Japanese battleship Mutsu , named after Mutsu Province , was a dreadnought battleship built for the Imperial Japanese Navy ( IJN ) during the 1910s and the second ship of her class . She carried supplies for the survivors of the Great Kantō earthquake in 1923 . The ship was modernized in 1934 – 36 with improvements to her armor and machinery and a rebuilt superstructure in the pagoda mast style . Other than participating in the Battle of Midway and the Battle of the Eastern Solomons in 1942 , where she did not see any significant combat , the ship spent most of the first year of the Pacific War training . " Mutsu " returned to Japan in early 1943 and one of her aft magazine s detonated in June while she was at anchor with the loss of 1 , 121 crew and visitors . The IJN conducted a perfunctory investigation into the cause of her loss and concluded that it was the work of a disgruntled crewmember . They dispersed the survivors in an attempt to conceal the sinking to keep up morale in Japan . Much of the wreck was salvaged after the war and many artifacts and relics are on display in Japan . Description . The ship had a length of between perpendiculars and overall . She had a beam of and a draft of . " Mutsu " displaced at standard load and at full load . Her crew consisted of 1 , 333 officers and enlisted men as built and 1 , 368 in 1935 . During World War II , the crew totaled around 1 , 475 men in 1942 . In 1927 , " Mutsu " s bow was remodeled to reduce the amount of spray produced when steaming into a head sea . This increased her overall length by to . During her 1934 – 36 reconstruction , the ship ' s stern was lengthened by to improve her speed and her forward superstructure was rebuilt into a pagoda mast . She was given torpedo bulge s to improve her underwater protection and to compensate for the weight of the additional armor and equipment . These changes increased her overall length to , her beam to and her draft to . Her displacement increased over to at deep load . Propulsion . " Mutsu " was equipped with four Gihon geared steam turbines , each of which drove one propeller shaft . The turbines were designed to produce a total of , using steam provided by 21 Kampon water - tube boilers ; 15 of these were oil - fired while the remaining half - dozen consumed a mixture of coal and oil . The ship had a stowage capacity of of coal and of fuel oil , giving her a range of at a speed of . The ship exceeded her designed speed of during her sea trials , reaching at . During a refit in 1924 the fore funnel was rebuilt in a serpentine shape in an unsuccessful effort to prevent smoke interference with the bridge and fire - control system s . That funnel was eliminated during the ship ' s 1930s reconstruction when her boilers were replaced by ten oil - fired Kampon boilers , which had a working pressure of and temperature of . In addition her turbines were replaced by lighter , more modern , units . When " Mutsu " conducted her post - reconstruction trials , she reached a speed of with . Additional fuel oil was stored in the bottoms of the newly added torpedo bulges , which increased her capacity to and thus her range to at 16 knots . Armament . " Mutsu " s eight 45 - caliber 41 - centimeter guns were mounted in two pairs of twin - gun , superfiring turrets fore and aft . Numbered one through four from front to rear , the hydraulically powered turrets gave the guns an elevation range of −2 to + 35 degrees . The rate of fire for the guns was around two rounds per minute . A special Type 3 " Sankaidan " incendiary shrapnel shell was developed in the 1930s for anti - aircraft use . The turrets aboard the " Nagato " - class ships were replaced in the mid - 1930s using the turrets stored from the unfinished s . While in storage the turrets were modified to increase their range of elevation to – 3 degrees to + 43 degrees , which increased the guns maximum range from . The ship ' s secondary armament of twenty 50 - caliber 14 - centimeter guns was mounted in casemate s on the upper sides of the hull and in the superstructure . The manually operated guns had a maximum range of and fired at a rate of six to 10 rounds per minute . Anti - aircraft defense was provided by four 40 - caliber 8 - centimeter 3rd Year Type AA gun s in single mounts . The high - angle guns had a maximum elevation of + 75 degrees , and had a rate of 13 to 20 rounds per minute . The ship was also fitted with eight torpedo tube s , four on each broadside , two above water and two submerged . Around 1926 , the four above - water torpedo tubes were removed and the ship received three additional 76 mm AA guns that were situated around the base of the foremast . The 76 mm AA guns were replaced by eight 40 - caliber 127 - millimeter dual - purpose gun s in 1932 , fitted on both sides of the fore and aft superstructures in four twin - gun mounts . When firing at surface targets , the guns had a range of ; they had a maximum ceiling of at their maximum elevation of + 90 degrees . Their maximum rate of fire was 14 rounds a minute , but their sustained rate of fire was around eight rounds per minute . Two twin - gun mounts for license - built Vickers two - pounder light AA guns were also added to the ship that same year . These guns had a maximum elevation of + 80 degrees which gave them a ceiling of . They had a maximum rate of fire of 200 rounds per minute . The unsatisfactory two - pounders were replaced by 1941 by twenty license - built Hotchkiss 25 mm Type 96 light AA guns in five twin - gun mounts . This was the standard Japanese light AA gun during World War II , but it suffered from severe design shortcomings that rendered it a largely ineffective weapon . According to historian Mark Stille , the twin and triple mounts " lacked sufficient speed in train or elevation ; the gun sights were unable to handle fast targets ; the gun exhibited excessive vibration ; the magazine was too small , and , finally , the gun produced excessive muzzle blast " . These guns had an effective range of , and an effective ceiling of at an elevation of 85 degrees . The maximum effective rate of fire was only between 110 and 120 rounds per minute because of the frequent need to change the fifteen - round magazines . Armor . The ship ' s waterline armor belt was thick and tapered to a thickness of at its bottom edge ; above it was a strake of armor . The main deck armor was while the lower deck was thick . The turrets were protected with an armor thickness of 305 mm on the face , on the sides , and on the roof . The barbette s of the turrets were protected by armor 305 mm thick , while the casemates of the 140 mm guns were protected by 25 mm armor plates . The sides of the conning tower were thick . The new 41 cm turrets installed during " Mutsu " s reconstruction were more heavily armored than the original ones . Face armor was increased to , the sides to , and the roof to . The armor over the machinery and magazines was increased by 38 mm on the upper deck and 25 mm on the upper armored deck . These additions increased the weight of the ship ' s armor to , 32 . 6 percent of her displacement . In early 1941 , in preparation for war , " Mutsu " s barbette armor was reinforced with armor plates above the main deck and plates below it . Aircraft . " Mutsu " had an additional boom added to the mainmast in 1926 to handle the Yokosuka E1Y floatplane recently assigned to the ship . In 1933 a catapult was fitted between the mainmast and Turret No . 3 , and a collapsible crane was installed in a portside sponson the following year ; the ship was equipped to operate two or three floatplanes , although no hangar was provided . The ship was operating Nakajima E4N2 biplanes until they were replaced by Nakajima E8N2 biplanes in 1938 . A more powerful catapult was installed in November 1938 to handle heavier aircraft like the single Kawanishi E7K , added in 1939 – 40 . Mitsubishi F1M biplanes replaced the E8Ns on 11 February 1943 . Fire control and sensors . The ship was fitted with a rangefinder in the forward superstructure . Additional and anti - aircraft rangefinders were also fitted , although the date is unknown . The rangefinders in No . 2 and 3 Turrets were replaced by 10 - meter units in 1932 – 33 . " Mutsu " was initially fitted with a Type 13 fire - control system derived from Vickers equipment received during World War I , but this was replaced by an improved Type 14 system around 1925 . It controlled the main and secondary guns ; no provision was made for anti - aircraft fire until the Type 31 fire - control director was introduced in 1932 . A modified Type 14 fire - control system was tested aboard " Nagato " in 1935 and later approved for service as the Type 94 . A new anti - aircraft director , the Type 94 used to control the 127 mm AA guns , was introduced in 1937 , although when " Mutsu " received hers is unknown . The 25 mm AA guns were controlled by a Type 95 director that was also introduced in 1937 . Construction and service . " Mutsu " , named for Mutsu