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 USS Archerfish 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.

[11] 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.

[13] When Japan withdrew from the League of Nations in 1934 over the Mukden Incident, it also renounced all treaty obligations,[14] freeing it to build warships larger than those of the other major maritime powers.

[6] 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.

[21] 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"[23] to keep them running due to a "fundamental design defect".

[34] 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.

[22] During this time period, 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 USS Skate and was forced to return to Kure for repairs and structural upgrades.

[22] In 1944—following extensive anti-aircraft and secondary battery upgrades—Yamato joined the Second Fleet in the Battle of the Philippine Sea, serving as an escort to a Japanese Carrier Division.

[22] Yamato was deliberately expended in a suicide mission as part of Operation Ten-Go, sent to use her big guns to provide relief to Japanese forces engaged in the Battle of Okinawa.

The savings in weight this entailed meant that improvements could be made in other areas, including added protection for fire-control and lookout positions.

Although smaller, this gun was superior to the 127 mm, possessing a significantly greater muzzle velocity, maximum range, anti-aircraft ceiling, and rate of fire.

[47][48] Warship Number 111, never named, was planned as the fourth member of the Yamato class and the second ship to incorporate the improvements of Shinano.

Even though they comprised 40% of the total main ammunition load by 1944,[52] 3 Shiki tsûjôdan were rarely used in combat against enemy aircraft due to the severe damage the firing of these shells inflicted on the barrels of the main guns;[55] indeed, one of the shells may have exploded early and disabled one of Musashi's guns during the Battle of the Sibuyan Sea.

Initially, heavy anti-aircraft defence was provided by a dozen 40-caliber 127-mm Type 89 dual-purpose guns in six double turrets, three on each side of the superstructure.

In 1944, the two amidship 15.5 cm turrets were removed to make room for three additional 127-mm mounts on each side of Yamato, bringing the total number of these guns to twenty-four .

[53] In 1944, both Yamato and Musashi underwent significant anti-aircraft upgrades in preparation for operations in Leyte Gulf[60] using the space freed up by the removal of both midships 15.5 cm (6.1 in) secondary battery turrets,[61] and ended up with a complement of twenty-four 12.7 cm (5.0 in) guns,[61] and one hundred and sixty-two 25 mm (0.98 in) antiaircraft guns,[61] The 25 mm anti-aircraft guns could tilt at 90-degree angles to aim at planes directly overhead, but their mountings' lack of protection made their gunnery crews extremely vulnerable to direct enemy fire.

[63] This was the standard Japanese light AA gun during World War II; it suffered from severe design shortcomings that rendered it a largely ineffective weapon.

[67] Designed to engage multiple enemy battleships simultaneously,[4] the Yamatos were fitted with heavy armor plating described by naval historian Mark Stille as providing "an unparalleled degree of protection in surface combat".

[69] Furthermore, the top hull shape was very advanced, the peculiar sideways curving effectively maximizing armor protection and structural rigidity while optimizing weight.

This may have been the result of overestimating the effectiveness of the lower belt armor against torpedoes, an effort to decrease draft, and provision of additional counter-flooding spaces.

However, despite the immense armor thickness, the protection scheme of the Yamato class still suffered from several major design flaws and shortcomings.

[75] Structural weakness existed near the bow of the vessels, where the armor plating was generally thinner, as demonstrated by Musashi's damage from a torpedo hit in 1943.

[55] The hull of the Shinano was subject to even greater structural weakness, being hastily constructed near the end of the war and having been equipped with incomplete armor and unsealed watertight compartments at the time of her sinking.

Joint failures have been attributed to the considerable damage inflicted upon Yamato from a single torpedo impact in 1943, and to the sinking of Shinano from four hits in 1944.

The Japanese loss in the Battle of Midway, where four carriers were sunk (out of ten, at that time, in the entire navy), made it certain that work on the ships would never begin.

The destruction of these documents was so efficient that until 1948 the only known images of Yamato and Musashi were those taken by United States Navy aircraft involved in the attacks on the two battleships.

[80] However, in October 1942, based upon a special request from Adolf Hitler, German Admiral Paul Wenneker, attached to the German Naval Attache in Japan, was allowed to inspect a Yamato-class battleship while it was undergoing maintenance in a dockyard, at which time Admiral Wenneker cabled a detailed description of the warship to Berlin.

On 22 August 1943, Erich Groner, a German naval historian, and author of the book Die Deutschen Kriegschiffe, 1815–1945, was shown the report while at the "Führer Headquarters", and was directed to make an "interpretation" and then prepare a "design sketch drawing" of the Japanese battleship.

[83] The appearances in popular culture usually portray the ship's last mission as a brave, selfless, but futile, symbolic effort by the participating Japanese sailors to defend their homeland.