Well, during WWII, the U.S. ran some tests on
this bizarre weapon, but never actually deployed it:
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https://en.wikipedia.org/wiki/Bat_bomb
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Bat bombs were an experimental World War II weapon developed by
the United States. The bomb consisted of a bomb-shaped casing with
over a thousand compartments, each containing a hibernating 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 disperse
and roost in eaves and attics in a 20–40-mile radius.
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.