Shortly after Pearl Harbor, a dental surgeon from Pennsylvania named Lytle S. Adams came up with an idea that the US military thought might have some merit: dropping napalm armed bats on Japan.

Yes, really. They spent 2 million on it.

The plan was to put the bats into hibernation, fit each bat with a payload of napalm and a small parachute, and airdrop them over Japan. President Franklin Roosevelt apparently approved this. With the help of chiroptologist Donald Griffin, the National Defence Research Committee, the NDRC, the Army's Chemical Warfare Service, and the Navy (submarines could release bats too), the plan finally reached the testing phase. On May 15, 1943, at a remote airfield in California, the first bat-drop was executed.

The bats did not come out of their refrigerator induced hibernation on cue. The parachutes weren't big enough. Most of the bats hit the ground. A few bats had better luck; they woke up before they could splatter against the ground, and, as was hoped, they flew towards the nearest buildings. If this had been in Japan, that would have been great. But as it was, the napalm set fire to the airport hangars and a general's car.

Thereafter the plan was dropped.

For a much better account read Natural Acts Wool of Bat by David Quammen