was a super-dreadnought battleship built for the Imperial Japanese Navy (IJN). Completed in 1920 as the lead ship of her class, she carried supplies for the survivors of the Great Kantō earthquake in 1923. The ship was modernized in 1934–1936 with improvements to her armor and machinery and a rebuilt superstructure in the pagoda mast style. Nagato briefly participated in the Second Sino-Japanese War in 1937 and was the flagship of Admiral Isoroku Yamamoto during the attack on Pearl Harbor. She covered the withdrawal of the attacking ships and did not participate in the attack itself.
Other than participating in the Battle of Midway in June 1942, where she did not see combat, the ship spent most of the first two years of the Pacific War training in home waters. She was transferred to Truk in mid-1943, but did not see any combat until the Battle of the Philippine Sea in mid-1944 when she was attacked by American aircraft. Nagato did not fire her main armament against enemy vessels until the Battle of Leyte Gulf in October. She was lightly damaged during the battle and returned to Japan the following month. The IJN was running out of fuel by this time and decided not to fully repair her. Nagato was converted into a floating anti-aircraft platform and assigned to coastal defense duties. She was attacked in July 1945 as part of the American campaign to destroy the IJN's last remaining capital ships, but was only slightly damaged and went on to be the only Japanese battleship to have survived World War II. In mid-1946, the ship was a target for nuclear weapon tests during Operation Crossroads. She survived the first test with little damage, but was sunk by the second.
Description Nagato had a length of between perpendiculars and overall. She had a beam of and a draft of .Skwiot 2008, p. 4 The ship displaced at standard load and at full load.Whitley, p. 200 Her crew consisted of 1,333 officers and enlisted men as built and 1,368 in 1935.Jentschura, Jung & Mickel, p. 28 The crew totaled around 1,734 men in 1944.Stille, p. 34
In 1930,Skwiot 2007, p. 34 Nagatos 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 1934–1936 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 bulges 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. The ship's metacentric height at deep load was .Skwiot 2008, pp. 6, 9–10, 71 In November 1944, the tops of Nagatos mainmast and funnel were removed to improve the effective arcs of fire for her anti-aircraft guns.
Propulsion
Nagato 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 could carry 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 .
Funnel smoke would often choke and blind crewmen on the bridge and in the fire-control systems so a "fingernail"-shaped deflector was installed on the fore funnel in 1922 to direct the exhaust away from them. It was less than effective and the fore funnel was rebuilt in a serpentine shape in an unsuccessful effort during a refit in 1924. That funnel was eliminated during the ship's 1930s reconstruction when all of her boilers were replaced by ten oil-fired Kampon boilers, which had a working pressure of and temperature of .Skwiot 2008, pp. 73, 76–77 In addition her turbines were replaced by lighter, more modern, units. When Nagato conducted her post-reconstruction trials, she reached a speed of with .Skwiot 2008, p. 78 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
Nagatos eight 45-caliber 41-centimeter (16 inch) 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. The turrets aboard the Nagato-class ships were replaced in the mid-1930s with the turrets stored from the unfinished s. While in storage the turrets had been modified to increase their range of elevation to –3 to +43 degrees,Skwiot 2008, p. 19 which increased the gun's maximum range from .Friedman, p. 269
The ship's secondary armament of twenty 50-caliber 14-centimeter guns was mounted in casemates 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.Skwiot 2008, p. 24 Anti-aircraft defense was provided by four 40-caliber 3rd Year Type three-inch AA guns in single mounts. The high-angle guns had a maximum elevation of +75 degrees, and had a rate of fire of 13 to 20 rounds per minute.Campbell, p. 198 The ship was also fitted with eight torpedo tubes, four on each broadside, two above water and two submerged.Skwiot 2008, p. 31
