The were two battleships of the Imperial Japanese Navy, and . Their keels were laid down in 1937 and 1938, and they were commissioned as designed in 1941 and 1942. A third hull, laid down in 1940, was converted to the aircraft carrier during construction. Two further ships were planned but never constructed.
Displacing nearly at full load, the completed battleships were the heaviest ever constructed. The class carried the largest naval artillery ever fitted to a warship, nine 460 mm (18.1 in) naval guns, each capable of firing shells over .
Because of the threat of U.S. submarines and aircraft carriers, Yamato and Musashi spent the majority of their careers in naval bases at Brunei, Truk, and Kure, deploying on several occasions in response to U.S. raids on Japanese bases.
All three ships were sunk by the U.S. Navy, Musashi by air strikes while participating in the Battle of Leyte Gulf in October 1944, Shinano after being torpedoed by the submarine while under way from Yokosuka to Kure for fitting out in November 1944, and Yamato by air strikes while en route from Japan to Okinawa as part of Operation Ten-Go in April 1945.
Background The design of the Yamato-class battleships was shaped by expansionist movements within the Japanese government, Japanese industrial power, and the need for a fleet powerful enough to intimidate likely adversaries. Most importantly, the latter, in the form of the Kantai Kessen or Decisive Battle Doctrine, a naval strategy adopted by the Imperial Japanese Navy (IJN) prior to the Second World War, in which the Japanese navy would win a war by fighting and winning a single, decisive naval action.Stille (2014), p. 10
After the end of the First World War, many navies—including those of the United States, the United Kingdom, and Imperial Japan—continued and expanded construction programs that had begun during the conflict. The enormous costs associated with these programs pressured their government leaders to begin a disarmament conference. On 8 July 1921, the United States' Secretary of State Charles Evans Hughes invited delegations from the other major maritime powers—France, Italy, Japan, and the United Kingdom—to come to Washington, DC, and discuss a possible end to the naval arms race. The subsequent Washington Naval Conference resulted in the Washington Naval Treaty. Along with many other provisions, it limited all future battleships to a standard displacement of and a maximum gun caliber of . It also agreed that the five countries would not construct more capital ships for 10 years and would not replace any ship that survived the treaty until it was at least 20 years old.Friedman, p. 182Garzke and Dulin, pp. 4–5
In the 1930s, the Japanese government began a shift towards ultranationalist militancy.Willmott, p. 32 This movement called for the expansion of the Empire of Japan to include much of the Pacific Ocean and Southeast Asia. The maintenance of such an empire—spanning from China to Midway Island—required a sizable fleet capable of sustained control of territory.Schom, p. 42 Although all of Japan's battleships built prior to the Yamato class had been completed before 1921—as the Washington Treaty had prevented any more from being completed—all had been either reconstructed or significantly modernized, or both, in the 1930s.Willmott, p. 34; Gardiner and Gray, p. 229 This modernization included, among other things, additional speed and firepower, which the Japanese intended to use to conquer and defend their aspired-to empire.Gardiner and Gray, pp. 229–231, 234 When Japan withdrew from the League of Nations in 1934 over the Mukden Incident, it also renounced all treaty obligations,Garzke and Dulin, p. 44 freeing it to build warships larger than those of the other major maritime powers.Willmott, p. 35
Japan's intention to acquire resource-producing colonies in the Pacific and Southeast Asia would likely lead to confrontation with the United States;Schom, p. 43 thus the U.S. became Japan's primary potential enemy. The U.S. possessed significantly greater industrial power than Japan, with 32.2% of worldwide industrial production compared to Japan's 3.5%.Willmott, p. 22 Furthermore, several leading members of the United States Congress had pledged "to outbuild Japan three to one in a naval race". Consequently, as Japanese industrial output could not compete with American industrial power, Japanese ship designers developed plans for new battleships individually superior to their counterparts in the United States Navy.Garzke and Dulin, p. 45 Each of these battleships would be capable of engaging multiple enemy capital ships simultaneously, eliminating the need to expend as much industrial effort as the U.S. on battleship construction.