Province , and for the Meiji Emperor ' s personal name , Mutsuhito , was laid down at the Yokosuka Naval Arsenal on 1 June 1918 and launched on 31 May 1920 . Funding for the ship had partly come from donations from schoolchildren . She was commissioned on 24 October 1921 with Captain Shizen Komaki in command . The ship was assigned to the 1st Battleship Division on 1 December after Captain Seiichi Kurose assumed command on 18 November . " Mutsu " hosted Edward , Prince of Wales , and his aide - de - camp Lieutenant Louis Mountbatten on 12 April 1922 during the prince ' s visit to Japan . After the 1923 Great Kantō earthquake , " Mutsu " loaded supplies at Uchinoura Bay , Kyushu for the victims on 4 September . Together with her sister ship , she sank the hulk of the obsolete battleship on 7 September 1924 during gunnery practice in Tokyo Bay in accordance with the Washington Naval Treaty . Captain Mitsumasa Yonai , later Prime Minister of Japan , assumed command on 10 November . The ship was transferred to the reserve on 1 December 1925 . " Mutsu " served as flagship of Emperor Hirohito during the 1927 naval maneuvers and fleet review . On 10 December 1928 , Captain Zengo Yoshida relieved Captain Teikichi Hori . On 29 March 1929 , the ship was assigned to Battleship Division 3 , together with three light cruiser s . " Mutsu " s anti - aircraft armament was upgraded during 1932 . Upon completion , she was assigned to Battleship Division 1 of the 1st Fleet and again served as the Emperor ' s flagship during the annual maneuvers and fleet review in 1933 . The ship was placed in reserve on 15 November and began her lengthy reconstruction . This was completed on 30 September 1936 and " Mutsu " rejoined the 1st Battleship Division on 1 December 1936 . In August 1937 , she transported 2 , 000 men of the 11th Infantry Division to Shanghai during the Second Sino - Japanese War . Her floatplanes bombed targets in Shanghai on 24 August before she returned to Sasebo the following day . On 15 November 1938 , Captain Aritomo Gotō assumed command of the ship . The ship was placed in reserve 15 December 1938 – 15 November 1939 . She was refitted in early 1941 in preparation for war , which included fitting of external degaussing coils and additional armor for her barbettes . World War II . During the war " Mutsu " saw limited action , spending much of her time in home waters . When the war started for Japan on 8 December , she sortie d for the Bonin Islands , along with " Nagato " , the battleships , , , of Battleship Division 2 , and the light carrier as distant support for the fleet attacking Pearl Harbor , and returned six days later . On 18 January 1942 , " Mutsu " towed the obsolete armored cruiser as a target for the new battleship , which promptly sank her . In June 1942 " Mutsu " , commanded by Rear Admiral Gunji Kogure , was assigned to the Main Body of the 1st Fleet during the Battle of Midway , together with " Yamato " , " Nagato " , " Hosho " , the light cruiser " Sendai " , nine destroyers and four auxiliary ships . Following the loss of all four carriers on 4 June , Yamamoto attempted to lure the American forces west to within range of the Japanese air groups at Wake Island , and into a night engagement with his surface forces , but the American forces withdrew and " Mutsu " saw no action . After rendezvousing with the remnants of the Striking Force on 6 June , about half of the survivors from the sunken aircraft carriers of the 1st Air Fleet were transferred to " Mutsu " . She arrived at Hashirajima on 14 June . On 14 July " Mutsu " was transferred to Battleship Division 2 and then to the Advance Force of the 2nd Fleet on 9 August . Two days later , the ship departed Yokosuka accompanied by the cruisers , , , , , , the seaplane tender and escorting destroyers to support operations during the Guadalcanal Campaign . They arrived at Truk on 17 August . On 20 August , while sailing from Truk to rendezvous with the main body of Vice Admiral Chūichi Nagumo ' s 3rd Fleet , " Mutsu " , the heavy cruiser " Atago " , and escorting destroyers unsuccessfully attempted to locate the escort carrier in response to a flying boat detecting the American ship . During the Battle of the Eastern Solomons on 27 August , " Mutsu " , assigned to the Support Force , fired four shells at enemy reconnaissance aircraft during what was her first and only action of the war . Following her return to Truk on 2 September , a group of skilled AA gunnery officers and men were detached