Construction of the IJN Shinano
The Imperial Japanese Navy (IJN) began construction of the Shinano at the Yokosuka Naval Arsenal on May 4, 1940.
Source: Wikimedia
The vessel was originally supposed to be a battleship. However, two years into construction, plans were changed, and the workers were ordered to convert it into an aircraft carrier following heavy losses of similar ships to the American military.
The Armor and Armament of the Vessel
The IJN Shinano was a combination of two different vessel designs, the Yamato and Musashi. Originally, it was intended to feature armor that was up to 20mm thinner than the other designs and the best Japanese anti-aircraft weapons of the era.
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In the end, the Shinano featured a flat top consistent with aircraft carriers and an inclined flight deck. It was also stripped of most of its large guns and armor.
The True Extent of the Shinano
The Shinano was an enormous ship, measuring a staggering 872 feet in length and 199 feet in beam. Its power was sourced from 12 Kampen water boilers, which, in turn, powered the four geared steam turbines.
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At full capacity, the Shinano could carry around 47 different types of aircraft utilized by the Japanese Air Force.
Weapons Aboard the Shinano
Despite being converted from a battleship to an aircraft carrier, the Shinano still packed a punch. It was equipped with eight twin-five-inch dual-purpose guns, 25 anti-aircraft rocket guns, and 28 anti-aircraft rocket launchers.
Source: Wikimedia
As for armor, the bottom half of the ship was equipped with plating that measured anywhere from 160 to 400mm thick, whereas on the flight deck, it was around 75 mm thick.
The Battle of the Philippine Sea
The IJN Shinano wasn’t set to be commissioned until the start of 1945. However, after the Japanese Navy suffered significant losses at the Battle of the Philippine Sea, construction work was ramped up to meet an earlier deadline.
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The Shinano was officially launched on October 8, 1944, and commissioned on November 19, over a month later.
Captain Toshio Abe
Shinano was under the command of Capt. Toshio Abe. The first mission was to travel to the Kure Naval Base, where it would be drifted with armaments and pick up several aircraft.
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However, it would never make it to its destination. After sailing for some time alongside three other vessels, the Isokaze, Hamakaze, and Yukikaze, they detected the presence of a US submarine on their radar. Following this, the ships began employing evasive maneuvers.
USS Archerfish Spots the IJN Shinano
Reports suggest Cmdr. Joseph Enright, who commanded the submarine USS Archerfish, had spotted the Japanese vessels at least two hours before they noticed they were being tailed.
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The Japanese captain ordered the ships to turn away from the submarine, thinking they had encouraged an American wolfpack. While the Shinano was faster, it was forced to speed to prevent significant damage to the vessel.
Submarine Fires Torpedoes at Japanese Carrier
In the early hours of the morning on November 29, 1944, the Japanese captain decided to change direction and move towards the submarine. The Shinano ended up exposing the entire side of the vessel, which the Archerfish decided to capitalize on.
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It didn’t take long before Enright made the call to fire upon the Japanese aircraft carrier, launching six torpedoes. The American Commander received word that the first two had made contact before dropping the submarine down 400 feet to await the results of his actions.
Submarine Sinks IJN Shinano
Four of the six torpedoes made contact with the IJN Shinano, which was enough to seal the vessel’s fate. While those aboard the Japanese aircraft carrier initially thought the damage was minimal, by the time they realized the ship was going down, it was already too late.
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By the time the crew became aware of the danger, it was too late to escape. Of the 2,400 crew aboard, over 1,435, including the captain, went down with the ship.
Design Flaws in the Japanese Ships
Following the culmination of World War 2, American experts carried out in-depth analyses of numerous Japanese ships, including the remains of the Shinano.
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They discovered a major design flaw that made several joints prone to leakage. It was later theorized that Archerfish’s torpedoes managed to hit these joints, which played a significant role in the demise of the Shinano.
American Commander Awarded Navy Cross
US Naval Intelligence didn’t initially believe Enright following his claims that the Archerfish had sunk the Shinano.
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However, after the war, the decision was corrected, and the Commander was awarded the prestigious Navy Cross for his actions that led to the largest sinking of a Japanese aircraft carrier by a submarine in history.
