Japanese battleship Mutsu

Mutsu at anchor
History
Laid down	1 June 1918
Launched	31 May 1920
Commissioned	24 October 1921
Fate	Sunk by internal explosion, 8 June 1943
General characteristics
Displacement	42,850 tons
Length	221.03 m (725 ft 2 in) 215.79m (708 ft) at launch
Beam	34.59 m (113 ft 6 in) 29m (95 ft) at launch
Draught	9.50 m (31 ft 2 in)
Propulsion	Geared turbines, 4 shafts, 80000 hp (60 MW)
Speed	27 knots (50 km/h; 31 mph)
Range	5,500 nautical miles at 16 knots (10,200 km at 30 km/h)
Complement	1,368
Armament	Eight 16 inch (406.4 mm) guns Twenty (later eighteen) 5.5 inch (140 mm) guns Eight 5 inch (127 mm) anti-aircraft guns Up to 98 25 mm AA guns
Aircraft carried	3

Mutsu shortly after commissioning in c. 1922

Mutsu (陸奥), named after Mutsu Province, as per Japanese ship naming conventions, was the Imperial Japanese Navy's (IJN) second Nagato class battleship. When commissioned in 1921, she and her sister-ship were the first battleships in the world with 16 inch (406.4 mm) guns and were considered the Japanese navy equivalents of the British Navy’s Queen Elizabeth class. At the time of their completion in 1920–21, their armament, armour and speed made them the most powerful capital ships in the world and they remained the most powerful battleships in the Imperial Japanese Navy until the completion of the Yamato class. It was not until 1937 that the US Navy became aware that their actual speed was considerably higher than the 23 knots they had previously assumed, which resulted in a redesign of the South Dakota class to provide them with a higher speed.

The Nagato class were extensively modified in the 1920s and 1930s after the Washington Naval Treaty of 1922 limited the battleship tonnage of the Japanese (and other) navies and allowed no new construction for several years. As a result of the treaty, they were the last battleships built by Japan until the Yamato class battleships of the late 1930s.

The sparing of Mutsu was a condition of the Japanese Government's signing the Washington Naval Treaty. Not only was she was the most modern and powerful ship in the fleet at the time, she was also the first battleship designed by Japanese naval architects. Her construction had been funded by public subscription, most notably Japanese school children, which meant that she was greatly admired by the Japanese people. As a result it would have been domestically and politically unacceptable to scrap her so soon after her construction. The battleship Settsu was decommissioned instead.

Design

Main article: Nagato class battleship

She was authorised in 1917 and allocated the design number A-102 the Mutsu was designed by Captain Yuzuru Hiraga.

Construction

Laid down at the Yokosuka Naval Arsenal on 1 June 1918, the Mutsu was launched on 31 May 1920, and commissioned on 24 October 1921.

As commissioned

Upon her completion the Mutsu had a displacement of 34,116 tons while her 21 coal-fired boilers powered four geared Gihon turbines that developed a total of 82,000 shp, which allowed her to reach a trial speed of 26.728 knots (49.500 km/h; 30.758 mph).

Despite the front funnel being 2 metres (6 ft 7 in) higher than the rear one to reduce smoke interference to the gunnery control positions of the front mast, operational experience led to the front funnel being fitted with a smoke deflector in 1922 shortly after test trials were completed. To further reduce smoke interference, the top of the fore funnel was curved back 8 metres (26 ft) between August 1924 and March 1925. The Mutsu was fitted with a clipper bow in 1927.

Four twin dual purpose 5-inch (127-mm) HA (high angle) guns were installed in 1932, the existing 3-inch (76-mm) AA guns were removed.

Reconstruction and modernization

She underwent major reconstruction at the Yokosuka Navy Yard between 5 September 1934 and 30 September 1936, in which her hull was lengthened to 737 feet (225 m) and anti-torpedo bulges and a triple bottom were added. Horizontal armour was increased over the engine room and magazines and additional armour was also fitted to the faces, sides and tops of her main turrets, the barbette armour was also strengthened. Additions to the fore-mast led to her acquiring the distinctive pagoda mast that became the distinguishing feature of Japanese battleships of her era. She lost her submerged torpedo tubes and two of her upper deck secondary guns. The elevation of her main 16-inch guns was increased from −5 / +30 to −3 / +43 degrees, which increased their maximum range to 33,930 yards (31,025 m) when firing a 2,069 lbs shell. (938.5 kg) HE shell and 42,350 yards (38,725 m) when firing a 2,249 lbs projectile or an (1,020 kg) APC (armour-piercing capped) shell. The elevation of the remaining 5.5-inch guns was increased to 35 degrees. Eight 127 mm dual-purpose guns in four twin mounts and twenty Type 96 25mm anti-aircraft guns in ten twin mounts were added to increase her anti-aircraft protection. A 19.6 metre long Kure Type No. 2 Model 5 catapult and a collapsible crane were fitted forward of "C" turret for three Nakajima E4N2 floatplanes which were to be carried for observation purposes.