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.Skwiot 2008, p. 70 They were replaced by eight 40-caliber 12.7-centimeter Type 89 dual-purpose (DP) guns in 1932, fitted on both sides of the fore and aft superstructures in four twin-gun mounts.Whitley, p. 202 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.Campbell, pp. 192–193 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 .Skwiot 2008, pp. 26, 30 They had a maximum rate of fire of 200 rounds per minute.Campbell, p. 200
When the ship was reconstructed in 1934–1936, the remaining torpedo tubes and the two forward 14 cm (-inch) guns were removed from the hull. The remaining 14 cm guns had their elevation increased to +35 degrees which increased their range to . An unknown number of license-built Hotchkiss M1929 machine gun in twin mounts were added. The maximum range of these guns was ,Skwiot 2008, pp. 33, 72–73 but the effective range against aircraft was . The cyclic rate was adjustable between 425 and 475 rounds per minute, but the need to change 30-round magazines reduced the effective rate to 250 rounds per minute.Campbell, p. 202
The unsatisfactory two-pounders were replaced in 1939 by twenty license-built Type 96 Hotchkiss Type 96 light AA guns in a mixture of twin-gun and single 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".Stille, p. 11 These 25 mm 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. Additional Type 96 guns were installed during the war; on 10 July 1944, the ship was reported to have 98 guns on board. An additional 30 guns were added during a refit in Yokosuka in November. Two more twin 12.7 cm (5 inch) gun mounts were added at the same time abreast the funnelSkwiot 2008, p. 80 and her 14 cm guns were removed as she was by then a floating anti-aircraft battery.
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.Skwiot 2008, pp. 10–11 The turrets were protected with an armor thickness of 305 mm on the face, on the sides, and on the roof. The barbettes of the turrets were protected by armor 305 mm thick, while the casemates of the 1 guns were protected by armor plates. The sides of the conning tower were thick.Whitley, p. 200
The new 41 cm turrets installed during Nagatos reconstruction were more heavily armored than the original ones. Face armor was increased to , the sides to , and the roof to .Campbell, p. 182 The armor over the machinery and magazines was increased by 38 mm on the upper deck and on the upper armored deck. These additions increased the weight of the ship's armor to , 32.6 percent of her displacement.Stille, p. 32 In early 1941, as a preparation for war, Nagatos barbette armor was reinforced with armor plates above the main deck and plates below it.Chesneau, p. 172
Fire control and sensors When completed in 1920, the ship was fitted with a rangefinder in the forward superstructure; and anti-aircraft rangefinders were added in May 1921 and 1923, respectively. The rangefinders in the second and third turrets were replaced by 10-meter units in 1932–1933.Skwiot 2008, pp. 34, 72
Nagato 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 the ship in 1935 and later approved for service as the Type 34. A new anti-aircraft director called the Type 94 that was used to control the 127 mm AA guns was introduced in 1937, although when Nagato received hers is unknown. The Type 96 AA guns were controlled by a Type 95 director that was also introduced in 1937.Skwiot 2008, pp. 33–37, 72
While in drydock in May 1943, a Type 21 air search radar was installed on the roof of the 10-meter rangefinder at the top of the pagoda mast. On 27 June 1944, two Type 22 surface search radars were installed on the pagoda mast and two Type 13 early warning radars were fitted on her mainmast.
Aircraft Nagato was fitted with an Skwiot 2008, p. 47 aircraft flying-off platform on Turret No. 2 in August 1925. Yokosuka Ro-go Ko-gata and Heinkel HD 25 floatplanes were tested from it before it was removed early the following year. An additional boom was added to the mainmast in 1926 to handle the Yokosuka E1Y now assigned to the ship. A Hansa-Brandenburg W.33 floatplane was tested aboard Nagato that same year. A catapult was fitted between the mainmast and Turret No. 3Skwiot 2008, p. 57 in mid-1933,Hackett, Kingsepp, & Ahlberg a collapsible crane was installed in a portside sponson, and the ship was equipped to operate two or three floatplanes, although no hangar was provided. The ship now operated 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, such as the one Kawanishi E7K that was added in 1939–1940. Mitsubishi F1M biplanes replaced the E8Ns on 11 February 1943.Skwiot 2008, pp. 54, 57
Construction and career