The Battle of the Atlantic and the Pacific Submarine Campaigns

Introduction

• Discusses the Battle of the Atlantic: German U-boats attacking Allied shipping.
• Introduces the lesser-known American submarine campaign against Japanese shipping during WWII.

U.S. Navy's Initial Stance on Submarines

• In 1930, the U.S. and Britain proposed banning submarines under the London Naval Treaty.
• Submarines weren't initially intended for attacking merchant ships.
• American submarines like the Gato and Balao classes were designed to attack enemy warships.

Shift in Strategy Post-Pearl Harbor

• After the attack on Pearl Harbor in Dec 1941, the U.S. Navy, under Admiral Harold Stark, initiated unrestricted submarine warfare against Japan.
• Japan's war economy was vulnerable due to its reliance on shipping for resources like iron, bauxite, rubber, and oil.

American Submarine Operations in 1942

• Submarines were tasked with various missions: laying mines, reconnaissance, and intercepting warships.
• Warships were difficult targets for submarines; only 4 of 23 capital ship attacks in 1942 resulted in damage.
• American submarines sank 154 merchant ships in 1942, according to post-war assessments.
• The German U-boats had more success, sinking 526 Allied ships in the Atlantic in the first half of 1942.

Challenges Faced by American Submarines

• Loss of bases like the Philippines and Guam impacted operations.
• Reliability issues with the Mark 14 torpedo; both detonators were defective.
• Leadership and strategy issues were highlighted by historian Clay Blair.

Improvements in 1943

• Rear Admiral Charles Lockwood took command, focusing more on Japanese merchant shipping.
• Increase in sinkings: 335 Japanese ships by submarines and 135 more by other causes.
• Torpedo reliability gradually improved by September 1943.

Japan's Response

• Japan created the Merchant Escort Command in late 1943 to protect its shipping.
• Japan faced shortages of destroyers and escort ships.
• Began constructing new merchant ships and escorts, but not enough to stop the decline.

American Submarine Efficiency in 1944

• U.S. submarines reached high efficiency with improved crew, torpedoes, and strategies.
• New bases in the Mariana Islands brought American forces closer to Japanese shipping lanes.
• Sinking rates increased dramatically: 548 merchant ships by submarines and 432 by other forces.

Impact on Japan's War Economy

• Japanese imports and merchant fleet size drastically reduced.
• Shortage of vital materials and fuel; attempts to extract oil from pine needles.
• By 1945, Japan's merchant fleet was largely inactive, leading to a quieter year for submarines.

Conclusion

• The campaign against Japanese merchant shipping was a major but less recognized battle of WWII.
• The decline in Japan's war economy was pivotal in the outcome of the Pacific War.
• Future stories will focus on specific events within this campaign.