Design
Preliminary studies for a new class of battleships began after Japan's departure from the League of Nations and its renunciation of the Washington and London naval treaties; from 1934 to 1936, 24 initial designs were put forth. These early plans varied greatly in armament, propulsion, endurance, and armor. Main batteries fluctuated between guns, while the secondary armaments were composed of differing numbers of , , and guns. Propulsion in most of the designs was a hybrid diesel-turbine combination, though one relied solely on diesel and another planned for only turbines. The maximum range of the various designs was between in design A-140-J2 and a high of in designs A-140A and A-140-B2, at a speed of . Armor varied between providing protection from the fire of 406 mm guns to enough protection against 460 mm guns.Garzke and Dulin, pp. 45–51
After these had been reviewed, two of the original 24 were finalized as possibilities, A-140-F3 and A-140-F4. Differing primarily in their range ( versus at ), they were used in the formation of the final preliminary study, which was finished on 20 July 1936. Tweaks to that design resulted in the definitive design of March 1937,Garzke and Dulin, pp. 49–50 which was put forth by Rear Admiral Keiji Fukuda; a range of 7,200 nmi was finally decided upon, and the hybrid diesel-turbine propulsion was abandoned in favor of turbines. The diesel engines were removed from the design because of problems with the engines aboard the submarine tender Taigei. Their engines, which were similar to the ones that were going to be mounted in the new battleships, required a "major repair and maintenance effort"Garzke and Dulin, p. 49 to keep them running due to a "fundamental design defect". In addition, if the engines failed entirely, the armored citadel deck roof that protected the proposed diesel engine rooms and attendant machinery spaces would severely hamper any attempt to remove and replace them.Garzke and Dulin, p. 50
The final design called for a standard displacement of and a full-load displacement of ,Garzke and Dulin, p. 53 making the ships of the class the largest battleships yet designed, and the largest battleships ever constructed. The design called for a main armament of nine 460 mm naval guns, mounted in three triple-gun turrets—each of which weighed more than a 1930s-era destroyer. The designs were quickly approved by the IJN high command,Johnston and McAuley, p. 122 over the objections of naval aviators, who argued for the construction of aircraft carriers rather than battleships.Reynolds, pp. 5–6Even as far back as 1933, IJN aviators, including Admiral Isoroku Yamamoto, argued that the best defense against U.S. carrier attacks would be a carrier fleet of their own, not a battleship fleet. However, "when controversy broke into the open, the older, conservative admirals held firm to their traditional faith in the battleship as the capital ship of the fleet by supporting the construction of the ...Yamato-class superbattleships." See: Reynolds, pp. 5–6 In all, five Yamato-class battleships were planned.
Ships
Although five Yamato-class vessels had been planned in 1937, only three—two battleships and a converted aircraft carrier—were completed. All three vessels were built in extreme secrecy, to prevent American intelligence officials from learning of their existence and specifications; indeed, the United States' Office of Naval Intelligence only became aware of Yamato and Musashi by name in late 1942. At this early time, their assumptions on the class's specifications were quite far off; while they were correct on their length, the class was given as having a beam of —in actuality, it was about and a displacement of 40,000–57,000 tons (actually, 69,000 tons). In addition, the main armament of Yamato class was given as nine guns as late as July 1945, four months after Yamato was sunk.Friedman, p. 308Johnston and McAuley, p. 128
Both Jane's Fighting Ships and the Western media also misreported the specifications of the ships. In September 1944, Jane's Fighting Ships listed the displacement of both Yamato and Musashi as 45,000 tons. Similarly, both The New York Times and the Associated Press reported that the two ships displaced 45,000 tons with a speed of 30 knots, and even after the sinking of Yamato in April 1945, The Times of London continued to give 45,000 tons as the ship's displacement. Nevertheless, the existence of the ships—and their supposed violation of naval treaties—heavily influenced American naval engineers in the design of the 60,500-ton s, though they were not designed specifically to counter the Yamato class.W. D. Puleston, The Armed Forces of the Pacific: A Comparison of the Military and Naval Power of the United States and Japan (New Haven: Yale University Press, 1941), pp. 208–211.
+ Construction dataNameNamesakeBuilderLaid downLaunchedCommissionedFateYamato Province (Great Harmony)Kure Naval Arsenal4 November 19378 August 194016 December 1941Sunk by aircraft during Operation Ten-Go, 7 April 1945Musashi ProvinceMitsubishi Heavy Industries, Nagasaki29 March 19381 November 19405 August 1942Sunk by aircraft during the Battle of the Sibuyan Sea, 24 October 1944Shinano ProvinceYokosuka Naval Arsenal4 May 19408 October 194419 November 1944Converted into aircraft carrier, July 1942; Torpedoed and sunk by USS Archerfish, 28 November 1944Warship Number 111 rowspan=2 Kure Naval Arsenal7 November 1940 rowspan=2 rowspan=2 Cancelled March 1942 when 30% complete; Scrapped in placeWarship Number 797 Cancelled during planning
Yamato
was ordered in March 1937, laid down 4 November 1937, launched 8 August 1940, and commissioned 16 December 1941. She underwent training exercises until 27 May 1942, when the vessel was deemed "operable" by Admiral Isoroku Yamamoto. Joining the 1st Battleship Division, Yamato served as the flagship of the Japanese Combined Fleet during the Battle of Midway in June 1942, yet did not engage enemy forces during the battle.Willmott, p. 93 The next two years were spent intermittently between Truk and Kure naval bases, with her sister ship Musashi replacing Yamato as the flagship of the Combined Fleet. During this time, Yamato, as part of the 1st Battleship Division, deployed on multiple occasions to counteract American carrier raids on Japanese island bases. On 25 December 1943, she suffered major torpedo damage at the hands of and was forced to return to Kure for repairs and structural upgrades.