IJN Yamato

By the late 1930s Japan faced a strategic dilemma. It could never hope to match the industrial might of the United States in sheer numbers of warships, so its naval planners reached for a different answer: quality over quantity. If each Japanese battleship were individually so powerful that it could defeat two or three American ships at once, the numerical gap might be overcome. From this thinking sprang the most colossal warships ever conceived.

Designed in the deepest secrecy and built behind elaborate concealment at the Kure Naval Arsenal, Yamato was the lead ship of a class intended to be the ultimate expression of the battleship. Named for the ancient province at the heart of the Japanese nation, she was commissioned in December 1941 — just days after the attack on Pearl Harbor that her own navy had launched, and which, ironically, had already begun to render her kind obsolete.

Yamato was a ship of staggering dimensions and power. She displaced over 70,000 tons at full load — far larger than any other battleship ever built — and carried the most powerful naval guns ever mounted afloat: nine 460mm (18.1-inch) guns, each capable of hurling a 1.5-ton shell over 40 kilometres. A single one of her three triple turrets weighed more than an entire destroyer.

She was armoured to match. Her belt and turret faces were of immense thickness, designed to withstand the fire of her own gigantic guns, making her arguably the most heavily protected warship in history. To Japanese strategists she embodied the long-cherished dream of the “decisive battle” — a single climactic fleet engagement in which her overwhelming firepower would annihilate the American battle line.

But that battle would never come. Even as Yamato was being completed, the carrier strikes at Pearl Harbor and Taranto, and the sinking of Force Z off Malaya, proved that the aircraft, not the big gun, now ruled the sea. Yamato was commissioned on 16 December 1941, nine days after the attack on Pearl Harbor had shown what carrier aircraft could do to a line of battleships at anchor.

The protection matched the guns and then exceeded them. The main belt was 410 mm set at an inclination of 20 degrees; the armoured deck ran 200 mm thick, and 230 mm over a quarter of its area; the underwater protection was 5.1 m deep and specified to absorb a 400 kg charge. The turret faces were 650 mm — thicker than the belt, thicker than anything ever fitted to a warship before or since, and thick enough in principle to keep out her own 1,460 kg shells at battle range. Those figures are the whole basis of the ship's reputation for invulnerability, and until 1946 nobody outside Japan had ever fired at one.

Then somebody did. A 26-inch (660 mm) turret face plate, manufactured for the third hull Shinano and never fitted because she was completed as a carrier, was taken to the US Naval Proving Ground at Dahlgren and shot at with the 2,700 lb 16-inch Mark 8 armour-piercing projectile. At a striking velocity of 1,992 fps the shell went completely through. At 1,707 fps the nose buried itself 21 inches into the plate without coming out the far side. Analysing the results, the plate was rated at 0.839 of the quality of American Class A armour — the standard of the best British armour of the First World War.

The metallurgy explains the number. Japanese Vickers Hardened plate was face-hardened by a pre-1914 British process that had never been intended for plates thicker than about 17 inches; on a 26-inch slab the cooling was too slow, leaving too much upper bainite in the structure and an interior that was brittle enough to crack and laminate around a hit. One plate fired at twice is not proof of what every plate on Yamato would have done, and the plate tested was one her sister never carried — but it is the only physical evidence anyone has, and it points the same way as the belt's other known defect: the jointing between the upper and lower belt armour was poor enough to leave a rupture-prone seam just below the waterline.

Yamato had one completed sister, Musashi, equally vast and equally powerful. A third hull, Shinano, was converted during construction into a giant aircraft carrier — a tacit admission of where naval power now lay — only to be sunk by an American submarine days after commissioning.

For much of the war the two giant battleships lay at the great anchorage of Truk and in home waters, hoarded for the decisive battle that never materialised. Their crews and the fuel they consumed earned them a sardonic nickname in the rest of the fleet: the “Hotel Yamato” and “Hotel Musashi,” floating palaces that seemed to contribute little while smaller ships did the dying.

Yamato's combat career was strikingly brief for so mighty a ship. She served as flagship of the Combined Fleet, present but largely inactive at Midway in 1942. Her one major surface action came at Leyte Gulf in October 1944, where she finally fired her 460mm guns at enemy ships, engaging American escort carriers and destroyers off Samar before the Japanese force inexplicably turned away on the brink of a breakthrough.

Her sister Musashi had already shown the family's fate: at Leyte she was overwhelmed and sunk by relentless American carrier air attack, absorbing an extraordinary number of bombs and torpedoes before going down. The lesson — that no amount of armour could save a battleship from massed aircraft — would soon be visited upon Yamato herself.

In April 1945, with the Americans landing on Okinawa, Yamato was sent on a final, deliberately sacrificial mission: Operation Ten-Go. With only enough fuel for a one-way voyage, she was to fight her way to Okinawa and beach herself as an unsinkable gun battery to support the island's defenders — a suicide sortie in the spirit of the kamikaze.

She never arrived. On 7 April 1945, American carriers launched hundreds of aircraft against her. For two hours Yamato endured a hurricane of bombs and torpedoes, her great guns unable to fend off the swarming attackers. Listing ever further as compartment after compartment flooded, she finally capsized and her magazines exploded in a blast so enormous it was seen and heard for miles, sending up a mushroom cloud thousands of metres high. Of her crew of nearly 3,000, only a few hundred survived.

With Yamato died the last great battleship sortie of the war, and with it the battleship era itself.

IJN Yamato was the largest, heaviest and most powerfully armed battleship ever built — the ultimate refinement of a type of warship that the very war she was built for had already made obsolete. She fired her colossal guns at the enemy only once, and was destroyed not by another battleship but by aircraft, in a one-way suicide mission that achieved nothing militarily.

In Japan she became a symbol of national pride and sacrifice, and she remains a fixture of postwar popular culture there. She fired her main battery at an enemy surface force once, off Samar on 25 October 1944, and was sunk by carrier aircraft on 7 April 1945.

• Janusz Skulski, The Battleship Yamato (Anatomy of the Ship, Conway) — the definitive structural study.
• Russell Spurr, A Glorious Way to Die: The Kamikaze Mission of the Battleship Yamato (1981).
• William H. Garzke & Robert O. Dulin, Battleships: Axis and Neutral Battleships in World War II (Naval Institute Press).
• Jonathan Parshall & Anthony Tully, Shattered Sword (Potomac, 2005) — for the Japanese fleet in context.
• U.S. Naval Proving Ground, Dahlgren — ballistic test of the IJN Shinano turret face plate (1946–47), analysed by Nathan Okun.