The two Nagato-class super-dreadnought were launched during the First World War and completed just after it. The sisterships were named Nagato and Mutsu, and they were the largest battleships in the Imperial Japanese Navy until the Yamato-class super battleships entered service.
Before and during the First World War the Imperial Japanese and Royal Navies retained official and unofficial links, and it is hardly surprising that the design of the Nagatos was heavily influenced by that of the Queen Elizabeth-class battleships. This can be seen by comparing the silhouettes of both classes of ships as built:
The Queen Elizabeth-class as built.
The Nagato-class as designed. They were completed with a hexapod foremast (see below).
The Nagato-class as built. The hexapod foremast can clearly be seen in this photograph.
The Nagato-class as built.
The class's characteristics as built were:
- Displacement: 32,200 tons (deep load)
- Dimensions:
- Length: 215.86m (708ft)
- Beam: 29.02m (95ft 3in)
- Draught: 9.08m (29ft 9in)
- Propulsion: 21 x Kampon water-tube boilers providing steam to 4 x Gihon steam turbines, each driving a propellor
- Speed: 26.5 knots
- Range: 4,500 nautical miles at 16 knots
- Complement: 1,333
- Armament: 4 × twin 410mm (16-inch) guns; 20 x single 140mm (5.5-inch) guns; 4 x single 76.2mm (3-inch) anti-aircraft guns; 8 × 533mm (21-inch) torpedo tubes
- Armour: Belt: 100mm to 305mm (3.9-inch to 12-inch); Deck: 69mm (2.7-inch) plus 75 mm (3-inch; Gun turrets: 190mm to 356mm (7.5-inch to 14-inch); Barbettes: 305mm (12-inch); Conning tower: 369mm (14.5-inch)
During their service they were rebuilt/reconstructed several times.
1924-25:
- The fore funnel was rebuilt into an S shape to prevent smoke interference.
The silhouette of the Nagato-class with their remodelled fore funnel.
The remodelled S-shaped funnel fitted to the Nagato-class battleships can be clearly be seen in this photograph.
1926:
- The four above-water torpedo tubes were removed, and the anti-aircraft armament was reinforced by three additional 3-inch/76mm anti-aircraft guns.
1932:
- The 3-inch/76mm anti-aircraft guns were removed and replaced by eight 5-inch/127mm in four twin dual-purpose mountings.
- The existing rangefinders fitted to the two superfiring main gun turrets were replaced by new 10m ones.
1933:
- A catapult was fitted between the mainmast and X turret and storage and maintenance facilities for 2 or 3 floatplanes was installed.
1934 to 1936:
- The bow was remodelled to reduce spray when steaming into a head sea.
- The stern was lengthened by 7.55 meters to improve speed.
- The forward superstructure was rebuilt into a pagoda mast.
- Torpedo bulges were added for better underwater protection.
- The main battery's elevation was increased to 43 degrees for improved range.
- The number of casemate-mounted 5.5-inch/140mm guns was reduced from eighteen to fourteen and their elevation was increased to 35 degrees for improved range.
- Twelve twin-mounted 1-inch/25mm Hotchkiss anti-aircraft machine guns were fitted.
- Additional armour was added to gun turrets and barbettes, increasing the ship's overall armour protection.
- The existing twenty-one mixed coal-fired and oil-fired water-tube Kampon boilers were replaced by ten lighter and more powerful oil-fired Kampon boilers.
- The fore funnel was removed and the remaining funnel was rebuilt in a different position.
- Newer, lighter steam turbines were fitted in place of the original geared turbines.
The silhouette of the Nagato-class after they were reconstructed in the mid-1930s.
1938:
- A new, much more powerful catapult was installed.
By 1944:
- Nagato: Additional 1-inch/25mm Hotchkiss anti-aircraft machine guns in twin and triple mountings were fitted to the IJNS Nagato, bringing her total to 98 barrels.
By 1945:
- Nagato: All the of casemate-mounted 5.5-inch/140mm guns were removed and two twin 5-inch/127mm in four twin dual-purpose mountings were added.
After their reconstruction, the class's characteristics were:
- Displacement: 38.510 tons (deep load)
- Dimensions:
- Length: 224.94m (738ft)
- Beam: 34.6m (113ft 6in)
- Draught: 9.49m (31ft 2in)
- Propulsion: 10 x Kampon oil-fired boilers providing steam to 4 x Gihon steam turbines, each driving a propellor
- Speed: 25 knots
- Range: 8.650 nautical miles at 16 knots
- Complement: 1,734
- Armament: 4 × twin 410mm (16-inch) guns; 18 x single 140mm (5.5-inch) guns; 4 x twin 127mm (5-inch) anti-aircraft guns; Up to 98 x 25mm anti-aircraft guns
- Armour: Belt: 100mm to 305mm (3.9-inch to 12-inch); Deck: 69mm (2.7-inch) plus 100 mm (3.9-inch; Gun turrets: 280mm to 460mm (11-inch to 18.1-inch); Barbettes: 457mm (18-inch)
- Aircraft: 3 x floatplanes; 1 x catapult
Nagato's wartime service:
- December 1941: Formed part of the distant force covering the retirement of the aircraft carrier that attacked Pearl Harbour.
- June 1942: Battle of Midway.
- June 1944: Battle of the Philippines Sea.
- October 1944: Battle of Leyte Gulf.
- October 1944: Battle of Sibuyan Sea.
- November 1944: Due to a shortage of fuel, she was reduced to the role of a floating anti-aircraft battery. Her mainmast and funnel were removed to improve the arcs-of-fire of the ship's anti-aircraft guns.
- July 1945: Badly damaged by an attack by US carrier-borne aircraft whilst at anchor.
- Post-war: Used as a target during the Bikini Atoll nuclear weapon test.
The IJNS Nagato in 1944.
Mutsu's wartime service:
- December 1941: Formed part of the distant force covering the retirement of the aircraft carrier that attacked Pearl Harbour.
- June 1942: Battle of Midway.
- August 1942: Battle of the Eastern Solomons.
- June 1943: Destroyed by an explosion in the magazine of No.3 turret.





















