The Mexican free-tail bat is an unlikely warrior, but the…

The Mexican free-tail bat is an unlikely warrior, but the Adams Plan was to release millions of them over Japan carrying twice their weight in incendiaries to start fires. (DoD Photo)

Any new idea will have an evolutionary, developmental phase and this inevitably includes humorous incidents, especially when the plan involves using millions of bats to carry incendiaries to the enemy heartland—the American “Bat Bomb” project, AKA “Project X-Ray.”

The idea sounded like it might work as a weapon-deployment system, because, although small, bats can carry more than their weight in cargo; mothers carry their young, and twins are not uncommon. Bats predictably hibernate when the temperature drops and do not require food or care then. They are nocturnal, as their prey is nocturnal; about dawn they find secluded places to hide or hang—above ground—as they must drop to get air in their wings to fly. If buildings are present, they like eaves or open attics. And there are plenty of bats to work with.

Project Inception
The concept of bats as weapon carriers came from dental surgeon Dr. Lytle S. Adams, an acquaintance of Eleanor Roosevelt, who took the idea to Eleanor in January 1942. She took it to Franklin. FDR took it, with written assurance that Adams was no nut, to Colonel Bill Donovan, then the Coordinator of Information, who passed it to the NDRC (National Defense Research Committee), then a diversified skunkworks for the war effort. It was dubbed the “Adams Plan” and work proceeded under NDRC’s Division 19. Not all involved were enthusiastic; the NDRC’s Dr. Stanley Lovell did not speak kindly of the project in his memoirs, calling it “Die Fledermaus Farce.”

NDRC special research assistant Donald R. Griffin critiqued the proposal and noted that, “this proposal seems bizarre and visionary at first glance [but] extensive experience with experimental biology convinces the writer that if executed competently, it would have every chance of success.” He recommended the premise be explored by the Army Air Forces “with all possible speed, accuracy and efficiency.” Bomb development was given to the Chemical Warfare Service, not enthused until officials got a formal memo from USAAF in March 1943.

Nine-Gram Bomber
By then, investigators led by Adams had selected Mexican free-tail bats, based on their availability, hardiness, and load ability of twice their own weight. The 9-gram bats carried 17-gram incendiary devices with aplomb. CWS’ Louis Fieser at Edgewood Arsenal, inventor of napalm, developed a thickened kerosene incendiary carried in a nitrocellulose canister, initiated by a miniature time pencil. It would burn four minutes with a 10-inch flame. An alternate design weighed 22 grams and would burn for six minutes with a 12-inch flame, but was too heavy a load for a wee bat. The incendiary was fixed to the loose skin on the bat’s chest with a surgical clip and string.

Adams’ team first investigated the mastiff bat, North America’s largest flying mammal, with a 22-inch wingspan that could carry a 1-pound stick of dynamite, but they are relatively hard to find. The largest colony of free-tails found during the search was an estimated 20 to 30 million native to the Ney and Bracken limestone caves near Bandera, Texas. As a practical matter, test specimens were collected at the handier Carlsbad Caverns.

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