Pigeons and bats were both used in separate projects. You're thinking of the bat one. Incendiaries were attached to bats, who were dropped from planes. And the

Pigeons and bats were both used in separate projects. You're thinking of the bat one. Incendiaries were attached to bats, who were dropped from planes. And then expected to fly into buildings. Incendiaries go off. Building burns down. Pigeons were used as the guidance system in an early smart bomb. Rather than tracking a target with a laser or GPS, trained pigeons would steer the bomb.