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) near Carlsbad, New Mexico, was set on fire on May 15, 1943, when armed bats were accidentally released.
The bats roosted under a fuel tank and incinerated the test range.

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.

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 mid-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 (equivalent to $19 million today) 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.
Adams maintained that the bat bombs would have been effective without the devastating effects of the atomic bomb: "Think of thousands of fires breaking out simultaneously over a circle of forty miles [64 km] in diameter for every bomb dropped.
Japan could have been devastated, yet with small loss of life."

The infamous "Invasion by Bats" project was afterwards referred to by Stanley P. Lovell, director of research and development for Office of Strategic Services (OSS), whom General Donovan ordered to review the idea, as "Die Fledermaus Farce".
Lovell also mentioned that bats during testing were dropping to the ground like stones.
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) near Carlsbad, New Mexico, was set on fire on May 15, 1943, when armed bats were accidentally released. The bats roosted under a fuel tank and incinerated the test range.
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. 
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 mid-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 (equivalent to $19 million today) 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. Adams maintained that the bat bombs would have been effective without the devastating effects of the atomic bomb: "Think of thousands of fires breaking out simultaneously over a circle of forty miles [64 km] in diameter for every bomb dropped. Japan could have been devastated, yet with small loss of life."
The infamous "Invasion by Bats" project was afterwards referred to by Stanley P. Lovell, director of research and development for Office of Strategic Services (OSS), whom General Donovan ordered to review the idea, as "Die Fledermaus Farce". Lovell also mentioned that bats during testing were dropping to the ground like stones.
Bat bomb