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USAAF Bat-bomb canister later used to house the hibernating bats. Ideally, the canister would be dropped from high altitude over the target area, and as the bomb fell (slowed by a parachute), the bats would warm up and awaken. At 1,000 ft. altitude, the bomb would open and over a thousand bats, each carrying a tiny time-delayed napalm incendiary device, would fly in a 20–40 mile radius and roost in flammable wooden Japanese buildings. The napalm devices would ignite simultaneously, and thousands of small fires would flare up at once.

Bat bombs were an experimental World War II weapon developed by the United States. The bomb consisted of a bomb-shaped casing with numerous compartments, each containing a Mexican Free-tailed Bat with a small timed incendiary bomb attached. Dropped from a bomber at dawn, the casings would deploy a parachute in mid-flight and open to release the bats which would then roost in eaves and attics. The incendiaries would start fires in inaccessible places in the largely wood and paper construction of the Japanese cities that were the weapon's intended target.


The Bat Bomb was originally conceived by a Pennsylvania dentist named Lytle S. Adams, who happened to be a friend of First Lady Eleanor Roosevelt.[1] Dr. Adams submitted it to the White House in January 1942, where it was subsequently approved by President Roosevelt[2] on the advice of Donald Griffin.[3]

Dr. Adams observed that the infrastructure of Japan was especially susceptible to incendiary devices as many of the buildings were made of paper, bamboo, and other highly flammable material. The plan was to release bat bombs over Japanese cities having widely-dispersed industrial targets. The bats would spread far from the point of release due to the relatively high altitude of their release, then at dawn they would hide in buildings across the city. Shortly thereafter built-in timers would ignite the bombs, causing widespread fires and chaos.

The United States decided to develop the Bat Bomb during World War II as four biological factors gave promise to this plan. First, bats occur in large numbers (four caves in Texas are each occupied by several million bats). Second, bats can carry more than their own weight in flight (females carry their young—sometimes twins). Third, bats hibernate, and while dormant they do not require food or maintenance. Fourth, bats fly in darkness, then find secluded places (often in buildings) to hide during daylight.

Project details[]

Errant bats from the experimental Bat Bomb set the Carlsbad Army Airfield Auxiliary Air Base, New Mexico on fire

By March 1943 a suitable species had been selected. The project was considered serious enough that Louis Fieser, the inventor of military napalm, designed 0.6 ounce (17 g) and one ounce (28 g) incendiary devices to be carried by the bats. A bat carrier similar to a bomb casing was designed that included 26 stacked trays, each containing compartments for 40 bats. The carriers would be dropped from 5,000 feet (1,525 m). Then the trays would separate but remain connected to a parachute that would deploy at 1,000 feet (305 m). It was envisioned that ten B-24 bombers flying from Alaska, each carrying a hundred shells packed with bomb-carrying bats could release 1,040,000 bat bombs over the target—the industrial cities of Osaka Bay. A series of tests to answer various operational questions were conducted. In one incident the Carlsbad Army Airfield Auxiliary Air Base 32°15′39″N 104°13′45″W / 32.26083°N 104.22917°W / 32.26083; -104.22917 near Carlsbad, New Mexico, was set on fire on May 15, 1943, when armed bats were accidentally released.[4] The bats incinerated the test range and roosted under a fuel tank. Following this setback, the project was relegated to the Navy in August 1943, who renamed it Project X-Ray, and then passed it to the Marine Corps that December. The Marine Corps moved operations to the Marine Corps Air Station at El Centro, California. After several experiments and operational adjustments, the definitive test was carried out on the "Japanese Village" a mockup of a Japanese city built by the Chemical Warfare Service at their Dugway Proving Grounds test site in Utah.

Observers at this test produced optimistic accounts. The chief of incendiary testing at Dugway wrote: “A reasonable number of destructive fires can be started in spite of the extremely small size of the units. The main advantage of the units would seem to be their placement within the enemy structures without the knowledge of the householder or fire watchers, thus allowing the fire to establish itself before being discovered.”[1] The National Defense Research Committee (NDRC) observer stated: “It was concluded that X-Ray is an effective weapon.” The Chief Chemist’s report stated that on a weight basis X-Ray was more effective than the standard incendiary bombs in use at the time. “Expressed in another way, the regular bombs would give probably 167 to 400 fires per bomb load where X-Ray would give 3,625 to 4,748 fires”.

More tests were scheduled for the summer of 1944 but the program was cancelled by Fleet Admiral Ernest J. King when he heard that it would likely not be combat ready until mid-1945. By that time it was estimated that $2 million had been spent on the project. It is thought that development of the bat bomb was moving too slowly, and was overtaken in the race for a quick end to the war by the atomic bomb project.

Dr. Adams maintained that the bat bombs would have been effective without the devastating effects of the atomic bomb. He is quoted as having said:

Think of thousands of fires breaking out simultaneously over a circle of forty miles in diameter for every bomb dropped.

Japan could have been devastated, yet with small loss of life.[2]

The infamous "Invasion by Bats" project was afterwards referred to by Dr. Stanley P. Lovell, director of the Office of Strategic Services (OSS) as "Die Fledermaus Farce."

Cultural influence[]

  • The book Sunwing written by Kenneth Oppel was inspired by this plan.
  • The song "The Story Of The Japanese Bat Bomb" from the 2008 LP Doris, Buzz and Friends, written by John Krane, is also based on this plan, though it projects that its inventor was saddened by the bombs imminent detonation (there is no evidence of such conflict).
  • Adams and his bat bomb project are the subject of Derrick C. Brown's poem, "The Project Known as X-Ray," collected in Scandalabra.
  • Alan Scott's novel The Anthrax Mutation (original title, Project Dracula) used the "Bat Bomb" concept, but had the bats carrying volatile pouches full of powdered anthrax bacilli—a genetically-engineered strain of anthrax made to be very infective and very resistant to the effects of sunlight and temperature. The pouches fall free of the bomb casing and disintegrate once free of the low-oxygen environment inside the bomb; once in the air, the bats fly free and find niches to sleep in during the day, presumably in homes and offices.

See also[]


  1. 1.0 1.1
  2. 2.0 2.1 The Bat Bombers C. V. Glines, Air Force Magazine: Journal of the Airforce Association, October 1990, Vol. 73, No. 10. Retrieved 1 October 2006.
  3. Drumm, Patrick; Christopher Ovre (April 2011). "A batman to the rescue". p. 24. Retrieved 31 October 2013. 
  4. Steve Silverman, Einstein's Refrigerator: And Other Stories from the Flip Side of History (Andrews McMeel Publishing, 2001) p122
  • Bat Bomb: World War II's Other Secret Weapon, by Jack Couffer, University of Texas Press, 1992, ISBN 0-292-70790-8
  • "Weird Weapons: The Allies". Modern Marvels. History Channel. 2006-02-08. 
  • Lovell, Stanley P (1964). Of spies & stratagems. Pocket Books. ASIN B0007ESKHE. 
  • Spy Gadgetry: Espionage Equipment Designed to Fight Hitler, by Alan Lance Andersen, GAMES Magazine, April 2000.
  • Scott, Alan (1976). The Anthrax Mutation. Pyramid Books. ASIN B000R80FMI. ISBN 0515039497. 

External links[]

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