In 1944, the super-carrier Shinano was torpedoed and sunk without ever having launched a single airplane.
"Hidden History" is a diary series that explores forgotten and little-known areas of history.
IJN Shinano, photographed during her sea trials photo from WikiCommons
In the years before the Second World War, the Japanese Imperial Navy, despite having the largest aircraft carrier force in the world, still clung to the belief that the battleship was the supreme weapon at sea. After the 1922 Washington Treaty (which limited the size of battleships) expired, Japan began construction of a new class of super-battleship. The Yamato entered service in December 1941, and the Musashi in August 1942. With their massive 18-inch guns, the super-battleships were intended to win supremacy in the Pacific for the Imperial Navy.
The pre-war US Navy also believed that its fleet of battleships was the most powerful sea force in the world, and could defeat any potential threat. But when the American battleships were destroyed by air attack at Pearl Harbor, the United States had to develop a brand new strategy, utilizing the only forces that it had remaining after the strike—the carriers and the submarines.
As it turned out, this was exactly what was needed anyway: carrier air power was the key to pushing Japan out of its island fortresses, and the American submarine fleet systematically destroyed Japan’s merchant shipping, removing its ability to transport supplies and materials and preventing the Japanese from replacing their losses of ships and planes.
In the last two years of the war, American submarines sunk 4.9 million tons of Japanese shipping, including 1,178 merchant cargo ships and 214 Japanese Navy combat ships, including 8 aircraft carriers, 1 battleship, and 11 heavy cruisers—about 60% of all Japanese ships lost during the war. By 1944, Japan's shipping losses were twice that of her construction. Japan started the war with 6 million tons of cargo shipping, and ended it with less than 3 million. Japanese imports of iron, aluminum ore, cotton, rubber, and lumber all fell by over 90% during the war. The loss of gas and oil tankers was so severe that the Imperial Navy was confined to port for lack of fuel, and was making desperate plans to build huge oil-tanker submarines and aircraft that could deliver supplies to Japan without exposing themselves to submarine attack.
One of the most significant targets to fall victim to the American subs was the Shinano.
Originally, the Japanese had planned to build five of the Yamato-class super-battleships. In the end, economic limits and the onset of the war meant that only two were completed. But the Imperial Navy had also begun construction of a third battleship, to be named Shinano, in May 1940, and a fourth, to be christened Kii, in November. When the war began, however, they fell to low priority. By the time of the Battle of Midway in June 1942, Shinano was still just an empty hulk about half-finished, and Kii had barely been started.
With the loss of most of their carriers at Midway, the Imperial Navy became desperate. It needed carriers in a hurry, and the fastest way to get them was to convert already-existing hulls by adding a flight deck. Kii had already been canceled in March 1942 and her steel plates recycled into other priorities. But now the Japanese halted work on Shinano’s hull and drew up plans to convert her into a 72,000-ton super-carrier, twice as big as previous fleet carriers like Akagi.
It was all done in strict secrecy. The Yokosuka shipyard in Tokyo Bay was surrounded by a high wall, and cameras were forbidden in the area. Kempeitai military police patrolled the area.
Shinano was intended to be the most powerful aircraft carrier in the world. Her flight deck would be 870 feet long and armored against the largest of air-dropped armor-piercing bombs, while a belt of armor at the waterline and a network of internal watertight doors would protect against torpedoes. Her immense hangar would have room for almost 150 combat aircraft. She even had enough room to carry and launch two-engined medium bombers. With 16 5-inch anti-aircraft guns and almost 150 25mm cannon, she bristled with AA. Shinano would also have the best electronic radar technology that Japan could provide, and, utilizing the same engines found in Yamato and Musashi, her speed of 27 knots and range of 10,000 nautical miles meant that she could reach any American base in the Pacific. She would, it was hoped, turn the Imperial Navy into an effective fighting force again.
By the autumn of 1944, Shinano was nearing completion. But the war situation for Japan had become desperate. Nearly all of the Navy’s outer defensive circle had been lost, American B-29s based in the Marianas had already begun nightly incendiary raids on Japanese cities, most of the Imperial Fleet had already been destroyed, and the remains of Japanese air forces were reduced to making futile suicide attacks on American carriers. The primary task for the Japanese military was now to hold the inner circle of defenses that still protected the home islands.
So Shinano’s intended mission was altered. She would no longer be equipped as an attack carrier (there were not enough trained and experienced pilots left for that anyway). Instead, the super-carrier would function as a floating airbase which could be used for repairing, transferring and maintaining the massive fleet of Kamikaze aircraft that would be gathered in the home islands and launched in last-ditch suicide attacks against invading American forces.
In November 1944, the decision was made to move Shinano from Tokyo Harbor, where she was vulnerable to B-29 raids, to the naval base at Kure, further away. This was resisted by her Captain, Toshio Abe. Although Shinano’s outer hull and flight deck were finished, most of the internal structure was still missing. Only half of the engines were in working order. In particular, there were no watertight doors, pumps, or fire-suppression systems installed yet. This, Abe pointed out, made his ship enormously vulnerable—a single hit from an American bomb or torpedo could flood the entire interior. But the Imperial Navy Admirals were adamant: the ship was, they replied, Japan’s only remaining hope, and it had to be protected.
Abe was ordered to take Shinano out into Japan’s Inland Sea, under cloak of darkness—with no planes of her own and no land-based air cover, and accompanied only by three destroyers—and sail to Kure, where the carrier would finish her fitting-out before being loaded with 100 Ohka piloted rocket-powered bombs, to be brought back to Tokyo for deployment as suicide weapons against invasion. With few trained Navy sailors available, Shinano’s crew consisted of green recruits and a contingent of civilian dockyard workers who had been shanghai’d into service.
On the night of November 29, 1944, the American submarine Archerfish had been sent to the Inland Sea on “lifeguard” duty—standing by on the surface in case she was needed to pick up aircrew from any damaged B-29s that had to ditch in the water. Now, their monotony was broken when a blip appeared on their sonar, about 12 miles away. Lookouts soon spotted a ship on the horizon, and when Commander Joseph Enright looked through his binoculars, he was met by the sight of the biggest aircraft carrier he had ever seen. When he looked through his “recognition handbook” of Japanese ships, nothing matched the behemoth he was looking at—the US had no idea that the Shinano even existed.
On the Shinano, Captain Abe’s crew heard the sonar ping and knew there was a submarine nearby, and Abe, fearing that this was a decoy to lure him into a “wolfpack” of subs, began to zigzag.
Archerfish then submerged and moved into attack position. Shinano’s course was taking it away from the sub at a speed the Americans couldn’t match. But Archerfish nevertheless trailed the carrier for several hours, and at around 3am Shinano turned back to her original course. It took her directly towards the American submarine.
Captain Enright fired four torpedoes at the huge carrier, which tore open the side of the ship. As water began to pour in, there were no countermeasures available to stop it. By 9am Shinano had lost all power, and after one of the destroyers tried unsuccessfully to tow the huge carrier, Captain Abe ordered his crew to abandon ship. Shinano disappeared at 1pm. With her went Japan’s last hope.
NOTE: As some of you already know, all of my diaries here are draft chapters for a number of books I am working on. So I welcome any corrections you may have, whether it's typos or places that are unclear or factual errors. I think of y'all as my pre-publication editors and proofreaders. ;)