All twenty original coal-fired steam boilers were replaced by four new large Kampon and six smaller re-built oil fired units, which developed 92,000 shp, extended the range and allowed her to maintain close to her original speed despite the increased drag of the torpedo bulges and the weight of the additional armour which had increased her standard displacement to 42,785 tons. During trials on 27 July 1936 she attained a speed of 25.283 knots. The changes in her boilers allowed her front funnel to be removed although her rear funnel was enlarged.

The completion of her reconstruction was her last significant modification until 1941 when she was fitted with external degaussing coils and the anti-torpedo bulges were filled with crushing tubes.

Service and World War II

After commissioning the Mutsu served in the First Battleship Division of the First Fleet. Upon completion of her modernisation she rejoined the First Battleship Division.

During World War II Mutsu saw limited action, spending much of her time in home waters. Mutsu, as part of a covering force for the Pearl Harbor task force forayed from Hashirajima to the Bonin Islands from 8 to 13 December 1941, in company with the light carrier Hosho and the First Fleet's Battleship 2 division's Ise, Hyuga, Fusō, and Yamashiro, escorted by light cruisers and destroyers. The group saw no action.

The Mutsu departed Hashirajima as part of the Battleship Division First Fleet's Main Body under the command of Admiral Isoroku Yamamoto on 29 May 1942 in company with the battleships Yamato, Nagato, the aircraft carrier Hosho, the cruiser Sendai, nine destroyers and four auxiliary vessels to provide support to Operation “MI”, the Japanese Navy’s attempt to take the island of Midway. During the resulting battle the Mutsu remained with the main body 300 miles behind Vice Admiral Nagumo's First Carrier Striking Force, and did not engage US forces. At the end of the battle the Mutsu joined up with the retiring Carrier Striking Force on 5 June and took aboard about one-half of the survivors from the carriers Akagi, Kaga, Soryu and Hiryu that had been picked up earlier by covering destroyers and also refuelled a number of destroyers. On 14 June the Mutsu returned to her home anchorage in Hashirajima.

In July the Mutsu was transferred from the Battleship Division 1 to the Battleship Division 2 which was allocated to training and 'standby alert' duties.

The Mutsu departed Yokosuka accompanied by the cruisers Atago, Takao, Maya, Haguro, Yura, Myoko, the seaplane tender Chitose and escorting destroyers on 11 August to support operations during the Guadalcanal Campaign. The task force arrived at the major Japanese base at Truk on 17 August 1942. On 20 August, while sailing from Truk to rendezvous with the main body of Vice Admiral Nagumo's Third Fleet, the Mutsu, the cruiser “Atago’’ and escorting destroyers, in response to a flying boat detecting the escort carrier USS Long Island ferrying aircraft, attempted to locate the American ship. No contact was made.

During the battle of the Eastern Solomon islands on 27 August, Mutsu fired four shells at tracking enemy aircraft during what was her first and only action of the war. Following her return to Truk a group of skilled AA gunnery officers and men were detached from the Mutsu to serve as instructors to ground-based naval anti-aircraft gunners stationed in Rabaul. During her time at Truk the Mutsu off-loaded surplus fuel to the fleet oil tanker Kenyo Maru which allowed the tanker to refuel other ships involved in Guadalcanal operations.

On 7 January 1943, the Mutsu steamed from Truk via Saipan to return to Japan in the company of the carrier Zuikaku, the cruiser Suzuya and the destroyers Inazuma, Isonami and Ariake. Upon her return to Hashirajima, Mutsu resumed 'standby alert' duties.

The Mutsu left Hashirajima for Kure on 13 April, where in response to the situation in the Komandorski Islands, she took aboard a full load of ammunition and supplies and prepared to participate in a sortie to reinforce the Japanese garrisons in the Aleutian Islands, but the situation changed and she was never dispatched.

