In October 1934, the Japanese Naval General Staff made a request that would set the size of the largest battleships ever completed. They asked the Bureau of Naval Construction to study a new battleship armed with 18-inch guns. Captain Kitaro Matsumoto, a naval architect present from the first drawing, later explained the reasoning. Japan could not match American shipyards hull for hull, so each Japanese ship had to be so powerful that the United States could not answer it for years.
The second requirement involved the Panama Canal. The planners wanted a ship so large that whatever Washington built to fight her could not pass from one ocean to the other. They judged it unlikely that even the United States would pay for two full battle fleets, one on each coast. The bureau worked the problem from the other direction.
By its reckoning, the largest battleship the canal locks could pass would displace 63,000 tons, make 23 knots or less, and carry ten 16-inch guns. Every figure that followed was set to beat that ship. The guns went to 18 inches because a ship held to the locks would be held to 16. The belt went to 16 inches of steel, enough to stop an 18-inch shell fired from beyond 20 kilometers.
The hull went wide enough to carry that armor over twelve boilers set out in four lines of three side by side, an arrangement only a ship of that breadth could hold. The design office worked the problem with tolerance. Its first drawing in March 1935 came out 294 meters long and 41. 2 meters wide, good for 31 knots.
The staff itself found that too big and gave up speed, settling for about 27 knots in a navy that had always prized it. By the following summer, the dimensions were nearly final, with steam turbines paired with big diesel engines for range. Two months later, a basic fault turned up in the same class of diesel already running in three submarine tenders. The new ship’s engine rooms would sit under eight inches of armor, and nothing installed beneath that deck was ever coming out again.
The designers dropped the diesels, fitted turbines of 150,000 shaft horsepower, and finished the final drawing the next March. Before the shape was fixed, the Navy towed fifty hull models down its test tank in Tokyo, the largest in the country. One result was a bulb on the stem so large that it cut resistance by 8. 2 percent at 27 knots.
On her full power trial, she made 27. 5. Then the Navy rebuilt the yards to fit the drawing. At Kure, it deepened the building dock by about a meter so the finished hull could float and raised the gantry crane above it to 100 tons to swing armor plate.
It roofed over the far quarter of the dock because a hill near the yard looked straight down into it. The keel of battleship number one went down there on November 4, 1937. The armor needed its own plant as well. About ten million dollars went into new mills, and a single side plate came off them nearly twenty feet long, sixteen inches thick, and 68.
5 tons in weight. At the Mitsubishi yard in Nagasaki, the second ship would go down a slipway with a launching weight of more than 35,000 tons. Mitsubishi strengthened the ways, added almost sixty acres of workshops, and built floating cranes rated at 350 and 150 tons to lift armor and gun fittings. Yokosuka got a new dry dock for a third ship, and Kure got another.
The guns set a problem no yard could solve alone. Every one of them was made at Kure. One turret with its three guns weighed 2,774 tons, as much as a large destroyer, and the parts could reach Nagasaki or Yokosuka only in a ship built for the purpose. So the Navy built one.
She was the Kashino, laid down at Nagasaki in July 1939 and rated on paper as an auxiliary turret conveyance warship. In October 1941, she brought the first of the second ship’s big guns and a turret up from Kure, and the yard’s big floating crane swung them aboard. The yard covered them in canvas as soon as they touched the deck. Secrecy ran as a department of the same machine.
In every paper, the gun was called the special type 40 centimeter, a name that made it sound like a 16-inch weapon. The bore was 46 centimeters. At Nagasaki, the slipway hung behind a curtain of fiber rope so large that fishermen in Kyushu ran short of it. The afternoon before the second ship went into the water, the yard shut its gates without warning and cut communications with the outside.
Workers heard the launching hour that day and worked through the night. She slid in at 8:55 on the morning of November 1, 1940, in front of a few dozen senior officers while police, military police, and sailors, about 1,800 men in all, kept the town away from the water. As soon as she was afloat, tugs brought a new passenger liner, the Kasugamaru, alongside her to break up her outline. She was named Musashi that morning.
Most official papers went on calling her warship number two until she joined the fleet. The deception worked on the people it was built to deceive. In January 1938, the American naval attaché in Tokyo, Captain Harold Bemis, reported two 16-inch battleships under construction, considerably heavier than the old treaty limit. The British, German, and French attachés put them at 45,000 tons.
The Soviet attaché decided Japan could not turn guns that big at all without buying the machinery abroad. In October 1942, the Office of Naval Intelligence had the ships at 35,000 tons with nine 16-inch guns. A year later, an intercepted message mentioned special type 40-centimeter ammunition, and that held the 16-inch figure in place. In February 1944, two American reconnaissance aircraft photographed the fleet anchorage at Truk.
A float plane from the Musashi climbed after them and could not catch up. One frame caught one of the big ships in a corner. At Pearl Harbor, the photo interpreters called her guns 18 inches, and the ship design experts brought in to check agreed she had to displace at least 60,000 tons. Then the same experts argued against their own figures and called such a ship impractical on grounds of stowage, propulsion, docking, and navigation.
