Mogami class cruiser

IJN Mikuma, 1939
Class overview
Operators:  Imperial Japanese Navy
Preceded by: Takao class cruiser
Succeeded by: Tone class cruiser
Built: 1931–1937
In commission: 1935–1944
Completed: 4
Lost: 4
General characteristics
Type: Heavy cruiser
Displacement: 8,500 tons (standard load) 10,980 tons (full load)
Length: 201.6 m (661 ft 5 in)
Beam: 20.6 m (67 ft 7 in) (Mogami class)
20.2 m (66 ft 3 in) (Suzuya class)
Draft: 5.5 m (18 ft 1 in)
Propulsion: Four-shaft impulse single geared turbines
10 Kampon boilers (Mogami class)
8 Kampon boilers (Suzuya class)
152,000 shp
Speed: 37 knots (43 mph; 69 km/h)
Range: 8,000 nmi (15,000 km) at 14 kn (16 mph; 26 km/h)
Complement: 850

• 15 × 155 mm (6.1 in)/60-cal Dual purpose guns (5×3) (replaced by 10 x 20 cm/50 3rd Year Type 2 GÔ guns (5x2) from 1939)
• 8 × 127 mm (5.0 in)/40-cal DP guns (4×2)
• 4 × 40 mm AA guns

• 12 × 610 mm (24 in) torpedo tubes (4×3)
Armor: Belt: 100 mm (3.9 in)
Deck: 35 mm (1.4 in)
Turrets: 25 mm (0.98 in)
Magazines: 127 mm (5.0 in)
Aircraft carried: 3 × Aichi E16A reconnaissance floatplanes

The Mogami class (最上型?) were a class of four heavy cruisers built for the Imperial Japanese Navy (IJN) in the mid-1930s. All four fought in World War II, and were sunk.



For the 1931 Fleet Replenishment Program, believing themselves understrength in cruisers, the IJN chose to build to the maximum allowed by the Washington Naval Treaty. This resulted in the choice of 155 mm (6.1 inch) guns in five triple turrets (a first for Japan) in the Mogamis, also capable of 55° elevation, making Mogamis one of the very few classes of Cruiser to have a Dual Purpose (DP) main battery; this was coupled with very heavy anti-aircraft protection, as well as the standard reloadable, turreted torpedo tubes, also unique to the IJN.

To save weight, electric welding was used, as was aluminium in the superstructure. Aiming to meet the weight limits compelled them to fit only ten boilers (compared to twelve in the previous Takao and Myoko classes), trunked into a single funnel stack (which also saved tophamper). The new impulse geared turbines added 22,000 shp over Atago, increasing the top speed by 1.5 knots (2.8 km/h). Protection, however, was not stinted on; the class proved able to take substantial punishment.

The declared weight was 8,500 tons, though the true design weight was 9,500 and at trials they would displace 11,169 tons.[1]

The designers, however, had overreached; excessive topweight led to instability, and gunnery trials revealed cracking hull welds. Hull bulges were retrofitted to Mogami and Mikuma, and added to Kumano and Suzuya, increasing beam to 19.2 m (63 ft) and displacement to 11,200 tons, cutting speed by 2 kt (3.7 km/h).

Beginning in 1939, the class was brought in for substantial reconstruction, replacing the triple 155 mm turrets with twin 203 mm (8-inch) guns, turning over the 155 mm turrets for the battleship Yamato. Indeed, the designers had designed the class in mind so that the 6-inch guns could be switched with 8-inch batteries, in effect making them heavy cruisers and skirting the London Naval Treaty, though the Japanese had withdrawn from the conference and were not signatories to the Second London Naval Treaty of 1936.

Torpedo bulges were also added; in all, displacement rose to over 13000 tons, and speed dropped to 34.5 kt (63.8 km/h).

The United States Navy's Brooklyn-class cruisers were designed specifically to counter the Mogami class, and as a result had a very similar armament to the pre-refit Mogamis, in a nearly identical layout.

