Article Summary: The Shinano, originally designed as a massive Yamato-class battleship, was converted into the largest aircraft carrier of World War II after Japan’s devastating carrier losses at Midway.
Key Point #1 – Rushed into service in late 1944 with an inexperienced crew and untested watertight compartments, the carrier was spotted by the submarine USS Archerfish while en route to Kure. Commander J.F. Enright fired six torpedoes, striking Shinano’s vulnerable armor joints.
Key Point #2 – Despite initial confidence in the ship’s survivability, flooding overwhelmed the carrier, and it capsized hours later. The Archerfish had sunk the largest warship of WWII, proving the deadly effectiveness of submarine warfare.
WWII’s Largest Aircraft Carrier Doomed by a Deadly Submarine Strike
Before World War II, the Imperial Japanese Navy built the largest battleships ever: the Yamato-class. Two were built, the Yamato and the Musashi. The Shinano was to be the third, and they would be the three biggest battlewagons to ever sail the sea.
The Shinano’s keel was laid in 1940, when Japan was building the most powerful navy in the world. The battleship was the king of the sea at the time, but that was to change quickly. Adm. Isoruku Yamamoto spent time in the U.S. as a naval attache. He was convinced that Japan couldn’t compete with the U.S. as a manufacturing giant, so the Japanese would have to prioritize quality over quantity.
The Shinano was part of that effort, but she was later converted to the largest aircraft carrier the world would see until the 1960s.
Just a few days after she was commissioned, the Shinano was sunk by a U.S. submarine.
Transitions to a Aircraft Carrier
Pearl Harbor devastated the U.S. Pacific Fleet, but did not knock it out. America’s aircraft carriers were not there, and those ships would turn the tide of the war in just a few months.
The Battle of the Coral Sea ended in a draw, but the Japanese were forced to withdraw. A month later, with a large dose of luck at the Battle of Midway, the Americans caught the Japanese by surprise. Japan lost four of its largest fleet carriers in a crushing defeat.
That’s when the Japanese Navy ordered the Shinano to transition from a battleship to become the largest aircraft carrier ever built.
The Shinano Is Massive But Vulnerable
Like the other massive ships of the Yamato-class, the Shinano had a weakness. The joints between the main armored belt and the armored bulkheads below were vulnerable to leakage—this would prove fatal.
The Shinano weighed a massive 69,000 tons, more than twice the weight of the U.S. Essex-class. The main deck was covered in 7.5 inches of armor. The flight deck was covered with armor 3.5 inches thick.
She was protected by sixteen 5-inch anti-aircraft guns, 145 25mm anti-aircraft machine guns, and 12 multiple rocket launchers with 4.7-inch unguided anti-aircraft rockets. But curiously, the Shinano only carried 47 aircraft, despite its size. The Essex carriers had a complement of 80-100 aircraft.
Japan had learned its lesson from Midway, so it armored the ventilation shafts that carried explosive gases and spread fires, and removed flammable materials from inside the ship.
But by late 1944, the Japanese made a fateful error. In a rush to get her to sea, the shipyards did not inspect the Shinano’s watertight compartments. The captain believed these were functional.
The Death Of the Shinano
The Shinano was supposed to be commissioned by early 1945, but during the Battle of the Philippine Sea, Japan lost two fleet carriers and a light carrier. The Americans lost 109 aircraft, but the Japanese lost more than 600. It was a disaster for the Japanese fleet.
Construction of the Shinano was rushed through, and the ship was commissioned on Nov. 19, 1944. Captain Toshiro Abe had a green crew and no aircraft, so he sailed from Tokyo to Kure to pick up his aircraft complement. They left port at 1800 hrs on Nov. 29, escorted by the destroyers Hamakaze, Isokaze, and Yukikaze.
The submarine USS Archerfish was searching for targets in Tokyo Bay. It was on its fifth patrol and still looking for its first kill. Comm. J. F. Enright, skipper of the Archerfish, picked up Shinano on radar while running surfaced late in the evening.
The officer of the deck told the radar crewmen that they were picking up Iamba Shima, an island. The radar man responded, “Well, your island is moving at 028° and 20 knots.”
Comm. Enright tried to move at flank speed to get in position to shoot. His submarine had trouble keeping up, but the carrier and escort were zig-zagging, which allowed a slight hope of catching her.
Aircraft Carrier Shinano. Image Credit: Creative Commons.
INJ Aircraft Carrier Shinano. Image Credit: Creative Commons.
It took nearly three hours, but just as the carrier appeared to lose the Archerfish, it made a sharp change in direction and headed straight for the sub. Comm. Enright gave his overworked diesels a break, and the sub descended to periscope depth.
Enright and his crew caught another break when the carrier turned again. A destroyer passed by at only 400 yards but didn’t pick up the sub. The carrier came with 1,400 yards, giving him a full broadside view.
At 0317, a spread of six torpedoes, set to run at 10 feet, were fired at the unwary carrier. Two torpedo hits were seen, and four more were heard to strike home a minute later. As destroyers maneuvered in to contact Archerfish, the submarine evaded, diving to 400 feet, confident she had dealt a mortal blow.
The captain of the Shinano, confident that his water-tight compartments were fine, continued steaming at 18 knots. But his green damage-control crew wasn’t up to speed on emergency procedures. Water rushed in; the ship was doomed. The next morning, the great ship capsized, taking more than 1,400 officers, crew, and dockyard workers to the bottom, out of the 2,300 on board.
The Archerfish had sunk the largest aircraft carrier in WWII. The torpedoes had hit the joint in the armored belt.
About the Author: Steve Balestrieri
Steve Balestrieri is a 19FortyFive National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing for 19FortyFive, he covers the NFL for PatsFans.com and is a member of the Pro Football Writers of America (PFWA). His work was regularly featured in many military publications.
