Soryu, Hiryu, and Kido Butai doctrine

Once both carriers entered service, they helped make Kido Butai more than a paper concept. Their range, speed, and air-group capacity allowed the Japanese Navy to test a mobile striking force with ships that could operate together. Early First Air Fleet organization exposed a practical sorting process: Akagi, Kaga, Soryu, and Hiryu formed the useful core, smaller or less suitable ships moved into separate divisions, and Shokaku and Zuikaku later added the mass used at Pearl Harbor. Within interception-attrition operations, fast carrier attacks were supposed to strike, disappear, and pull a stronger opponent toward the battle fleet. American War Plan Orange and British planning could anticipate this approach because Japan's smaller fleet and Pacific geography constrained its strategic choices. Doctrine then changed as exercises and wartime service revealed what the ships and air groups could actually do.