The Japanese aircraft carrier Shinano, the largest aircraft carrier in the world at the time, was sunk on November 29, 1944, by the U.S. submarine USS Archerfish (SS-311) during its maiden voyage. Despite its size and armored protection, the Shinano never participated in World War II because of a combination of poor planning, rushed construction, and tactical errors. Below are the key reasons for its sinking:
1. Rushed Construction and Incomplete Readiness
The Shinano was originally conceived as the third Yamato-class battleship, but midway through its construction, Japan converted it into an aircraft carrier after recognizing the growing importance of naval aviation. This last-minute redesign introduced significant challenges:
The ship was launched in an unfinished state to expedite its deployment. It was only 45% complete, with many critical systems, including watertight compartments, not properly sealed.
Vital equipment, such as pumps, damage control tools, and safety measures, were either incomplete or non-operational, leaving the ship vulnerable.
2. Lack of Escort and Overconfidence
The Shinano was being transported from Yokosuka to Kure Naval Base for final outfitting. Despite its incomplete state, Japanese planners decided to send it with minimal protection, likely due to overconfidence in the ship's size and armor.
The Shinano’s escort consisted of only three destroyers, which proved insufficient to deter or detect an enemy submarine.
The decision to travel under radio silence limited coordination and increased the risk of an attack.
3. Detection by USS Archerfish
On the night of November 28, 1944, the USS Archerfish, a U.S. Navy submarine, spotted the Shinano and shadowed it for several hours. The massive carrier presented an unmissable target, and Archerfish’s captain, Commander Joseph F. Enright, successfully calculated its course and speed.
Archerfish fired six torpedoes, four of which struck Shinano on its starboard side, inflicting critical damage.
4. Fatal Design Flaws
Although the Shinano was the largest carrier of its time and heavily armored, it suffered from severe design and construction flaws:
The ship’s watertight compartments were poorly sealed or incomplete, leading to rapid flooding after the torpedo hits.
The crew, largely inexperienced, struggled to manage damage control effectively, partly due to insufficient training and inadequate equipment.
The decision to maintain high speed after the torpedo strikes worsened the flooding, accelerating the sinking process.
5. Ineffective Japanese Strategy
Japanese naval leaders were desperate to reinforce their depleted fleet and rushed the Shinano into service without ensuring its combat readiness. The gamble to move the unfinished carrier across open waters proved catastrophic, as it made the ship a vulnerable target for U.S. submarines patrolling the Pacific.
The Aftermath
The Shinano sank just seven hours after the torpedo strikes, taking with it over 1,400 crew members and construction workers. The loss of such a colossal and strategically important ship dealt a psychological blow to Japan, highlighting the nation's deteriorating industrial and naval capabilities late in the war.