The US military spent $2 million training bats to carry napalm bombs over Japan — until escaped test bats burned down a US Army Air Forces base in New Mexico.
In January 1942, a Pennsylvania dentist named Lytle Adams wrote to the White House with a weapons proposal: strap tiny napalm bombs to thousands of hibernating bats and drop them over Japanese cities. President Roosevelt forwarded it to the OSS with the note: 'This man is not a nut. It sounds like a perfectly wild idea but is worth looking into.'
The science was surprisingly sound. Mexican free-tailed bats can carry payloads exceeding their own body weight. Each bomb canister would hold over 1,000 hibernating bats, each attached to a timed napalm incendiary. Dropped at dawn, the bats would scatter across a 20-40 mile radius and roost in building eaves before the timers fired, spreading fires across a massive area.
The inventor of napalm, Louis Fieser, was brought in to design the miniature incendiaries. Harvard zoology professor Donald Griffin joined to advise on bat behavior. The Army froze bats in ice cube trays to keep them in hibernation during transport. The program was methodically developed across multiple sites — until the bats got loose.
On May 15, 1943, at Carlsbad Army Airfield in New Mexico, a group of armed test bats escaped prematurely. They roosted beneath a fuel tank on the base itself and detonated, burning down a significant portion of the military facility — including the general's car. The test range was destroyed.
Despite the setback, advocates pushed forward. Tests at a Japanese-style 'village' mock-up at Dugway Proving Ground suggested the bat bombs could cause 3,625 to 4,748 fires per bomb load — compared to 167-400 fires from conventional incendiary bombs. The program's proponents believed it could devastate Japan at minimal human cost.
The program was cancelled in mid-1944 by Fleet Admiral Ernest King when he calculated it wouldn't be combat-ready until mid-1945 — too late. About $2 million had been spent (roughly $36 million today). Adams was furious, arguing to his dying day that bat bombs could have ended the war more humanely than the atomic bomb.