In October 1944, during World War II, the Japanese aircraft carrier Shinano was sunk by the U.S. Navy submarine USS Archerfish, marking a significant event in naval warfare history. Originally designed as a Yamato-class battleship, the Shinano was hastily converted into an aircraft carrier just months before its commissioning, without sufficient testing or time for proper verification. This rushed conversion led to structural weaknesses that ultimately played a key role in its sinking. The USS Archerfish, a Balao-class submarine commanded by Lieutenant Commander Joseph F. Enright, launched six torpedoes at the Shinano. Four of these struck the ship at a critical junction between the torpedo bulkhead and the armored belt—a section that had not been adequately reinforced. This structural weakness caused rapid flooding, overwhelming the ship's systems and leading to its eventual sinking within seven hours. The Shinano’s crew and survivors reported that the ship’s compartmentation system—designed to contain flooding—failed to function as intended. This failure led to a cascade of problems, including further flooding and loss of stability. The ship’s large size, combined with these design flaws, inexperienced crew, and untested systems, made it particularly vulnerable to the attack. The sinking of the Shinano remains notable as it was the largest warship ever sunk by a submarine. It was also the largest aircraft carrier ever built until the USS Forrestal was launched in 1954. The incident highlights the consequences of rushed military construction and inadequate preparation, and it was not attributed to bad luck or natural disasters, but rather to a combination of design flaws and operational shortcomings.