War Service

All four ships participated in the Japanese invasion of the Dutch East Indies. The Mogami and Mikuma were present at the Battle of Sunda Strait and contributed to the sinkings of HMAS Perth and USS Houston.

In June 1942, all four took part in the Battle of Midway, where Mogami and Mikuma collided trying to avoid a submarine attack; Mikuma was finished off on 6 June 1942 by aircraft from USS Enterprise and Hornet. The heavily damaged Mogami limped home and spent ten months in yard, during which her afterparts were completely rebuilt, and "X" and "Y" turrets were replaced by a flight deck (with the intention to operate 11 aircraft).

In October 1944, the survivors were reunited at the Battle of Leyte Gulf. Mogami, heavily damaged by a collision with Nachi, cruiser gunfire and aerial attack was scuttled by Akebono, while Kumano stumbled into Manila harbor on one boiler, to be put out of her misery by Halsey's aviators on 25 November 1944; they mauled Suzuya the same day, and she was scuttled by Okinami on 27 November.


This class is seen by naval architects as trying to fit a quart into a pint pot. The IJN's Naval staff insisted that each new class be superior to anything else in its category, this placed an enormous burden on Japanese naval constructors and the difficulties with these ships have to be seen in this light.

The initial construction was extremely light in order to comply with the naval treaties and had to be remedied. When the Royal Navy's Director of Naval Construction (DNC) was told about these ships, by British Naval Intelligence quoting the public displacement figure, he replied that the capabilities quoted could not be achieved on this displacement and that "they must be building their ships out of cardboard or lying".

Though the placement of Turret #3 improved its firing arc, and though the class had the stability problems fixed (the preceding Takao-class cruisers were considered too top-heavy), the Mogamis are generally not considered an improvement over the Takaos[1]. Nonetheless, the follow-up Tone-class retained many aspects of the Mogami-class design. However, the Tones were intended for a different purpose with all of their main armament forward, so their stern could accommodate extra floatplanes.


Sub class Name Builder Laid Launched Completed Fate
Mogami Mogami (最上) Kure Naval Arsenal 27 October 1931 14 March 1934 28 July 1935 Sunk during the Battle of Leyte Gulf on 25 October 1944
Mikuma (三隈) Mitsubishi Nagasaki Shipyard 24 December 1931 31 May 1934 29 August 1935 Sunk during the Battle of Midway on 5 June 1942
Suzuya Suzuya (鈴谷) Yokosuka Naval Arsenal 11 December 1933 20 November 1934 31 October 1937 Sunk during the Battle off Samar on 25 October 1944
Kumano (熊野) Kōbe-Kawasaki Shipbuilding Yard 5 April 1934 15 October 1936 31 October 1937 Sunk during the Philippine campaign on 25 November 1944 by aircraft of USS Ticonderoga


  1. ^ Brown, Nelson to Vanguard p 74
  • Blair, Clay (1975). Silent Victory. London: Lippincott. 
  • D'Albas, Andrieu (1965). Death of a Navy: Japanese Naval Action in World War II. Devin-Adair Pub. ISBN 0-8159-5302-X. 
  • Dull, Paul S. (1978). A Battle History of the Imperial Japanese Navy, 1941-1945. Naval Institute Press. ISBN 0-87021-097-1. 
  • Fitzsimons, Bernard (1978). "p. 1927-8". The Encyclopedia of 20th Century Weapons and Warfare, Volume 18. London: Phoebus. 
  • Lacroix, Eric; Linton Wells (1997). Japanese Cruisers of the Pacific War. Naval Institute Press. ISBN 0-87021-311-3. 
  • Preston, Anthony (2004). World's Worst Warships. London: Conway's Maritime Press. 
  • Miller, David (2004). "Page 242". The Illustrated Directory of Warships from 1860 To The Present Day. London: Greenwich Editions, Salamander Books Ltd. ISBN 0-86288-672-5. 

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