Loss

On Tuesday 8 June 1943 the Mutsu was moored at the Battleship Division 2 flagship buoy No.2 in the Hashirajima fleet anchorage approximately 3 km (1.9 mi) south-west of the island of Hashirajima and just to the west of Mitsuhima island in the Inland Sea, hosting 113 flying cadets and 40 instructors from the Tsuchiura Naval Air Group on a familiarization tour. At 12:13 the magazine of her No. 3 turret exploded. The explosion was so severe that it instantly sheared the stern from the ship forward of No. 3 turret, causing major flooding in the boiler rooms and main engine room. The 535-foot (163 m) forward section of the ship rolled to starboard and sank almost immediately. The stern section upended and remained floating until about 0200 hours on 9 June before sinking, coming to rest a few hundred feet south of the main wreck.

The battleship Fuso immediately launched two boats which, together with assistance from the destroyers Tamanami, Wakatsuki, the cruisers Tatsuta and Mogami, were able to rescue 353 survivors from the 1,474 crew members and visitors aboard Mutsu, giving a loss of 1,121. Only 13 of the visiting flying cadets/instructors were among the survivors. During the initial and later salvage operations, lasting until 1978, all but 272 of the bodies were recovered. Since 1963, a memorial service is held every year on 8 June in Tôwa Chô in honour of the crew.

After the explosion, as the rescue operations commenced, the fleet was mobilized and the area was combed for Allied submarines and X-craft, but no traces were found.

To avert the potential damage to morale of the loss of a battleship coming so soon after the string of recent setbacks in the war effort, Mutsu's loss was declared a state secret. Mass cremations of recovered bodies began almost immediately after the sinking. Captain Miyoshi's body was recovered from his cabin by divers on 17 June, his wife was not officially notified until 6 January 1944, how he had died was not mentioned. Both he and his second in command, Captain Ono Koro, were posthumously promoted to Rear Admiral, which was normal Japanese Navy practice. 39 wounded survivors were sent to a secluded hospital on Mitsukoshima.

To further prevent rumours from spreading, healthy and recovered survivors were re-assigned to various garrisons in the Pacific Ocean. Some of the survivors were sent to Truk in the Caroline Islands to form the 41st Guard Force. Another 150 were sent to Saipan in the Mariana Islands where most were killed in 1944 during the battle for the island.

At the time of the explosion Mutsu's magazine contained a number of 16-inch Type 3 "Sanshikidan" incendiary shells, which had caused a fire at the Sagami arsenal several years earlier due to improper storage. Because they might have been the cause of the explosion, the Minister of the Navy, Admiral Shimada Shigetaro, immediately ordered the removal of Type 3 shells from all IJN ships carrying them, until the conclusion of the investigation into the loss.

A gun from the Mutsu on display at the Yamato Museum in Kure, Japan

Investigations into the loss

An official accident commission led by Admiral Shiozawa Koichi was convened three days after the sinking to investigate the loss, with its preliminary conclusions issued on 25 June 1943. The commission considered a number of possible causes:

• Sabotage by enemy secret agents. Given the heavy security at the anchorage and lack of claims of responsibility by the Allies, this could be discounted.

• Sabotage by a disgruntled crewmen. While no individual was named in the commission’s final report, its conclusion was that the cause of the explosion was most likely a suicidal crewman in No. 3 turret who had recently been accused of theft.

• A midget or fleet submarine attack. Extensive searches immediately following the sinking had failed to detect any enemy submarine and the Allies had made no attempt at claiming the enormous propaganda value of sinking a capital ship in her home anchorage; consequently, this possibility was quickly discounted. Eyewitnesses also spoke of a reddish-brown fireball which indicated a magazine explosion and was confirmed during exploration of the wreck by divers.

• Accidental explosion within a magazine. While the Mutsu carried a large number of projectiles, immediate suspicion focused on the Type 3 anti-aircraft shell as it had been suspected of causing a fire before the war at the Sagami arsenal. Known as a "sanshiki-dan" or “sankaidan” these were fired by the main armament and contained 900 to 1,200 25 mm diameter steel tubes (depending upon sources), each containing an incendiary charge. Tests were conducted at Kamegakubi Naval Proving Ground on several shells salvaged from No. 3 turret and on shells from the previous and succeeding manufacturing batches. Using a specially built model of the Mutsu’s No. 3 turret, the experiments were unable to induce the shells to explode under any perceived service or artificial service conditions.

