# Nagato-class battleship
The **Nagato class** (長門型戦艦) was a class of two super-dreadnought battleships of the [Imperial Japanese Navy](https://www.edgepedia.org/imperial-japanese-navy), *Nagato* and *Mutsu*, built in the late 1910s as the first warships in the world to carry 16-inch (41 cm) main guns.[1](https://www.usni.org/magazines/naval-history-magazine/1998/october/sea-nagato) Completed in November 1920 and October 1921, they were Japan's most modern capital ships throughout the interwar period and *Nagato* the only Imperial Japanese Navy battleship to survive the Second World War.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) • [3](https://www.ospreypublishing.com/us/nagatoclass-battleships-192046-9781472869555/)
| Key fact | Detail |
|---|---|
| Ships | *Nagato* (laid down 28 August 1917, completed November 1920) and *Mutsu* (laid down June 1918, completed October 1921)[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) • [4](https://naval-encyclopedia.com/ww2/japan/nagato-class-battleships.php) |
| Displacement | 33,800 tons standard as built; 39,120 tons standard after the 1934-36 modernization[5](https://www.globalsecurity.org/military/world/japan/nagato-bb-specs.htm) |
| Speed | 80,000 shp geared turbines, 26.5 knots designed; *Nagato* made 26.443 knots on trials, a record for a battleship[6](https://www.combinedfleet.com/nagatrom.htm) |
| Designer | Captain (later Vice Admiral) Yuzuru Hiraga, under project design A-102, with a distinctive hexapod pagoda mast[4](https://naval-encyclopedia.com/ww2/japan/nagato-class-battleships.php) |
| Wartime role | Flagship of the Combined Fleet under Admiral Yamamoto Isoroku at the Pearl Harbor attack; main guns fired in action only at the Battle of Samar, October 1944[1](https://www.usni.org/magazines/naval-history-magazine/1998/october/sea-nagato) • [2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) |
| Fates | *Mutsu* sunk by an internal magazine explosion in June 1943 with 1,121 dead; *Nagato* sunk in the 1946 Operation Crossroads atomic tests at Bikini Atoll[7](https://www.oldtokyo.com/eight-eight-fleet-program-imperial-japanese-navy-c-1925/) • [3](https://www.ospreypublishing.com/us/nagatoclass-battleships-192046-9781472869555/) |
## Design and construction
The class emerged from Japan's "Eight-Eight" fleet program, conceived in 1907, which called for eight modern battleships and eight battlecruisers.[7](https://www.oldtokyo.com/eight-eight-fleet-program-imperial-japanese-navy-c-1925/) The design work was done largely in Japan, a departure from earlier practice in which the first eight IJN battleships and the lead ship of the Kongo class had been designed and built in Great Britain.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) Captain Yuzuru Hiraga of the Navy Technical Department developed the design through a series of proposals after the [Battle of Jutland](https://www.edgepedia.org/battle-of-jutland) (31 May to 1 June 1916); the preliminary studies moved toward an all-or-nothing armor scheme with a 305 mm belt, a 70 mm main deck, and 76 mm slopes, values close to the ship as built.[8](https://warshipprojects.com/2023/03/07/development-of-the-nagato-class/)
**Armament and speed.** The Nagatos carried eight 41 cm/45-caliber guns in four two-gun turrets, two superfiring pairs fore and aft. A full broadside weighed 17,520 pounds, heavier than that of the contemporary American *Maryland* (16,800 pounds) or the British *Queen Elizabeth* and *Hood* (15,360 pounds).[9](https://www.usni.org/magazines/proceedings/1922/january/professional-notes) All-geared turbine engines producing 80,000 shp gave a designed speed of 26.5 knots, two knots faster than the Queen Elizabeth class they were meant to supersede; the IJN prioritized speed over protection, in contrast to the 21-knot USN standard battleships.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) During speed trials *Nagato* beat the world record for a battleship, making 26.443 knots.[6](https://www.combinedfleet.com/nagatrom.htm) The most arresting external feature was the foremast, a central trunk supported by six struts, the hexapod pagoda mast unique to this class.[9](https://www.usni.org/magazines/proceedings/1922/january/professional-notes) • [4](https://naval-encyclopedia.com/ww2/japan/nagato-class-battleships.php)
The Japanese attempted to incorporate the lessons of Jutland, but construction had already progressed too far for this to be fully practical; deck armor was strengthened and protection against flash fires in the barbettes was improved.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/)