to serve as instructors to ground - based naval anti - aircraft gunners stationed in Rabaul . During October " Mutsu " off - loaded surplus fuel oil to the fleet oil tanker " Kenyo Maru " which allowed the tanker to refuel other ships involved in Guadalcanal operations . On 7 January 1943 , " Mutsu " steamed from Truk via Saipan to return to Japan together with the carrier , the heavy cruiser and four destroyers . The ship left Hashirajima for Kure on 13 April , where she prepared to sortie to reinforce the Japanese garrisons in the Aleutian Islands in response to the Battle of the Komandorski Islands . The operation was cancelled the next day and " Mutsu " resumed training . Loss . On 8 June 1943 , " Mutsu " was moored in the Hashirajima fleet anchorage , with 113 flying cadet s and 40 instructors from the Tsuchiura Naval Air Group aboard for familiarization . At 12 : 13 the magazine of her No . 3 turret exploded , destroying the adjacent structure of the ship and cutting her in half . A massive influx of water into the machinery spaces caused the forward section of the ship to capsize to starboard and sink almost immediately . The stern section upended and remained floating until about 02 : 00 hours on 9 June before sinking , coming to rest a few hundred feet south of the main wreck at coordinates . The nearby " Fusō " immediately launched two boats which , together with the destroyers and and the cruisers and , were able to rescue 353 survivors from the 1 , 474 crew members and visitors aboard " Mutsu " ; 1 , 121 men were killed in the explosion . Only 13 of the visiting aviators were among the survivors . After the explosion , as the rescue operations commenced , the fleet was alerted and the area was searched for Allied submarines , but no traces were found . To avert the potential damage to morale from 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 Teruhiko Miyoshi ' s body was recovered by divers on 17 June , but his wife was not officially notified until 6 January 1944 . Both he and his second in command , Captain Ono Koro , were posthumously promoted to Rear Admiral , as was normal practice . To further prevent rumors 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 and assigned to 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 shrapnel 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 . Investigation into the loss . A commission led by Admiral Kōichi Shiozawa was convened three days after the sinking to investigate the loss . The commission considered a number of possible causes : The commission issued its preliminary conclusions on 25 June , well before the divers had completed their investigation of the wreck , and concluded that the explosion was the result of a disgruntled seaman . Historian Mike Williams put forward an alternative theory : 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 on board " Mutsu " s sister ship , " Nagato " . The Navy leadership initially gave serious consideration to raising the wreck and rebuilding her , although these plans were dropped after the divers completed their survey of the ship on 22 July . Thus " Mutsu " was struck from the Navy List on 1 September . As part of the investigation , Dive - boat No . 3746 , a small " Nishimura " - class search and rescue submarine , dove on the wreck on 17 June with a crew of seven officers . While crawling on the harbor bottom , it became snagged on the wreckage and its crew nearly suffocated before they managed to free themselves and surface . In July 1944 , the oil - starved IJN recovered of fuel from the wreck . In the early 1950s , the US occupation administration returned the wreck to the Japanese government . The diameter chrysanthemum crest , symbol of the Imperial Throne , was raised in 1953 , and one of the 140 mm casemate guns was raised in 1963 and donated to the Yasukuni Shrine . In 1970 , the Fukada Salvage Company began salvage operations that lasted until 1978 and recovered about 75 % of the ship . The two aft turrets were raised in 1970 and 1971 . The salvagers recovered 849 bodies of crewmen lost during the explosion . In 1995 , the Mutsu Memorial Museum declared that no further salvage operations were planned . The only significant portion of the ship that remains is a long section running from the bridge structure forward to the vicinity of No . 1 turret . The highest portion of the ship is below the surface . Surviving artifacts . Pieces recovered over the years can be viewed at various museums and memorials in Japan :