Mutsu

Construction

Yokosuka Naval Yard; Yokosuka, Japan

Laid down: 1 June 1918

Launched: 31 May 1920

Commissioned: 22 November 1921

Specifications

32,700 tons displacement, standard

215.8m length

28.96m beam

9.08m draft

Machinery

20 boilers, 4 turbines

Performance

26.7 knots at 80,000 shaft horsepower

5,500 nautical miles at 16 knots

Armor

Main belt: 102-305mm

Decks: 38-76mm main

Barbettes and Turrets: 305mm barbette, 305mm turrets

Casemates: 25mm

Conning tower: 368mm

Armament

Eight (4x2) 410mm guns, twenty (20x1) 140mm guns, four (4x1) 78mm guns, and four (4x1) 533mm torpedo tubes.

History

Design

The Nagato-class Battleships were the last pair of battleships build by the Japanese Navy before the global hiatus on capital ship construction due to the ratification of the Washington and subsequent London naval treaties. As such, the Nagato-class is seen as the culmination of all the experience learned by the Japanese Navy in dreadnought design and construction up to the end of World War I.

Under the lead of the famed Hiragana Yuzuru, construction of the Nagato-class began in 1916. By now, Japan was a steadfast growing naval power and wanted their designs to reflect such a status. As such, from the very genesis, the Nagato-class were set to be first-rate dreadnoughts; competitive amongst the offerings of the other navies, namely the Colorado-class Battleships that were being built by the US. They were meticulous from the beginning; delaying draft completion to 1917 in order to incorporate the lessons learned from the Battle of Jutland during World War I. What emerged were the most advanced battleships afloat in the World.

The Japanese determined that high-speed was an integral asset that makes battleships an effective weapon, as such, the Nagato-class were designed to be the fastest battleships in the World. It was decided to fit no less than 21 Kampon boilers: 15 oil-fired and 6 mix-fired. They fed into 4-geared turbines that each powered a single screw. The generated 80, 000 shaft horsepower propelled the ships to above 26 knots; faster than the competition. But this was not a specification the Navy boasted; instead electing to keep the true speed a guarded secret. In fact, the US navy didn’t know the true speed of the class until well into the late 1930s.

In electing to focus on the propulsion, weight had to be saved from the armouring. Ergo, the Japanese opted to implement the “all-or-nothing” armour principle that was championed by the US; maximal armour to the vital areas whist non-critical surfaces receives minimal armour. The main belt and the barbette rings received 12-inches in armour, whilst the conning tower and the turret faces received 14-inches and 18-inches in armour, respectively. While this is sufficient to rival other battleships of the period it was a fact that British and US battleships all had greater armouring; belt armours exceeding 13-inches for instance.

After experimentation with 6-turret designs, the designers decided to revert back to a quadruple turret design; determining this configuration to be the most effective. But in order to not decrease overall firepower by reducing 12 guns to just 8, the calibre of rifle was increased from the traditional 14-inch to 16-inches; in fact, the Nagato-class battleships were the first ships to mount 16-inch naval rifles. To supplement the primary artillery, 20 5.5-inch casement guns were added to the hull. Interestingly, the Nagato-class retained the Japanese tradition of fitting torpedo tubes to their battleships. Historically 8 in total were added; 4 above water and 4 submerged.

Mutsu is the second of the two Nagato-class battleships, built at the Naval Arsenal, in Yokosuka. She was laid down 1 June 1918, launched 31 May 1920 and completed 24 October 1921.

The Nagato-class underwent a modernization in the late 1920s and a reconstruction in the 1930s to keep the designs combat-capable. During the 1920s modernization, the first funnel was replaced with a serpentine funnel with a raked-top in order to attempt to fix the issue of the superstructure being occluded with smoke; the very funnel seen in-game. Furthermore, torpedo tubes were traded-in for anti-aircraft artillery, in order to counter the growing threat of aircraft. Unique to Mutsu, her bow was remodelled in order to decrease water spray to her foredeck. The 1930s reconstruction proved to be a more extensive overhaul. The iconic 7-masted superstructure was replaced with a pagoda-mast style design, and the first funnel was removed altogether. The old boilers were replaced; the overall number was also reduced to just 10. Furthermore, torpedo bulges were introduced. To mitigate the loss in ship speed due to the added weight, the length of the battleships were increased. Finally a catapult was added to launch scout planes off the deck.

Service

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  Mutsu under construction at Yokosuka Naval Shipyard, 24 September 1920.

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  Mutsu fitting out at Yokosuka.

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  Mutsu at anchor shortly after completion, circa 1922.

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  Mutsu anchored at Sasebo, 28 May 1925.

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  Mutsu (far left), Tenryu (left), HMS Hermes (center), and Fuso (right) anchored in Victoria Harbor, Hong Kong, 14 April 1928.

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  Mutsu on sea trials off Yokosuka following her reconstruction, 27 July 1936.

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  Mutsu at sea following her reconstruction, circa 1936.

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  Mutsu anchored at Yokosuka, February 1937.

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  Mutsu anchored at Kagoshima, circa 1941. The extensive torpedo bulges added during reconstruction are clearly visible.

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  An up close and personal view of the forward turrets in Mutsu’s main battery.

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  US Office of Naval Intelligence recognition drawing of a Nagato-class battleship.

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  Mutsu’s original No. 4 turret — removed during her reconstruction period in the mid-1930's — on display at the grounds of the former Imperial Japanese Naval Academy at Etajima, circa 1947.

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  In the early 1970's, salvage operations were conducted that removed large portions of Mutsu’s wreck from the ocean. This is turret No. 3 following its removal from the wreck in 1971.

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  A 140mm 3rd Year Type naval gun salvaged from Mutsu is on display at the Yasukuni Museum in Tokyo, Japan.

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  One of Mutsu’s 410mm guns is on display outside the Yamato Museum in Kure, Japan.

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  Another of Mutsu’s 410mm guns is on display outside the Museum of Maritime Science in Tokyo, Japan.