There was a similar thing that happened in city. I can't remember the specifics, but it was a queen who tied burning sticks to pidgeons or **** in a city she were going to invade. The pidgeons then flew back to their nests, causing fire to erupt all over the town.
I'm pretty sure that was during WWII for use against wooden Japanese buildings, but the bats ended up setting the training facility on fire and the plan was abandoned. Pigeons seem more trainable.
You're thinking of the bat bombs designed by Lytle Adams ( en.wikipedia.org/wiki/Bat_bomb ) during the Second World War. It didn't happen because the Manhattan Project beat it out for a "quick end to the war."