Haruna and Shirane turn destroyers into helicopter command ships

The Haruna class answered the need for embarked ASW aviation after a conventional helicopter carrier proved domestically contentious. Its large flight deck and command role let escort groups operate around a ship with a nominal complement of two helicopters and space for three. The design addressed the same broad ASW aviation problem that produced Britain's Invincible class, while Japan packaged the capability as a large flight-deck destroyer. Shirane and Kurama refined the idea after several years of operating experience. Four aviation command ships meant one could be at sea and another available, strengthening force generation for sea-lane protection.