The ship was sitting in their photograph at the time. The historian John Prados, in his account of American codebreaking against the Japanese Navy, describes what finally moved the number. In June, a prisoner taken on Saipan, Mitsuharu, once a yeoman to Admiral Yamamoto, repeated the jokes Japanese sailors told about their special type 16-inch guns. Edwin Layton, the Pacific Fleet Intelligence Officer, and until then a firm believer in 16-inch guns, gave the figure up.
The intelligence weekly in Washington was still printing 40,000 tons at the end of August. The rule the Japanese had built against was real. Since the canal opened, American battleships had been drawn to its locks, 110 feet wide with a thousand feet of usable length. The North Carolina and the South Dakota classes came out about two feet narrower than the chambers.
The Iowas, faster still, kept that beam and found their speed in a longer hull instead. But the rule could move. On August 11, 1939, Congress authorized a third set of locks thirty feet wider than the old ones at a cost put at 277 million dollars. Dredges started on the Pacific approach on July 1 the following year.
Eighteen days later, the Two-Ocean Navy Act authorized five battleships of the Montana class, each 121 feet in the beam, too wide for the old locks on the understanding that wider ones were coming. The assumption in Tokyo had been poured into armor that could never be altered, and the country it described was still free to change its mind. Neither the ships nor the locks were finished. The Navy suspended the Montana class in May 1942 before laying a single keel when carriers, antisubmarine ships, and landing craft took the steel.
On the 23rd of that month, the Secretary of War stopped the digging with almost thirteen million cubic yards already out of the ground, and the Montana class itself was cancelled in July of the next year. The Japanese Navy had spent 400 tons of fiber keeping this story out of sight. The machine’s products went to war on their own schedules. On December 1, 1941, the Kashino’s call sign was changed.
The Navy decided the next June to finish the third ship as an aircraft carrier. After that, there were no more turrets to carry. Her holds were covered over, and she hauled ammunition and stores. On September 4, 1942, seventy nautical miles northeast of Kaohsiung on Formosa, the submarine Growler under Lieutenant Commander Howard Gilmore put two torpedoes into her.
She settled by the head with her screws out of the water and stayed afloat. Gilmore opened fire with his deck gun, missed with one more torpedo, hit with the next, and she went down. The big ships carried the design’s other costs. The blast of one triple turret was about twice that of a pair of 16-inch guns, strong enough by Japanese calculation to strip the clothing off a man on the open deck and knock him out.
So the boats were stowed in hangars, and the first antiaircraft guns sat behind shields. During the Musashi’s calibration firing in July 1942, guinea pigs were put aboard to study what the blast did. The Yamato was the first Japanese warship with air conditioning, and sailors called her the most comfortable ship in the Navy. In the Sibuyan Sea on October 24, 1944, American carrier aircraft went after the Musashi in wave after wave from the middle of the morning.
Her armored center held for hours while the unarmored forward end flooded compartment after compartment. By late afternoon, she was down more than twenty-six feet by the head with her forecastle awash. At 7:36 that evening, she rolled over to port and sank. Of 2,399 men in her crew, 1,023 were lost.
How many hits it took is not settled. Matsumoto’s 1953 account, drawn from her battle report, counts seven bombs and nine torpedoes by the end of the second attack, then ten more bombs and eleven more torpedo hits in the third. Bob Hackett and Sander Kingsepp, working from her detailed action report, give nineteen torpedo hits and seventeen bombs for the day and state that the count for the last attack is still disputed. The curtain at Nagasaki has the same problem.
Matsumoto called it shirushi, more than 400 tons of rope. The same two researchers say the contemporary files named palm fiber bought in about the same weight by the Sasebo Naval District. The Yamato went out on April 6, 1945, with a light cruiser and eight destroyers, bound for the American fleet off Okinawa. The next day in the East China Sea, southwest of Kyushu, carrier aircraft caught her.
Her executive officer later counted at least seven large bombs and twelve aerial torpedoes, most of them on the port side, and she rolled over and blew up, sending up smoke that was seen one hundred miles away. Of the 3,332 men aboard her, 3,055 were lost. The papers went next. Most of the construction data for both ships burned in the confusion after the surrender in the summer of 1945.
That is why the canal figures rest on thin ground. The 63,000 tons, the ten 16-inch guns, and the 23 knots come to us through Matsumoto, who set them down in a Japanese science magazine in 1950 while his memory was still fresh. He gives the results of the canal study, and none of its working survives. The American Naval Technical Mission shipped two 18-inch guns home from Kure for study, each seventy-five feet long and 180 tons.
On November 18, 1944, one week out of Norfolk, the new battleship Missouri entered the Panama Canal westbound. Her beam was 108 feet 2 inches. The lock chambers were 110 feet wide, which left a little under a foot of water between her hull and each wall. The electric locomotives the canal calls mules held her centered from the lock walls while the chambers filled and emptied.
She came out at the Pacific end and steamed north for San Francisco, where she was fitted out as a fleet flagship.
