Share This Article

During World War II, the military teamed with a dentist and a Harvard scientist to arm winged creatures of the night with napalm bombs.

DR. LYTLE S. ADAMS, a Pennsylvania dentist, pilot, and inventor, heard about the Pearl Harbor attacks on his way home from a visit to the bat-filled Carlsbad Caverns in New Mexico. His mind started working. In the late 1920s, Adams patented a system for airplanes to collect mail sacks without landing by using a weighted cable and a pickup rope. He created a business—a forerunner of US Airways—and took Eleanor Roosevelt, a champion of rural reform, on a demonstration flight. In January 1942, Adams persuaded Roosevelt, now First Lady, to pass a memo to her husband.

“[The] lowest form of life is the bat, associated in history with the underworld and regions of darkness and evil,” Adams wrote to President Franklin Roosevelt. “Until now reasons for its creation have remained unexplained. As I vision it the millions of bats that have for ages inhabited our belfries, tunnels and caverns were placed there by God to await this hour to play their part in the scheme of free human existence, and to frustrate any attempt of those who dare desecrate our way of life.” A fire attack by millions of bats, he continued, “would render the Japanese people homeless and their industries useless, yet the innocent could escape with their lives.”

FDR was intrigued. “This man is not a nut,” he wrote to Office of Strategic Services director Colonel William Donovan. “It sounds like a perfectly wild idea but it is worth looking into.” After bureaucratic delays, officials assigned brilliant Harvard organic chemist Louis Fieser, fresh from his 1942 invention of napalm, to the enterprise in March 1943.

Work began on a new weapon system that would feature bats, an ancient vector for disease, bearing firebombs against Japan. Fieser designed a napalm bomb and timer that weighed just 17.5 grams. Adams recruited researchers from the Natural History Museum of Los Angeles County—he sited the program in the City of Angels because he had relatives there—and determined that the 10- to 11-gram Mexican free-tailed bat was the best suited to bomber duty: Millions migrated to Texas every summer; each could carry a 15- to 18-gram payload.

Napalm was “to be attached to hibernating bat vectors which would be flown over Japanese cities at night and parachuted down into warm air, when the bats would awaken and carry the bombs onto or into highly com bustible Japanese houses,” Fieser wrote.

Army officials scheduled a test for May 1943 at the Muroc Air Base (now Edwards Air Force Base) outside Los Angeles. A large dry lake on the base, bleached white by the sun, would, it was thought, facilitate bat recovery. Standard Pyroxoloid, in western Massachusetts, prepared 3,000 tiny bombs and filled some with napalm. Technicians at Harvard’s Gibbs Chemistry Laboratory loaded the rest with smoke-producing red phosphorus to help locate the bombs. Connecticut toy company A. C. Gilbert, famous for its Erector Set building kits, manufactured mechanical timers. An army team at Wright Field in Dayton, Ohio, built a special refrigerated truck to chill and transport hibernating bats, loaded it with napalm and timers, and drove to Los Angeles.

Fieser and two officers from the Army’s Chemical Warfare Service (CWS) arrived in Southern California on May 17, and proceeded to Adams’s home for an evening review of the top-secret operation. “We were horrified to find that Adams had invited a large company, including ladies, to a dinner party in celebration of the initiation of field tests,” Fieser recalled.

Worse, the inventor had gathered only 150 test bats, rather than the agreed 3,000. It was mating season for bats in Los Angeles and they were hard to catch, he explained.

Improvisation followed. CWS lieutenant colonel R. Bruce Epler and some of Adams’s staff made an emergency trip to Carlsbad the next morning in a B-25 bomber assigned to the project. They landed at a nearby army air base, obtained a permit from the Park Service, collected eight large crates of bats, and flew back to Muroc.

“Shortly after dinner the bomber flew in loaded with shrieking, kicking bats,” Fieser recalled. Team members packed the creatures into the refrigerated truck and turned on the cooling system full blast. When the cacophony did not diminish after a few hours, they wrapped blocks of ice in towels and tucked them in with the bats, then positioned fans in front of ice stacked around the mammals. Shrieks subsided around midnight.

Researchers planned to pack the bats into five-foot-tall bombshells filled with one-and-a-half-inch circular trays divided into bat-sized niches and stacked upside down. Hibernating bats with napalm bombs fastened to their breasts with surgical clips—thought to simulate baby bat claws—traveled in the niches.

When the shell was released, a parachute deployed, the casing fell away, and the trays separated. Engineers expected the animals to wake up as the bomb descended into warmer air, wiggle or fall out of the trays, and fly away—disconnecting safety wires and arming the bombs in the process.

Each shell could hold 1,030 bats. A B-25 could carry 25 shells: almost 26,000 bat bombs. A California company owned by entertainer Bing Crosby and his brother Larry contracted to build the bombshells.

Adams produced only cardboard mockups of the bombs for the test, however. These disintegrated as soon as staff launched them from the B-25. Fieser, for his part, hadn’t completed work on the safety mechanism for the time bombs, and the pilot refused to allow the tiny incendiaries on board. Team members clipped weights to the bats, in lieu of bombs, and threw them out of the airplane by hand. A ground crew in jeeps raced after them on the lakebed.

