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The Congressman Who Accidentally Told Japan How to Sink American Submarines During WWII

In 1943 Congressman Andrew J. May unintentionally revealed that Japanese depth charges were set too shallow for U.S. submarines, which could dive well beyond 200 feet. The disclosure prompted the Imperial Japanese Navy to deepen charge settings to around 250 feet, exposing American subs to greater danger. Admiral Charles A. Lockwood later estimated the leak cost roughly ten submarines and 800 crewmen, about one‑fifth of all U.S. submarine losses. The episode, known as the May Incident, became a cautionary tale about operational‑security breaches.