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.
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.