Mutsu

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 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 through the end of World War I.

Led by famed naval architect Yuzuru Hiraga, planning and design for the Nagato-class began in 1916. By this time, Japan was a steadfast, growing naval power and wanted their designs to reflect such a status. As such, from the outset the Nagato-class were set to be first-rate dreadnoughts, competitive with the offerings of the other navies of the world (chiefly the Colorado-class battleships that were being built by the United States). Hiraga and his team were meticulous, delaying final completion of her plans until mid-1917 in order to incorporate the lessons learned from the Battle of Jutland the previous year. What ultimately emerged were the most advanced battleships afloat in the world.

The Japanese determined that high-speed was an integral asset to making a battleship 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 twenty-one (21) Kampon boilers into them: fifteen (15) oil-fired and six (6) mix-fired. These boilers then fed into four (4) geared turbines that each powered a single screw. Altogether, they generated 80,000 shaft horsepower and propelled the ships to speeds above 26 knots, significantly faster than their competition. This was not a fact the Japanese Navy boasted about, however, instead electing to keep the true speed a closely 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 propulsion and speed, weight had to be saved from the armoring. Ergo, the Japanese opted to implement the “all-or-nothing” armor principle that was championed by the US; maximal armor to the vital areas whist non-critical surfaces receives minimal armor. The main belt and the barbette rings received 12 inches of armor, whilst the conning tower and the turret faces received 14 inches and 18 inches of armor, respectively. While this was sufficient to rival other battleships of the period, British and US battleships all had heavier armor, with belt armors exceeding 13 inches for many classes.

After experimentation with the six turret design of the Fuso and Ise classes, Hiraga and his designers decided to revert back to a quadruple turret design, determining this configuration to be the most effective. In order to not decrease overall firepower — by reducing the number of barrels from 12 to 8 — the caliber each rifle was increased from the traditional 14 inches to 16 inches; in fact, the Nagato-class battleships were the first ships in the world to mount 16-inch naval rifles. To supplement the primary artillery, twenty (20) 5.5-inch casemate guns were added to the hull. Interestingly, the Nagato-class retained the Japanese tradition of fitting torpedo tubes to their battleships. Historically, eight (8) total tubes were incorporated in the design; four (4) above the waterline and four (4) submerged (only the four above the waterline are available in-game).

Mutsu (陸奥, named after Mutsu Province) was 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, the torpedo tubes were traded-in for anti-aircraft artillery, in order to counter the growing threat of aircraft. Unique to Mutsu, her bow was remodeled 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 ten (10). Interestingly, the old turrets were replaced by the ones of the incomplete Tosa class battleships, allowing for greater gun elevation, ergo greater range. 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

Commissioned in October 1921, Mutsu survived the Washington Naval Treaty, was assigned to BatDiv (Battleship Division) 1, and began an uneventful interwar career. From 1927 to 1933, Mutsu would receive periodic modifications, but in September 1934 she entered drydock for a complete rebuild and modernization. She remained in yard hands until September 1936.

With the beginning of war with China in July 1937, Mutsu — having returned to BatDiv 1 alongside Nagato — joined the fleet for security and blockade patrols off the China coast. Mutsu would continue operations off China until March 1941. In August 1941, Mutsu began preparations for combat as Japan planned for hostilities with the United States.

Mutsu would spend the beginning of World War II, from December 1941 to May 1942, in reserve and training. In June, she and the rest of BatDiv 1 — now including Yamato — sortied as part of the Main Body for Operation MO, the invasion of Midway. Other than to receive the transfer of survivors from Akagi, Kaga, Hiryu, and Soryu, Mutsu would not participate in the battle, and returned to Japan.

In July, BatDiv 1, less Yamato, was attached to the 2nd Fleet. In August, they departed for Truk after the US landing at Guadalcanal. In late August, Mutsu was assigned to support the Main Body for the Battle of the Eastern Solomons, where she fired at an aircraft shadowing the fleet. This would prove to be her only shots fired in combat during the war.

In September, Mutsu landed a party to help train anti-aircraft crews at Truk. She would remain and participate in exercises until January 1943, when she returned to Japan. Excepting one aborted sortie to the Aleutians after the Battle of the Komandorski Islands in late March 1943, Mutsu continued to conduct training and gunnery exercises until June 1943.

On 8 June 1943, Mutsu was moored in Hashirajima harbor when, at approximately 1200 hours, her No. 3 turret suffered an explosion. The blast tore her in two, and the section forward the No. 3 turret rolled over and quickly sank. Her stern section sank early the next day. Of her 1,474 crew, 1,121 were killed. An investigation concluded human error was responsible for the explosion, and the Japanese Navy consequently altered regulations for the handling of explosives aboard ships.

Mutsu was struck from the Navy List on 1 September 1943.

Post-war salvage attempts proved to be failures, though Mutsu’s No. 4 turret, anchors, and other parts of the ship — including her bow — were successfully recovered in the 1970s. The gun barrels from the salvaged No. 4 turret were restored and are now on display in separate locations in Japan: one at the Museum of Maritime Science in Tokyo, and the other outside the Yamato Museum in Kure.

Historical Inaccuracies

• Light and dark green camouflage was only applied to aircraft carriers in 1944; Mutsu is in 1933 configuration. Demounting the premium camouflage will reveal the ship's historical appearance (albeit with moderate rust), but at the cost of the camouflage's bonuses.

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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 underway, 19 October 1921.

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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 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. 4 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.