During the Cold War, the British Military planned to deploy a series of nuclear landmines to protect them from the Soviets in the event of a retreat from Germany. Problem was, the mines tended to freeze up in the winter, rendering them useless. The solution? Chickens. Lots of chickens.
The plan, codenamed "Blue Peacock," was to either bury or submerge a bunch of nuclear weapons around West Germany. Each nuke would weigh seven tons and be about the size of a small truck. They could be detonated remotely, and the resulting 10 kiloton blast would leave a crater 600 feet in diameter while contaminating a much larger area with radiation. Sounds good so far, right?
However, testing revealed that the electronics inside the weapon's casing would get too cold to function reliably during the winter. The military tried to solve the problem with insulating blankets, but what they really needed was a way to generate a small but stable amount of heat inside the nuke itself, to keep everything running smoothly.
Enter the chicken.
According to declassified plans, the casing of the Blue Peacock nukes would be filled ("filled") with live chickens, along with enough food and water to keep them alive, if not exactly happy, for as long as possible. Eventually, the chickens would starve, suffocate, or become the first casualties of WWIII, but in the meantime they'd generate enough body heat to keep all of the electronics inside the bomb toasty warm. Genius.
The British Army ordered ten of the Blue Peacock weapons in 1957, but ultimately decided not to deploy them for political reasons, much to the relief of chickens everywhere.