IJN Musashi was sister to the famous IJN Yamato and the second of the powerful warships built to the class standard - she was sunk in October of 1944.
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The Japanese expansion over the Pacific required a considerable naval force and this was to be directed by the powerful Imperial Japanese Navy arm prior to, and during all of, World War 2 (1939-1945). Knowing that the service would not be able to compete numerically with the American Navy - the prime threat to its expansionist dreams in the region - the IJN adopted a policy of quality over quantity. This led to design and development of a new class of surface combatant, one that would eventually lead the IJN to possess the most powerful battleship class in the entire world, the Yamato-class.
Two ships were built to the standard under a high level of secrecy for there were still standing naval treaties that the Empire of Japan had signed onto with after World War 1 (1914-1918). These treaties mainly limited participants to ships of restricted tonnage so as to help thwart another naval arms race like the one that preceded the fighting of The Great War. Work on the Yamato-class was begun as soon as 1934 and engineers were given the challenge of generating a warship with no equal during the period - armed with powerful main guns, well protected through skillful use of armor plating, and offer performance unmatched for its size. In this fashion, the mighty warships - a total of five originally planned - could move throughout the Pacific realm with impunity and outgun and outlast any opponent that dared to stand in their way.
Beyond the engineering challenges of developing these steel beasts were the political ones. The treaties were meant to hamper such thinking but if the participants care little for repercussions of breaking them, then there stood little point in the agreements to begin with. Beyond this, however, was in building such grand warships without drawing the attention (and subsequent ire) of both the Americans and the British who both held high levels of interest in their respective Pacific region holdings. There were plans to reject or delay the ratification of the upcoming naval treaties of 1936 so as to give the IJN enough time to construct their massive ships available for when the tonnage restrictions were set to expire in 1940. The IJN also felt that for the Americans to attempt to match such warships and construct similar types through their storied East Coast shipyards, they would have to commit to widening and deepening the Panama Canal for passage into Pacific waters - and this seemed very unlikely.
Of the five Yamato ships planned, just three ultimately received names - lead ship Yamato herself and sisters Musashi and Shinano. The final two were cancelled, the first in 1942 as it lay about 30% complete and, the second, as it was still in the planning stages. Of note is that Shinano was converted to an aircraft carrier to shore up losses for the IJN carrier fleet. None of the active-serving Yamato-based warships survived the war (Yamato lost in Operation Ten-Go, 1945, Musashi was sunk during the Battle of the Sibuyan Sea, 1944, and the carrier Shinano was sunk by U.S. submarine in 1944).
In 1937, the Empire of Japan enacted the 3rd Reinforcement Program meant to strengthen the fleet as it headed to inevitable war with the United States. Yamato was laid down by Kure Naval Arsenal in November of 1937 and launched in August of 1940. She was commissioned in December of 1941. Her sister, IJN Musashi - the subject of this article - was laid down by Mitsubishi Heavy Industries of Nagasaki on March 29th, 1938 and launched on November 1st, 1940. She was formally commissioned for service on August 5th, 1942.
As built, IJN Musashi displaced 65,000 tons under standard loads and up to 72,810 tons under full loads. She held an overall length of 800.5 feet with a beam measuring 121 feet and a draught down to 35.7 feet. Power came from 12 x Kanpon water-tube boilers feeding 4 x Steam turbines developing 150,000 horsepower to 4 x Shafts under stern. This gave the vessel a top speed of 27.5 knots with a range out to 7,200 nautical miles. Aboard was a crew of 2,500 personnel. Two catapults served the six or seven Nakajima-brand floatplanes which were recoverable by onboard crane. Type 21 air-search radar was carried as was a Type 0 hydrophone system.
Armament and Armor
Armament became 9 x 460mm (18") Type 94 main guns set as three triple-gunned turrets. This was backed by 12 x 155mm (6") 3rd Year Type Dual-Purpose (DP) secondary guns held in four triple-gunned turrets. 12 x 127mm (5") Type 89 guns in six twin-gunned turrets offered a heavy punch against attacking enemy aircraft and 36 x 25mm (1") Type 96 guns in twelve triple-gunned emplacements were carried for similar reasons. Rounding out the armament fit were two or more 13.2mm Type 93 heavy machine guns for extreme close-in defense against aerial targets.
Armor protection included 15.7" at the waterline, up to 9.1" at the deck, 25.6" being reached at the gun turrets, 22" found along the barbettes, 19.7" seen at the conning tower, and up to 13.4" in thickness found at the bulkheads.
Fast, well-armored and powerfully-armed, IJN Musashi and her sister were exactly what IJN authorities had envisioned. After commissioning in August of 1942, the warship joined Yamato, Nagato, and Mutsu as part of the 1st Battleship Division.
Musashi's part in World War 2 came to an abrupt end during the Battle of Leyte Gulf. The battle involved forces of the IJN pitted against the Australian and American navies for control of Leyte Gulf and the Philippines. Outnumbered, the IJN forces fell badly in this decisive Allied victory of the war. Musashi, Yamato, and Nagato were part of Vice-Admiral Kurita's Force A contingent during the melee. During the subsequent retreat action of the Japanese, Musashi was one of the warships to fall to attacking American naval aircraft - sunk by direct hits from some nineteen torpedoes and a further seventeen aerial bombs (all estimated totals). Taking on water, listing, and sinking at the bow, the warship was sent to Davy Jones's Locker with her crew abandoning ship after the battle. The vessel went down in over 4,400 feet of water with 1,376 of her 2,399 crew saved. Her wreckage was not discovered and identified until March of 2015 by American researchers.