Akagi (Red Castle)

The Akagi (Red Castle) was the oldest of the six aircraft carriers that took part in the Japanese attack on Pearl Harbor, and as the flagship of the Vice Admiral Nagumo became the most famous of all the Japanese carriers.

The Akagi was laid down in December 1920 as one of four 41,200 ton battlecruisers, but work was suspended in February 1922 after the Washington Naval Treaty imposed limits on naval construction. By then all four of the ships had been laid down, Amagi and Akagi in 1920 and Atago and Takao in 1921.

Nakajima B5N1 'Kate' taking off from Akagi
Nakajima B5N1 'Kate'
taking off from Akagi

The Imperial Navy’s first aircraft carrier, the Hosho, was completed in December 1922, and the navy soon realised that it needed larger faster carriers, capable of operating with the battleships of the main fleet. The partially constructed Amagi class battlecruisers were ideally suited for conversion to the new role, with their large hulls and powerful engines. The Navy decided to convert Amagi and Akagi, while the less complete Atago and Takao were both scrapped.

Work on converting the Amagi began early in 1922, but her hull was badly damaged during the Tokyo earthquake, and she was officially stricken on 31 July 1922. Work on converting the Akagi began later, on 19 November 1923, while the Amagi was replaced by the fast battleship Kaga. The Akagi was launched in April 1925, and completed as an aircraft carrier on 25 March 1927.

The Akagi of 1927 was a most unusual looking ship. She had a 624ft long flight deck that ran along two thirds of the ship’s length, stopping 220ft short of the bow. This main deck was used for landing aircraft. Below this main deck were two hanger decks. Each of these hanger decks had a flying off platform positioned forward, giving the ship three staggered flight decks. 

This design was not a great success, and between 24 October 1935 and 31 August 1938 she was extensively rebuilt. The new Akagi emerged as a standard aircraft carrier of the period, with a single full length flight deck, two larger hangers served by three elevators and a small port side island. Aircraft capacity increased to either 66 operational aircraft with 15 reserves, or 72 aircraft with 19 reserves (sources differ).

The modified Akagi retained six of her original ten 8in guns, mounted in casemates that were too low in the ship to be useable in rough seas. Antiaircraft defence was provided by 12 4.7in guns in six dual mounts and 28 25mm anti-aircraft guns in fourteen twin mounts.

The Akagi was the flagship of the First Air Fleet during the victorious months after the Japanese entry into the Second World War. In this role she took part in the attack on Pearl Harbor. As Admiral Nagumo’s flagship she took part in the attack on Darwin of 19 February 1942, launching her aircraft from a position east of Timor Island. The purpose of this attack was to shield the Japanese invasion of Timor, but the raid caused an invasion scare in Australia.

Midway Pictures
Midway: Akagi under B-17 attack during Battle of Midway

The Akagi was then one of five carriers that Nagumo took into the Indian Ocean in April 1942, attacking Ceylon and sinking a number of ships from the British Eastern Fleet.

The Akagi’s luck ran out during the battle of Midway (June 1942). Three Douglas SBD Dauntless dive bombers from VB-6 (bombing squadron six, USS Enterprise) attacked her just after 10:20 on 4 June and scored two hits and a damaging near miss. The hits caused massive fires, and jammed the rudder.

Despite the raging fires the Akagi remained afloat until the morning of 5 June. Admiral Nagumo was forced to transfer his flag at 10:46 on 4 June, twenty minutes after the attack. The engines stopped three-quarters of an hour after the bomb hits, but were restarted at 12:03. With the rudder jammed, the Akagi could only circle to the starboard. At 13:38 the Emperor’s portrait was removed from the ship, a sure sign that the end was near. Twelve minutes late the engines failed again, and at 14:00 the survivors abandoned ship. Even then the Akagi refused to sink, and early on the morning of 5 June she was torpedoed by the destroyers Nowake, Arashi and Hagikaze.

Displacement (standard)

36,500t (after 1938)

Displacement (loaded)

42,750t (after 1938)

Top Speed



8,200nm at 16kts

Armour – deck


 - turrets



60 as built
72 operational, 91 maximum after 1939


855ft 4in maximum

Armament as built

10 8in/50 guns (two in double mountings, six in single mountings
12 4.7in AA guns (six double mountings)
22 machine guns

Armament from 1938

6 8in/60 guns (single mountings)
12 4.7in AA guns
28 25mm AA guns

Crew complement



22 April 1925


25 March 1927

Sunk at Midway

5 June 1942

Midway: Dauntless Victory, Fresh Perspectives on America's Seminal Naval Victory of World War II, Peter C. Smith. A very detailed and well researched account of the battle of Midway and of the historical debate that still surrounds it, supported by a mass of original documents and interviews with participants. An invaluable look at this crucial battle. [see more]
cover cover cover

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How to cite this article: Rickard, J (27 November 2008), Akagi (Red Castle) , http://www.historyofwar.org/articles/weapons_akagi.html

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