to aviation. This led to his command of the carrier Akagi and, as a rear admiral, command of the First Carrier Division. As an admiral he took command of the Combined Fleet, the combat force of the Imperial Japanese Navy. He wanted more aircraft carriers and opposed the construction of the seventy-four-thousand-ton super-battleships Yamato and Musashi, but the Japanese “gun club” of senior battleship admirals had their way and those ships were built.


Yamamoto had completed two tours of duty in the United States. He was considered, both in Japan and the United States, as intelligent, capable, aggressive, and dangerous. Like most powerful leaders he was articulate and persuasive, and once in a position of power he pushed his agenda relentlessly. He played bridge and chess better than most good players, and, motivated by his skill as a poker player and casino gambler, he was continually calculating odds on an endless variety of options. It remained to be seen whether he would play his odds successfully on the Pacific Ocean chessboard.


Yamamoto saw two serious problems with the Gradual Attrition Strategy. The first was that it did not force action. It depended on the Americans to initiate action at a time of their choosing. That time could be when the United States, with its huge industrial capability, had waited until it built an overwhelming force that could defeat the Japanese fleet even after it had suffered losses brought about by the Gradual Attrition Strategy. Second, the leading naval powers of the world were developing aircraft carriers, and carrier planes could strike at much greater range than cruisers and destroyers. Striking at greater range meant that enemy carrier planes could sink cruisers and destroyers employed in the Gradual Attrition Strategy before they got within range to use their guns and torpedoes. That, in turn, meant that Japan would have to deploy its own carriers to protect its cruisers and destroyers from enemy carrier attack, and that would lead to a different confrontation – carriers versus carriers.


Was it, therefore, not better to go on the offensive and destroy an enemy fleet before it could do the same to one’s own fleet? As a result, Yamamoto superseded the Gradual Attrition Strategy with a new concept built around large, fast-moving carriers. This was an aggressive force that could destroy the US Pacific Fleet without waiting for that fleet to move across the Pacific Ocean. What Yamamoto created was a naval blitzkrieg, a lightning war at sea. As the German army in 1939 and 1940 had employed fast-moving tanks and other mechanized vehicles, supported by Stuka dive-bombers and other aircraft to deadly effect, fast carriers with dive-bombers and torpedo planes were the naval equivalent.


To have a lightning war at sea, the Japanese developed planes and carrier operations that were the most advanced of any navy. The fast, highly maneuverable Zero fighters and the long-range torpedo planes, nicknamed Kate by Pacific Fleet fliers, were the most advanced in any navy. The best US attack plane was the Dauntless dive-bomber, and the Japanese equivalent, nicknamed Val, achieved greater range with lighter bombs. The torpedoes, using pure oxygen in propulsion, were fast and deadly. The Japanese carrier pilots and deck crews were trained to a peak level of expertise. Carrier commanders perfected their operations to allow full deck loads of planes to be launched in a matter of minutes. Yamamoto initiated tactical operations for coordinated launches, formations, and attacks by multiple carriers, a skill the U.S. Navy would not match for several years. By the end of 1941, the First Carrier Striking Force would consist of six carriers: three carrier divisions, each division with two carriers, and was the most powerful naval force in the world.