The Japanese supercarrier, a symbol of naval power, met an unforeseen and tragic end when it was sunk by the American submarine, USS Archerfish, resulting in the devastating loss of 1,435 of the ship’s crew.

Japan had great success with its Navy for several reasons, including its collection of battleships and cruisers, well-trained crews, and cutting-edge technology of the era. 

One vessel that would go down in history is IJN Shinano, a vessel built in secrecy, which the Japanese Navy hoped would help them in their fight to retain control of the Pacific Ocean. 

Nonetheless, military historians and researchers have been able to piece together fragmented parts of the vessel’s history to gain an understanding of what the aircraft carrier may have looked like. 

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.

Using this design, the Shinao, alongside another unnamed BB design were first drawn up in 1939, and it wasn’t long before Japanese workers began constructing this vessel.

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 during the Battle of Midway. 

According to the US Naval Institute, the plans aimed to convert Shinao “into a strong floating air base, capable of retrieving, launching, and supplying naval aircraft operating from land bases or other ships.”

At full capacity, the Shinano could carry around 47 different types of aircraft utilized by the Japanese Air Force.

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 Shinano was officially launched on October 8, 1944, and commissioned on November 19, over a month later.

The Japanese feared the US could begin bombing Japan using long-range missiles fired from bases in the Mariana Islands. 

During the floating out process, a rush of water flowed into the graving dock due to problems with one of the caissons. This pushed the carrier into the forward end and damaged its bow structure, which required repairs. Many now see this as an omen of what was to come. 

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.

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.

The Shinano exposed the entire side of the vessel, which the Archerfish capitalized on, and Enright decided to fire torpedoes toward the Japanese vessel. 

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. 

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. 

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. 

The high death toll can be attributed to several factors, much of which is ascribed to the illusion the sustained damage was manageable. Despite this, over 1,000 members of the IJN were eventually rescued. 

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.

In addition, the crew’s reluctance to rest for water tightness in several compartments before deployment played a role in failing to access potential leaks which could have been otherwise patched. 

In his report, he surmised that seawater would have filled the ship rapidly following the explosion of the torpedoes because the watertight doors were unseaworthy. 

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.