Controlling the vast reaches of the Pacific was always going to be challenge to warplanners of the Empire of Japan prior to World War 2 (1939-1945). As such, the Imperial Japanese Navy (IJN) invested heavily during the inter-war period on mighty vessels to make the arduous, long journeys required. Part of the service's inventory became a grand fleet of aircraft carriers to help expand the offensive air arm of the Japanese Empire and IJN Kaga was a product of the period.
Kaga began life as one of two planned Tosa-class battleships but the agreed-upon terms of the Washington Naval Treaty of 1922 rewrote this intention and her incomplete hull lay in wait for scrapping. However, the 1923 Great Kanto Earthquake led to the loss of the battlecruiser IJN Amagi - which was itself awaiting conversion to aircraft carrier - so the Kaga was selected to replace her. From the period of 1933 to 1935, the warship was rebuilt to the new standard of fleet carrier. She retained the original battleship-like hull of her preceding design but was given a short "flat top" main flight deck and associated systems and subsystems for her new role. A pair of short "fly off" decks were also added over the forecastle and exhaust ducts for the engines were run along the starboard side of the vessel. Onboard provision allowed for a total of sixty combat aircraft to be carried.
Two years of extensive trials then followed so it was not until November 17th, 1921 that she was launched to sea and not until March 31st, 1927 that her construction was finally finished. Her commissioning occurred on November 30th, 1929. In 1933, she was set aside for modernization which lasted until mid-1935 and among the major improvements to her design was a simplified full-length main flight deck, an increase in combat aircraft carried and a more efficient, conventional island superstructure.
As completed, the vessel displaced 38,815 tons and held a length of 812.5 feet, a beam of 106.7 feet and a draught of 31 feet. Power came from 8 x Kampon Tyep B boilers feeding 4 x Kampon geared steam turbines developing 127,400 horsepower to 4 x Shafts under stern. Speed in ideal conditions could reach 28 knots and endurance was out to 10,000 nautical miles (12,000 miles).
Internally, she was crewed by up to 1,700 personnel. Armor protection included 6" of plate at the belt and up to 1.5" of coverage at the deck. Her air arm consisted of ninety total aircraft (an increase from the original sixty) which was typically a mix of A6M "Zero" fighters, D3A dive bombers and B5N torpedo bombers. Point defense armament was led by 10 x 200mm (7.9") single-gunned Anti-Aircraft (AA) emplacements, 8 x 127mm (5") AA guns in double-gunned mountings and 11 x 25mm AA guns in double-gunned mountings.
IJN Kaga was one of the six aircraft carriers deployed by the IJN during the Attack on Pearl Harbor (December 7th, 1941), a devastating assault on the vital American naval port in the Pacific. From there her career took her to the East Indies where her warplanes continue to ravage foes. Voyages ranged throughout the South Pacific and into the Indian Ocean as the Japanese conquest was made all but certain against unfortunate foes. Her fortunes changed, however, at the Battle of Midway fought from June 4th until June 7th, 1942. There, she took several direct hits from a flight of some 25 American Navy Dauntless SBD dive bombers launched from USS Enterprise. Heavily damaged and on fire, IJN Kaga was abandoned by her owners with 811 Japanese personnel lost in the action taking place on June 4th, 1942.
Beyond Kaga, three other IJN carriers were claimed by the Americans at Midway - marking the attack a critical defeat for the Japanese Navy and depriving the service of ultra-crucial warships, veteran pilots and veteran support crews.