Lecture Notes: Sinking of the Japanese Super Carrier Shinano

Overview

• Date of Event: November 29, 1944
• Main Event: Sinking of the 71,000-ton Japanese super carrier Shinano by the American submarine USS Archerfish.
• Significance: Largest warship sunk by a submarine during World War II.

Background

• Initial Plan: Shinano was to be the third ship in Japan's Yamato class battleships.
• Conversion: Post-Midway Battle (1942), converted to an aircraft carrier.
• Completion Deadline: Rushed to November 1944 due to deteriorating war conditions for Japan.
• Capability: Designed to host 170 aircraft, serving as a maintenance and support hub for fleet aircraft.

Launch and Initial Trials

• Date of Maiden Voyage: November 28, 1944
• Escorts: Kagaro-class Destroyers Isakaze, Hamakaze, and Yukikaze.
• Crew: Over 2,500 people including 300 civilian workers.
• Operational Concerns:
  • Only 8 of 12 boilers operational.
  • Lack of airtight compartment tests.
  • No air cover, making the journey at night to avoid submarine attacks.

Encounter with USS Archerfish

• Submarine Skipper: Commander Joseph Enright.
• Discovery: Archerfish's radar detected Shinano at 22 km.
• Tactics: Enright maneuvered into position, using radar to track Shinano.
• Japanese Response: Captain Abe underestimated the threat, anticipating a multi-submarine attack.

The Attack

• Time of Attack: Early morning, November 29, 1944.
• Submarine Speed and Positioning: Despite being slower, Archerfish positioned itself for attack.
• Number of Torpedoes Fired: 6
• Hits: 4 large explosions, breaching Shinano's starboard side.

Damage and Sinking

• Initial Damage: Severe flooding due to torpedo hits below waterline.
• Flooding: Rapid list to starboard; critical areas flooded leading to loss of control.
• Attempts to Salvage:
  • Counter-flooding efforts failed.
  • Speed reduced due to boiler shutdowns.
  • Attempted course change to beach the ship.
• Final Moments: Abandon ship order; Shinano sank at 10:55 AM.

Aftermath

• Japanese Losses: 1,455 of 2,515 onboard perished.
• Archerfish Success: Most successful U.S. submarine patrol by tonnage.
• Japanese Inquiry: Found multiple errors in judgment, quality, and luck.
• Secrecy: Loss kept secret to maintain morale.

Conclusion

• The sinking of Shinano demonstrated the vulnerabilities even of the most formidable warships when faced with submarine warfare.
• Highlights the impact of rushed construction, inadequate protection, and strategic misjudgments in wartime scenarios.