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Mogami
Class overview
Name	Mogami class
Builders	Kure Naval Arsenal Mitsubishi Heavy Industries,Nagasaki Yokosuka Naval Arsenal Kawasaki Dockyard,Kobe
Operators	Imperial Japanese Navy
Preceded by	Takao class
Succeeded by	Tone class
Built	1931–1937
In commission	1935–1944
Completed	4
Lost	4
General characteristics
Type	Heavy cruiser
Displacement	8,500 tons (standard load, as reported) 10,980 tons (full load), approx. 11,000 tons (standard, actual displacement)
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)
Installed power	8–10Kampon boilers 152,000 shp (113,000 kW)
Propulsion	4 shafts; 4 gearedsteam turbines
Speed	37knots (69 km/h; 43 mph)
Range	8,000 nmi (15,000 km; 9,200 mi) at 14 knots (26 km/h; 16 mph)
Complement	850
Armament	(initial) 5 × triple15.5 cm/60 3rd Year Type guns (replaced by 5 × twin20.3 cm/50 3rd Year Type 2 guns from 1939) 4 × twin127 mm (5 in) guns 4 × single40 mm (1.6 in)AA guns 4 × triple 610 mm (24 in)torpedo tubes
Armor	Belt: 100 mm (3.9 in) Belt over magazine: 140 mm (5.5 in) Deck: 35 mm (1.4 in) Turrets: 25 mm (0.98 in) Magazines: 127 mm (5.0 in)
Aircraft carried	3 ×Aichi E13Afloatplanes

TheMogami class (最上型) was aship class of fourcruisers built for theImperial Japanese Navy (IJN) during the 1930s. They were initially classified aslight cruisers under the weight and armament restrictions of theLondon Naval Treaty. After Japan abrogated that agreement, all four ships were rearmed with larger guns and reclassified asheavy cruisers. All participated inWorld 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 theWashington Naval Treaty. This resulted in the choice of 155 mm (6.1 in) guns in five tripleturrets (a first for Japan) in theMogamis, also capable of 55° elevation, making theMogamis one of the very few classes of cruiser to have adual purpose (DP)main battery; this was coupled with very heavyanti-aircraft protection, as well as the standard reloadable, turretedtorpedo launchers, also unique to the IJN.^[1]

To save weight and improve transverse stability, the class was given a more compact and lowersuperstructure, made ofaluminium, which waswelded rather than riveted.^[2] Only tenboilers could be fit under the weight limits (compared to twelve in the previousTakao andMyōkō classes), and the chimney arrangement was designed to minimize weight as well; the middle funnel featured nochimney of its own, instead venting its exhaust gasses into the underside of the forward chimney, which itself was reclined from its base so that, at its top, it merged with the aft funnel's chimney. The newgearedimpulse turbines added 22,000shaft horsepower (16,000 kW) overAtago, increasing the top speed by 1.5knots (2.8 km/h; 1.7 mph). 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.^[3] “They must be building their ships out of cardboard or lying” said the Royal Navy’s Director of Naval Construction (DNC) in 1935 when briefed by Naval Intelligence about the public displacement figure announced by the Japanese.^[4]

The designers, however, had overreached; excessive topweight led to instability, and gunnery trials revealed cracking hull welds. Hull bulges were retrofitted toMogami andMikuma, and added toKumano andSuzuya, increasingbeam to 20.5 m (67 ft) anddisplacement to 11,200 tons, cutting speed by 2 knots (3.7 km/h; 2.3 mph).^[5]

Following Japan's withdrawal from theSecond London Naval Treaty, plans were made to modernize and expand the entire fleet. Beginning in 1939, the class was brought in for substantial reconstruction, replacing the triple 155 mm turrets with twin203 mm (8-inch) guns, turning over the 155 mm turrets for thebattleships of theYamato class.^[6] 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 theLondon Naval Treaty, though the Japanese had withdrawn from the conference and were not signatories to theSecond London Naval Treaty of 1936.

Torpedo bulges were also added; in all, displacement rose to over 13,000 tons, and speed dropped to 35 knots (65 km/h; 40 mph).

All four ships participated in the Japanese invasion of theDutch East Indies.Mogami andMikuma were present at theBattle of Sunda Strait and contributed to the sinkings of the cruisersHMAS Perth andUSS Houston.

In June 1942, all four took part in theBattle of Midway, whereMogami andMikuma collided trying to avoid asubmarine attack;Mikuma was finished off on 6 June 1942 by aircraft fromaircraft carriersUSS Enterprise andHornet. The heavily damagedMogami 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 theBattle of Leyte Gulf.Mogami, heavily damaged by a collision with the cruiserNachi, cruiser gunfire, and aerial attack, wasscuttled by the destroyerAkebono, whileKumano limped intoManila harbor on one boiler, to be sunk byHalsey's aviators on 25 November 1944; the USescort carrier planes mauledSuzuya at Leyte, which was scuttled by the destroyerOkinami on 25 October.

• Blair, Clay (1975).Silent Victory. London: Lippincott.
• Dull, Paul S. (1978).A Battle History of the Imperial Japanese Navy, 1941-1945. Annapolis, Maryland: Naval Institute Press.ISBN 0-87021-097-1.
• Jentschura, Hansgeorg; Jung, Dieter & Mickel, Peter (1977).Warships of the Imperial Japanese Navy, 1869–1945. Annapolis, Maryland: United States Naval Institute.ISBN 0-87021-893-X.
• Lacroix, Eric; Wells II, Linton (1997).Japanese Cruisers of the Pacific War. Annapolis: Naval Institute Press.ISBN 0-87021-311-3.OCLC 21079856.
• Preston, Antony (2004).World's Worst Warships. London: Conway's Maritime Press.
• Rohwer, Jürgen (2005).Chronology of the War at Sea 1939–1945: The Naval History of World War Two (Third Revised ed.). Annapolis, Maryland: Naval Institute Press.ISBN 1-59114-119-2.
• Sturton, Ian (1980). "Japan". In Chesneau, Roger (ed.).Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press.ISBN 0-85177-146-7.
• Whitley, M. J. (1995).Cruisers of World War Two: An International Encyclopedia. London: Cassell.ISBN 1-86019-874-0.

Wikimedia Commons has media related toMogami class cruiser.

• Hackett, Bob; Sander Kingsepp (2006)."Mogami class".Imperial Japanese Navy Page (Combinedfleet.com). Retrieved14 June 2006.

• Cruiser classes
• Mogami-class cruisers
• Cruisers of the Imperial Japanese Navy

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