## The Washington Treaty and interwar service
The Washington Naval Conference of November 1921 to February 1922 ended the naval arms race and imposed a battleship building holiday, so that the Nagatos and the American Colorados remained the most modern battleships in their fleets until capital ship construction resumed in 1937.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) Under the treaty, all Japanese ships started after *Nagato* had to be broken up or converted into aircraft carriers, but a special exemption saved *Mutsu*, which was nearing completion and had a special place in Japanese public affection, with much of her construction funded by public subscription.[7](https://www.oldtokyo.com/eight-eight-fleet-program-imperial-japanese-navy-c-1925/) Her retention caused consternation at the conference, since the other signatories had to scrap new or building capital ships of their own.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/)
The two ships alternated as flagships of the [Combined Fleet](https://www.edgepedia.org/combined-fleet), and the pre-war phrase "Mutsu to Nagato wa Nihon no hokori" (Mutsu and Nagato are Japan's pride) captured their standing.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) Between 1934 and 1936 both were heavily modernized: the stern was lengthened, the forward superstructure rebuilt as a full pagoda mast, torpedo bulges and additional vertical armor added, and displacement rose by about 7,000 metric tons to 39,120 tons standard, while speed fell to about 25 knots.[8](https://warshipprojects.com/2023/03/07/development-of-the-nagato-class/) • [10](https://naval-encyclopedia.com/ww2/japan/battleships.php) Main turret elevation increased from 30 degrees to 43 degrees, extending maximum gun range from 32,500 m to 38,300 m.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/)
## Second World War
*Nagato* flew the flag of Admiral Isoroku Yamamoto, Commander-in-Chief of the Combined Fleet.
**Limited employment.** Except for the Kongo class, the IJN held its battleships back for a decisive fleet battle that never came. Both ships were present at Midway in June 1942 and *Nagato* at the [Philippine Sea](https://www.edgepedia.org/philippine-sea) in June 1944, but neither played a noteworthy role in either encounter.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) *Mutsu* was destroyed in June 1943 when a magazine explosion broke the ship in two while she lay moored at the Hashirajima fleet anchorage, killing 1,121 sailors; no official acknowledgement of the loss was made until after the war.[7](https://www.oldtokyo.com/eight-eight-fleet-program-imperial-japanese-navy-c-1925/)
At the [Battle of Leyte Gulf](https://www.edgepedia.org/battle-of-leyte-gulf) (23 to 26 October 1944), *Nagato* served in Vice Admiral Kurita's force alongside *Yamato*, *Musashi*, *Kongo*, and *Haruna*.[11](https://www.history.navy.mil/about-us/leadership/director/directors-corner/h-grams/h-gram-038/h-038-2.html) At the Battle of Samar she fired forty-five main-armament armor-piercing rounds, the only time either ship of the class ever fired at enemy ships, and the fewest of the four IJN battleships engaged.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) She was hit by two bombs at [Leyte Gulf](https://www.edgepedia.org/leyte-gulf), and later by another that passed through her bow and exploded in the water.[1](https://www.usni.org/magazines/naval-history-magazine/1998/october/sea-nagato) In mid-late 1944 her anti-aircraft fit was expanded to 119 barrels of 25 mm and 12.7 cm guns, and radar sets of Types 13, 21, and 22 were fitted.[8](https://warshipprojects.com/2023/03/07/development-of-the-nagato-class/)
By the beginning of 1945 *Nagato* was a battleship without a fleet and without oil, anchored off Yokosuka in [Tokyo Bay](https://www.edgepedia.org/tokyo-bay) with her mainmast and stack cut down for camouflage; she was hit once more by bombers there but survived, the only IJN battleship to do so.[1](https://www.usni.org/magazines/naval-history-magazine/1998/october/sea-nagato) • [3](https://www.ospreypublishing.com/us/nagatoclass-battleships-192046-9781472869555/)
