The Bat Bombers of World War II

Structure set on fire by a bat bomb.

Structure set on fire by a bat bomb.

Something about war brings out the creative side in people. Combatants constantly try to get the leg up over their enemy, but sometimes that spirit of trying to outdo the other guy takes people down weird bunny trails. World War II hosted some of the perhaps weirdest tech ever tried during combat. While the Nazis cornered the market on weird weaponry, the US had its fair share of strange ideas. One of the oddest was, in true democratic fashion, suggested by a citizen rather than a soldier. He was Dr. Lytle S. Adams, a dental surgeon from Pennsylvania. His suggestion, inspired by a visit to Carlsbad Caverns, was to put America’s vast swarms of bats to work destroying Japan’s cities.


Animal warfare

While the idea of using animals to wreak havoc during a modern war characterized by huge aerial armadas and swarms of tanks, animals have taken part in human warfare for as long as people have tried to kill one another in elaborate and ridiculous ways. Horses of course are the best known war animals, playing a pivotal role in almost every battle since they were domesticated, including important roles in World War II, where they were used to transport supplies along roads impassible to motor vehicles. Dogs were used to hunt down fleeing foes, to guard camps, and occasionally to break up enemy formations.

Bats, however, never really played a role in warfare. Given that they’re small animals who aren’t able to be trained like, say, a dog, rather put them out of the running when it came time for choosing fighting creatures. But Dr. Adams’ idea wouldn’t require the bats to do anything more than act natural. He envisioned thousands of bats being dropped from bomb canisters. With small incendiary bombs attached to them, they would fly to available cracks and crevices to roost. The incendiaries would be fitted with timers, and would eventually detonated and start a fire. Many Japanese buildings were constructed out of wood, and thousands and thousands of fires started within moments of each other would devastate huge swaths of a city.

Weird as the plan was, it got approval, not in small part because Dr. Adams was acquainted with Eleanor Roosevelt, wife of the then President Franklin Delano Roosevelt. Dr. Adams demonstrated his unique weapon’s system first in Washington, showing Army officials that they could be outfitted with a dummy bomb. The project was approved in March of 1943. The bat used was the free-tail bat. Not overly large, the mighty mammal could carry three times its tiny weight. Which still was tiny, although small incendiaries were not difficult to design and researchers whipped up two varieties—a seventeen gram bomb that would burn for four minutes, and a twenty-eight gram bomb that would burn for six minutes. In addition, dummy weapons that would release yellow smoke for thirty minutes. These were to be used during testing.

Delivering the biological bombs was an entirely different issue. Bats were stored in refrigerated units or ice boxes to induce them to hibernate. These hibernating bats would be dropped from specially designed canisters that would open up and allow the bats to escape as they warmed up and began to wake. Then the bats would fly away from the canister and fulfill their deadly duty.


Project canceled

Canister used to transport the bats.

Canister used to transport the bats.

However, it was soon apparent that the scheme was more complicated than it appeared. Bats often didn’t wake in time once dropped from the plane. The delivery system didn’t work properly, and the bombs proved hard to attach to the bats. The Army found that the bats could carry the smaller bombs comfortably. The bats who did survive the tests were found with their bombs nestled in houses built on the testing grounds.

The Army concluded that a better delivery system for the bats was needed. Also, a new way to attach the bombs to the bats and a better time-delay fuse was needed. Another recommendation was made to study how bats behave during artificial hibernation.

Still, the test was pretty successful. Surprisingly so. A mock Japanese village was burn to the ground by the hapless bats. In one instance, which possibly had something to do with canceling the project, a careless handler let several bats armed with live bombs escape. They proceeded to burn down a hangar and a general’s car.

The Army passed the project to the navy in August 1943, which dubbed it X-Ray. In October of that year, the Navy leased four caves in Texas and began harvesting bats for testing. They promptly handed the project to the Marines, who began experimentation in December 1943. The Marine tests proved promising—one test started thirty fires, eight of which would have required the efforts of firefighters to put out. The Marines deemed that a more powerful bomb was needed, and plans for full-scale tests were drawn up for August 1944.

But these plans would never be enacted. Fleet Admiral Ernest J King canceled the project when he found out the bats would not be ready until mid-1945. By that time $2 million had been spent on the project. That money could be better spent elsewhere. And so one of the weirdest projects of the war was canceled, ending the free-tail bat’s brief tour of service in the US military.



Madrigal, Alexis C. “Old, Weird Tech: The Bat Bombs of World War II.” April 14, 2011. The Atlantic. August 20, 2014.