The idea of using "bat bombs" against Japan in retaliation for the December 1941 sneak attack on Pearl Harbor may sound ludicrous, but, for a while, President Franklin D. Roosevelt was in favor of the plan, and American military experts worked on a prototype. The theory was that a bomb casing could contain thousands of hibernating bats, each trussed up with an incendiary device and a timer. If all went as planned, countless Mexican free-tailed bats would be released over Japanese cities, eventually roosting in eaves and attics and starting thousands of small fires.
An invasion of bat bombers:
- Lytle S. Adams, a Pennsylvania dentist who was an acquaintance of First Lady Eleanor Roosevelt, proposed the idea in January 1942 after a vacation to New Mexico, where he learned about bats in Carlsbad Caverns.
- The idea, later known as Project X-Ray, was seriously considered. Louis Fieser, the inventor of military napalm, designed small incendiary devices for the bats to carry.
- After numerous tests over several years, at a cost of about $2 million USD, it was determined that the bat bombs would not be ready until the middle of 1945. By that time, the atomic bomb was deemed to be a more expedient option in bringing about the end of the war.