• Fire. Compared with other nation’s warships in wartime service, Japanese battleships contained a large amount of peacetime inflammable materials including untreated bedding, wooden decking, wooden furniture and wooden sheathing (for insulation). When she had been modernised in the 1930s, some of the Mutsu’s electrical wiring may have dated from her original commissioning. While fire in the secure magazines was a very remote possibly, a fire in an area adjacent to the Number 3 magazine could have raised the temperature to a sufficient enough level to ignite the highly sensitive black-powder primer stored in the magazine and thus instigate the explosion.

Salvage operations

Divers were brought into the area to retrieve bodies and to assess the damage to the ship. Prior to diving on the wreck they were allowed to familiarize themselves onboard the Mutsu’s sister-ship, the Nagato.

Despite initial negative reports from the divers the leadership of the Japanese Navy gave serious consideration to raising the remains of the Mutsu and possibly rebuilding her. To this end a dive was made from dive-boat No 3746 and a Nishimura -type search and rescue and research submersible on 17 June. This 7-man vessel, with a nominal 1-hour oxygen supply, snagged on the wreck and the crew nearly suffocated after two hours submerged before they managed to free themselves. Because of this risk the remainder of the inspections of the wreck were carried out by divers. After two months of undersea investigation, the navy reached the conclusion that the ship could not be recovered.

On 1 September 1943 the Mutsu was formally removed from the Navy List. In July 1944 the oil-starved Japanese Navy conducted Operation “Take” (Bamboo) which recovered 580 tons of fuel from the wreck.

The US Navy inspected the wreck in 1947. In the early 1950s, the United States occupation administration formally returned the wreck to the Japanese government, which allowed further salvage operations to be undertaken. This led in 1953, to the 1.2-metre diameter chrysanthemum crest, which had adorned the ship’s bow, being raised and in 1963 one of the 5.5-inch (140 mm) casemate guns.

On 20 March 1970, the Fukada Salvage Company acquired the rights to the wreck and undertook salvage operations until 1978, when the operation ended with about 75% of the ship recovered. Operations commencing with the raising of the No. 4 turret in 1970, were witnessed by Captain Miyoshi's widow. No. 3 turret was raised intact in September 1971.

In 1995, it was declared by the Mutsu Memorial Museum that there would be no more salvage operations. The only significant portion of the ship that remains is a 35 metre long section running from the bridge structure to and including the No.1 turret area. The highest portion of the ship is 12 metres below the surface.

Pieces recovered over the years can be viewed at various museums, memorials and shrines in Japan:

• Many artefacts are displayed at the Mutsu Memorial Museum in Tôwa Chô. This is a successor to a local museum funded by the town of Suo-Oshima which opened in July 1970. To make room for a new road, this museum was moved in April 1994 to a new building.
• The fully restored No. 4 turret is on display at the former naval academy at Etajima.
• The left-side 16-inch (410mm) gun from No. 3 turret is displayed outside the Yamato Museum in Kure in Daiwa Park. This park also contains one of Mutsu’s 3.5 metre diameter propellers, a rudder and an anchor.
• One 16-inch (410mm) gun from No. 3 turret is on display at the Museum of Maritime Science, Shinagawa, in Tokyo.
• One of the 5.5-inch (140 mm) secondary guns is displayed at Yasukuni Museum in Tokyo. This gun had been raised in 1963.
• A rudder and a section of propeller shaft were on display at the Arashiyama Art Museum until it closed c. 1991. Their current whereabouts are now unknown.

The pre-atomic age

Because her steel was created in the pre-atomic age and therefore does not contain large amounts of the radioactive isotopes which are present in modern steel, plates recovered from the Mutsu have been used in Japan in research facilities for radiation measuring and shielding purposes.

See also

• HMS Bulwark (1899)

Further reading

• Gardiner, Robert; Gray, Randal; Budzbon, Przemysław (1985). Conway's All the world's fighting ships, 1906–1921. London: Conway Maritime Press. pp. 416 pages. ISBN 0-85177-245-5.{{cite book}}: CS1 maint: multiple names: authors list (link)
• Stille, Mark (2008). Imperial Japanese Navy Battleships 1941–45. Oxford: Osprey Publishing. pp. 48 pages. ISBN 978-1-84603-280-6.
• Sturton, Eric, ed. (2008). Conway's Battleships. London: Conway Maritime Press. pp. 240 pages. ISBN 978-1-59114-132-7.
• Williams, Mike (2009). Jordan, John (ed.). Mutsu – An Exploration of the Circumstances Surrounding her Loss. Warship 2009. London: Conway. pp. 125–142. ISBN 978-1-84486-089-0.

External links

• Maritimequest.com: Mutsu photo gallery
• Tabular record of movement from combinedfleet.com