Dropped from a bomber at dawn, the casings would deploy a parachute in mid-flight and open to release the bats, which would then disperse and roost in eaves and attics in a 20–40-mile radius (32–64 km).

The incendiaries, which were set on timers, would then ignite and start fires in inaccessible places in the largely wood and paper constructions of the Japanese cities that were the weapon's intended target.

The bat bomb was conceived by Lytle S. Adams (1881–1970[1]), a dental surgeon from Irwin, Pennsylvania,[2] who was an acquaintance of First Lady Eleanor Roosevelt.

Adams wrote about his idea of incendiary bats in a letter to the White House in January 1942—little more than a month after the attack on Pearl Harbor.

[7] In his letter, Adams stated that the bat was the "lowest form of animal life", and that, until now, "reasons for its creation have remained unexplained".

[4]: 6  He went on to espouse that bats were created "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.

Adams assembled the workers for the project, including the mammalogist Jack von Bloeker, actor Tim Holt, a former gangster, and a former hotel manager, among others.

[2] The team had to determine several variables to make the project feasible, including what kind of incendiaries could be attached to the bats, as well as the temperatures at which to store and transport them.

Adams had to ask for permission from the National Park Service to harvest large numbers of Mexican free-tailed bats from caves on government property.

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.

"[6] The infamous "Invasion by Bats" project was afterwards referred to by Stanley P. Lovell, director of research and development for Office of Strategic Services, whom General William J. Donovan ordered to review the idea, as "Die Fledermaus Farce".