## Operation Crossroads and the wreck
In 1946 the U.S. Navy took the derelict *Nagato* to Bikini Atoll for Operation Crossroads, the first postwar atomic bomb tests. She was moored 400 yards from the target ship USS Nevada for the Able air burst of 1 July 1946 and was moderately damaged; a ship's report concluded that "Nagato is structurally sound," her poor condition reflecting a year of idle machinery rather than blast damage.[12](https://www.npshistory.com/series/archeology/scrc/37/chap4.htm) The Baker underwater detonation of 25 July 1946 opened holes in her hull plating, and she sank in the lagoon.[12](https://www.npshistory.com/series/archeology/scrc/37/chap4.htm) A Bureau of Ships observer noted that, except for *Nagato*, the ships sunk at Bikini had been carrying loads greatly in excess of their design.[13](https://nsarchive.gwu.edu/document/21907-document-32-commander-e-h-batcheller-chief)
The wreck lies in Bikini Atoll Lagoon at a depth of about 170 feet and was surveyed by [National Park Service](https://www.edgepedia.org/national-park-service) divers in 1989 and 1990 as part of the submerged cultural resources assessment of the Crossroads fleet; the forward turrets remain intact with their rangefinders visible.[14](https://www.npshistory.com/series/archeology/scrc/37/chap1.htm) • [12](https://www.npshistory.com/series/archeology/scrc/37/chap4.htm)
## Assessment
The class combined the heaviest broadside afloat at completion with a speed advantage over every contemporary battleship, and the 1922 treaty freeze preserved that lead for fifteen years.[9](https://www.usni.org/magazines/proceedings/1922/january/professional-notes) • [2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/) In the event, the IJN's strategy of holding its battleships for a decisive battle meant the ships saw little combat: the historian-authors Hans Lengerer and Lars Ahlberg fault the poor strategic and tactical handling of both ships, noting that active participation in operations was extremely rare.[2](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/)
## References
1. [At Sea on the Nagato, Stuart M. Tave, Naval History Magazine, October 1998, U.S. Naval Institute](https://www.usni.org/magazines/naval-history-magazine/1998/october/sea-nagato)
2. [Nagato-Class Battleships: IJN Super-Dreadnoughts Nagato and Mutsu (review of Lengerer and Ahlberg), International Journal of Naval History](https://ijnh.seahistory.org/nagato-class-battleships-ijn-super-dreadnoughts-nagato-and-mutsu/)
3. [Nagato-class Battleships 1920-46, Stefan Draminski, Osprey Publishing](https://www.ospreypublishing.com/us/nagatoclass-battleships-192046-9781472869555/)
4. [Nagato class Battleships (1919), naval encyclopedia](https://naval-encyclopedia.com/ww2/japan/nagato-class-battleships.php)
5. [IJN Nagato Class Battleships, GlobalSecurity.org](https://www.globalsecurity.org/military/world/japan/nagato-bb-specs.htm)
6. [Imperial Battleships: Nagato, Combined Fleet](https://www.combinedfleet.com/nagatrom.htm)
7. ["Eight-Eight" Fleet Program, Imperial Japanese Navy, c. 1925, Old Tokyo](https://www.oldtokyo.com/eight-eight-fleet-program-imperial-japanese-navy-c-1925/)
8. [Development of the Nagato class, Warship Projects 1900-1950](https://warshipprojects.com/2023/03/07/development-of-the-nagato-class/)
9. [Professional Notes, Proceedings, January 1922, U.S. Naval Institute](https://www.usni.org/magazines/proceedings/1922/january/professional-notes)
10. [WW2 Japanese Battleships, naval encyclopedia](https://naval-encyclopedia.com/ww2/japan/battleships.php)
11. [H-038-2 Leyte Gulf in Detail, Naval History and Heritage Command](https://www.history.navy.mil/about-us/leadership/director/directors-corner/h-grams/h-gram-038/h-038-2.html)
12. [The Archeology of the Atomic Bomb, Chapter 4, National Park Service](https://www.npshistory.com/series/archeology/scrc/37/chap4.htm)
13. [Commander E. H. Batcheller to Chief of the Bureau of Ships, 14 October 1946, National Security Archive](https://nsarchive.gwu.edu/document/21907-document-32-commander-e-h-batcheller-chief)
14. [The Archeology of the Atomic Bomb, Chapter 1, National Park Service](https://www.npshistory.com/series/archeology/scrc/37/chap1.htm)
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