Adams and Fieser released an initial batch of test subjects at 2,000 feet. They plummeted straight to the ground in free fall. “Few if any of the bats had come out of hibernation,” Fieser wrote. More altitude was required to give the animals time to wake up. The pilot circled higher and higher, but results were the same. “Eventually it became clear that the bats were not in hibernation but dead,” Harvard’s genius wrote. “Instead of freezing them to hibernation, we had frozen them to death the night before.”


 PROJECT MEMBERS scheduled a second test at Carlsbad air base,  close to the bat caves. On his previous visit, Epler had noticed that a new auxiliary landing field—with control tower, barracks, offices, hangars, and outbuildings—had just been completed some distance from the main facility. He and Fieser visited the base commander. They couldn’t explain their mission, they said, but displayed orders marked “Top Secret.” The colonel agreed to delay inauguration of the field—a flight training facility he had conceived and whose construction he had supervised—for a few days.

The second effort was more successful. The researchers collected a fresh set of bats, chilled them more gently, and loaded them into a steel Crosby company shell. Fieser had not yet been able to manufacture a safety system, so dummy bombs were used again. Deployment took place with a group of observers on hand that included Marine Corps general Louis DeHaven. Epler, notwithstanding his rank as a lieutenant colonel, insisted that the base commander, a full colonel, be excluded to maintain secrecy.

A bat bomb dropped. Its parachute opened at 4,000 feet. “Soon tiny motes began to flutter across the sky, flying in all directions, most borne northward in a fluttering clump by the breeze,” recalled team member Jack Couffer, a junior chiroptologist, or bat scientist, from the Natural History Museum. Investigators leaped into jeeps and set off after the animals at high speed over rough country. They tracked a large group for miles to the barn of a rancher, rushed onto his front porch, and asked if he had noticed anything unusual. “Like bats flyin’ ’round in broad daylight? Unusual like that?” he answered.

They begged for secrecy. “I got two sons somewhere in Europe fightin’ the Hun,” the rancher said. “If you tell me that what yer doin’, however damned fool as it looks to me, is a military secret, nobody’s goin’ to get me to say a peep even by puttin’ bamboo splinters under my fingernails and alightin’ fire to ’em.” He gestured to a bat that peered down from a niche between the porch’s ceiling boards. It straddled a dummy bomb. The delivery system worked.

That would have been a good place to end the day’s research. Adams, however, wanted to confirm their results with a second test. Fieser decided to take advantage of this opportunity to demonstrate his inventiveness to Army Signal Corps photographers assigned to the trials.

Assistants handed him six torpid chilled bats with bombs attached. Their delay device used corrosive copper chloride to dissolve a trigger wire. A thicker wire produced a longer delay. Demonstration units had 15-minute wires. As the cameras whirred and clicked, Fieser ceremoniously injected chloride into one timer after another from a large steel-and-glass syringe.


 IN AN INSTANT, the mammals woke up and took off. A hot New Mexico  sun had revived them with unexpected speed. Small shapes flapped into the sky over the brand-new landing field.

Couffer explained what happened next: “Exactly 15 minutes after arming, a barracks burst into flames; minutes later the tall tower erupted into a huge candle visible for miles. Offices and hangars followed in order corresponding to the intervals between Fieser’s chemical injections.” Unfortunately, to preserve secrecy, and because the plan called for using dummy bombs, the team had eschewed fire equipment. By the time the base commander—alerted by plumes of thick black smoke—arrived with three fire engines, many structures lay in ashes. In any event, guards, under Lieutenant Colonel Epler’s command during the test, refused to unlock the gates. A heated discussion ensued, with the fire trucks and base commander outside, and Epler inside. Not only did the junior CWS officer refuse to budge, he asked the colonel for a bulldozer to raze whatever might be left of his facility after the fires burned out.

Army officials decided they wanted no further part of the project. General DeHaven, however, was impressed. Marines took over in the autumn of 1943, named the enterprise Project X-Ray, and designated the Marine Air Station at El Centro, California, as headquarters. They posted armed guards at the two largest bat caves in the United States (near San Antonio, Texas), and assigned a twin-engine Lockheed Lodestar airplane to the effort. Officers forced out Adams, whose role in the project had become increasingly tenuous.


 FROM DECEMBER 17 TO 19, Marines tested the bat bombs at replica Japanese and German villages built at the Dugway Proving Grounds in Utah. They employed due caution. Bats carried dummy bombs, now glued directly to the animals. Researchers located the beasts after they landed, and hand placed napalm bombs nearby.

Results proved positive: Despite wet wood and cold temperatures, Dugway’s chief incendiary officer concluded bats could plant bombs inside buildings, often without detection, and were very effective. Fieser, who attended the tests, determined that napalm bombardment by bat was about 3.7 times more efficient than by gravity.

Design and testing was complete by February 1944. Manufacturers and bat collection teams stood by to fulfill an expected initial order for 1 million animals, incendiaries, and timers. Then, suddenly and without definitive explanation—a historical mystery still to be resolved— the project was canceled after an expenditure of about $24 million in today’s dollars. “Uncertainties involved in the behavior of the animal,” blandly observed government chemist Harris M. Chadwell, created too many unknown variables.

Napalm had to rely on more traditional vectors to reach its targets.


Adapted from Napalm: An American Biography, by Robert M. Neer. Copyright © 2013 by Robert M. Neer. Used by permission. All rights reserved.

Originally published in the Summer 2013 issue of Military History Quarterly. To subscribe, click here.