“Bat Bombs”, the absurd story of the US lethal weapon to take revenge on Japan

Among the many absurd projects of the Second World War, one stands out for its inventiveness: that of bat bombthe “bat bomb”, designed to inflict maximum damage on the Japanese enemy's largest city, Tokyo, as revenge for the attack on Pearl Harbor. As absurd as it may seem, the Project X-Ray – official name of bat bomb – planned to drop thousands of bats carrying capsules of napalm on the wooden houses of the Japanese capital, causing indomitable fires. In the 1940s the weapon was developed and tested, costing over 2 million dollars of the time. Despite the demonstrated effectiveness of the bat bomb, in the same years work was being done on a much more lethal project, that of the atomic bomb developed by the Manhattan Project, and for this very reason the bat bomb it was set aside at the beginning of '45.

The story of the “bat bomb”: US revenge against Japan

As absurd as it may seem, the initial idea came from a dental surgeon, Lytle S. Adams, who lived in Pennsylvania. The 7 December 1941the doctor was on holiday at Carlsbad Caverns (New Mexico), which were packed with bats. Adams was so fascinated by seeing these small winged mammals that he asked himself: why not use them as a weapon against the Japanese? In fact, he thought that if each of those bats had been equipped with a small incendiary bomb they could have slipped into the ravines of some Japanese city and started a devastating fire. So it was that the doctor returned to the caves and captured some specimens, and once home he studied everything he could about those small animals. So it was that in less than a month he planned his revenge plan against the bitter enemy overseas, who had attacked Pearl Harbor on the very day Adams visited the caves.

Attack on Pearl Harbor, December 7, 1941.

Proposals for revenge multiplied on the American president's desk Franklin Delano Roosevelt, but it was the surgeon's thought that attracted attention before all the others. As luck would have it, Adams was a friend of the First Lady Eleanor Roosevelt, and when he presented his “bat bomb” to the White House in January 1942 it immediately aroused a lot of interest. In the plan document, he wrote:

Think of thousands of fires breaking out simultaneously in a circle 40 miles in diameter for every bomb dropped. Japan could emerge devastated, but with little loss of life.

There was no shortage of dirty looks from some bureaucrats. Moreover, the idea seemed very complicated to implement compared to what was indicated on paper. The president, however, believed that the project was valid, and the proposal was accepted by the National Committee for Defense Research, which dealt with ideas applicable in war.

The project was sent to Donald Griffina well-known American zoologist who discovered theecholocation in bats, the navigation system that also records frequencies inaudible to the human ear. In fact, these animals emit sounds and listen to the echoes that bounce back from what surrounds them. Echoes are therefore used to locate and estimate the distance to objects, other animals and any obstacles with great precision. Griffin immediately thought that the idea of ​​using these animals was brilliant, because the bats would fit perfectly into homes.

After a series of tests on various types of bats, the scientist suggested using the species Tadarida brasiliensisthe Mexican free-tailed bat, perfect for supporting explosive weight without too many complications.

Exemplary of Tadarida brasiliensis.

The bat bomb project: how it worked and how it was made

There were so many variables to consider, and the team of engineers and scientists under the authority of the US Air Force had to rack their brains for a few months. Which type of incendiary bombs to choose? At what temperature should bats be stored and how should they be transported? How to build the bomb that would contain them inside?

To keep the poor little animals at bay, all that could be done was to let them go inside hibernation during the trip. To do this, they were placed in large ice cube trays and “cooled” to a temperature that put them to sleep.

As regards the incendiary part, however, initially the idea was to arm the bats with white phosphorusbut then the chemist Louis Fieser was added to the team and the first option was put aside to use his invention, the napalm. Being a “gelatinous” gasoline, it was much safer to handle and burned cooler than white phosphorus. As if that wasn't enough, it was highly volatile, so it was perfect for the plan. Each bat would have carried about 15 grams inside a small cellulose container calledUnit H-2”, attached to the front of the body with a high-strength adhesive.

Napalm, The bomb carrier, instead, it was a sheet metal tube one and a half meters long, inside which there were 26 circular trays, each with a diameter of 76 centimetres. In a single bomb holder they could fit up to 1040 bats. Once dropped by a North American B-25 or a Piper L-4 Cub, the bomb carrier fell and released a parachute that slowed its descent. Meanwhile, its sides would open in all directions, allowing the small winged mammals to emerge from the trays, spread their wings and disperse into the enemy city for a maximum radius of 30 to 60 kilometers.

Adams loads a bomb rack
Dr. Adams loading a bomb rack with bats.

The technical problems and the end of Project X-Ray: the rise and fall of the project

The first official test of the “Adams Plan” (as the project was initially called by those who worked on it) was conducted in May '43 in Muroc, California (Mojave Desert). The experiment was literally… a blast. The B-52 bomber soared into the air and at 1500 meters above sea level released the bomb carriers, which contained 35,000 hibernating bats. The poor animals, still semi-frozen, were crushed to the ground.

The second attempt, in New Mexico, went partially well: the bats were released into the air with bats dummy bombs attacked, and half of them (those who didn't crash) scattered everywhere. The search party scoured the area to try to track them all down, and they were found roosting in gutters and in barns miles away from the drop zone.

The third test, in an area close to the previous one, instead involved the use of real incendiary bombs, but it went very badly due to some calculation errors. Fieser thought of attaching the bombs to the bodies of the small nocturnal animals while they were lying on a table while they were still cold. Due to the heat of that day and the timer set by Fieser for 10 minutes from release, the bats woke up earlier than expected and there were six of them roosting on the eaves of the buildings of theCarlsbad Auxiliary Airfield. They were enough to generate a fire that incinerated the air base and the car of a general, who went into a rage when he discovered it.

Being the Adams Plan top secretthe police couldn't even enter, and the military had no choice but to observe the flames.

The Carlsbad Auxiliary Airfield disaster. Credits: United States Army Air Forces.

Shortly after this fact, in August '43 the project was relegated to the Marine Corps, which called it “Project X-Ray and made the decisive test, recreating a completely realistic Japanese city in Utah to observe the effects. Indeed, the fake town of Japanese-style houses made of wood and paper it burned as expected, and the chemists who worked on the project confidently stated that this weapon was far more effective than the classic incendiary bombs of the time. Chemists who worked on the project claimed that Project X-Ray firebombs were much more effective than standard firebombs of the time. Normal bombs in fact gave approximately 167 to 400 fires per bomb load, while X-Ray could reach up to 4,748 fires.

In total it is estimated that for the bat bomb the American government has spent 2 million dollars at the time (today it would correspond to 30 million dollars). Despite all the efforts and demonstrations, however, the project was canceled in the early months of '44 in favor of the atomic bomb. With all due respect to the bats!