Kaga

The Vessel

The Imperial Japanese Navy aircraft carrier Kaga was, like her sister Akagi, a converted battleship hull. She had been originally laid down in 1920 as the lead ship of the projected Kaga-class battleships, was cancelled under the Washington Naval Treaty in 1922, and was converted to an aircraft carrier between 1923 and 1928. She was commissioned at the Yokosuka Naval Arsenal on 31 March 1928.

Her conversion produced the largest Imperial Japanese Navy carrier of her generation: 247 metres long, 38,200 tons as completed, and initially fitted with the three-flight-deck configuration. Her 1934-1935 modernisation rebuilt her to single-deck configuration with a 250-metre continuous flight deck, an enclosed island superstructure, and improved propulsion machinery giving her 28 knots. Her air group at the time of her final operations consisted of 63 aircraft (18 fighters, 18 dive bombers, 27 torpedo bombers). She was slower than Akagi but larger, with better internal subdivision and greater aviation fuel capacity.

Her operational service from 1932 forward included fleet aviation exercises in the Inland Sea and off China, and from 1937 onward offensive air operations against Chinese shore targets during the Sino-Japanese War. She participated in every major Kidō Butai operation from Pearl Harbor through May 1942.

The Voyage

On the morning of 4 June 1942 Kaga was operating within the Kidō Butai carrier formation, one of the two "port column" carriers (with Akagi) while Sōryū and Hiryū formed the "starboard column". This formation, typical of Nagumo's four-carrier operations, allowed each column to conduct independent flight operations while mutual defensive air cover was maintained by the combined combat air patrol.

Kaga contributed 51 aircraft to the initial Midway strike at 04:30 on 4 June and had those aircraft returning between 08:30 and 09:00. Her second strike was being loaded through the following hour. At 10:22, when Akagi was struck by Richard Best's 1,000-pound bomb, Kaga was simultaneously being attacked by the dive bombers of USS Enterprise's VB-6 squadron under the command of Lieutenant Wilmer Earl Gallaher. Unlike the Akagi attack, which had involved a single bomb-carrying aircraft, the Kaga attack was delivered by 15 American Dauntlesses in quick succession.

Four American 1,000-pound bombs struck Kaga within ninety seconds. The first struck her forward flight deck; the second struck her port side amidships at the island; the third penetrated her flight deck near the starboard waist; the fourth struck her stern. The four strikes, combined with Kaga's armed aircraft on deck and her fuelling hoses in use at the moment of the attack, produced catastrophic damage.

The Disaster

The four bomb hits on Kaga between 10:24 and 10:25 on 4 June 1942 initiated a chain of fires that could not be controlled. The second bomb, striking at the island structure, killed Captain Jisaku Okada and most of her command staff on the bridge. The surviving senior officer was Commander Takahisa Amagai, Kaga's air group commander, who assumed command but could not establish effective damage control with her communications destroyed.

Kaga's fire behaviour was different from Akagi's and worse. Her larger aviation fuel capacity (2,000 tons of aviation gasoline, approximately 40 per cent more than Akagi's) ensured that her hangar fires were sustained for far longer. Her 1,200 crew, larger than Akagi's by 200 ratings, produced proportionally more casualties as the fires worked through the internal compartments. By 13:00 she was burning along her full length; by 14:00 her stern had begun to settle as the fires burned through her internal bulkheads.

She went through three separate periods of severe internal explosions during the afternoon: at 12:45 (when her forward aviation fuel tank exploded), at 13:40 (her after magazine), and at 15:30 (her main boiler room). The 15:30 explosion was the terminal event; after it she began to sink by the stern. Her destroyer escort Hagikaze moved alongside to evacuate her remaining crew. At 16:25 Commander Amagai ordered abandon-ship. Hagikaze and the destroyer Maikaze took off approximately 811 survivors. 811 of her 1,630 crew died, the highest death toll of the four Japanese carriers lost at Midway.

Kaga sank at 19:25 on 4 June 1942 at approximately 30°20′N 179°17′W in approximately 5,400 metres of water. She did not require scuttling torpedoes; her extensive fire damage caused her to roll and sink under her own weight.

The Legacy

The Midway losses of 4 June 1942 can be traced to two doctrinal errors in Japanese carrier operations: the practice of conducting fuel and armament changes on the hangar deck rather than in the magazine spaces, and the acceptance of slower aircraft-handling cycles than the American equivalents. Both errors were structural features of Japanese carrier design that could not be retrofitted in time to save the remaining Japanese fleet carriers during the war.

The specific question of which of the four Midway carriers should be regarded as the most tactically important loss has been the subject of ongoing historical debate. Kaga, by the highest casualty count, has a clear claim to the title. The destruction of her aviation fuel and armaments systems was the most severe of the four carriers; her 18 surviving D3A Val dive bombers, six A6M Zero fighters, and seven B5N Kate torpedo bombers represented approximately 27 per cent of her starting complement. She had also carried the most experienced carrier-qualified aircrew of any Japanese carrier of 1942: the loss of her air group's veterans at Midway had strategic consequences that extended far beyond the material loss of the aircraft themselves.

The wreck of Kaga was located in October 2019 by the Petrel expedition, 11 kilometres east-southeast of Akagi's wreck site. Kaga lies inverted on the Pacific abyssal plain, her inverted hull showing the extensive damage of her sinking: her port side is partially detached from the main hull, and her keel is broken near the stern. The Petrel imagery of Kaga's wreck has been studied in detail by American and Japanese naval historians because the inverted orientation of the hull has preserved features of the 1942 flight deck that would normally have been eroded by subsequent decades of ocean bottom currents.

The 811 dead of Kaga are commemorated at the Yasukuni Shrine. Their names have been read annually at the Japan Maritime Self-Defense Force memorial service at the Kure Naval Memorial Museum since the museum opened in 2005. The name Kaga was revived in 2017 for a Japan Maritime Self-Defense Force Izumo-class helicopter destroyer, JS Kaga (DDH-184), which is currently undergoing conversion to operate the F-35B Lightning II fighter. The new Kaga will be Japan's first conventional aircraft-operating ship since 1945. She is the direct inheritor of the name and the lineage.