In the early days of the Cold War, the British produced a secret weapon intended to stop any Soviet invasion of West Germany in its tracks.

Codenamed Blue Peacock, the weapon was a remotely triggered atomic land mine. Based on Britain’s first domestically produced atomic bomb (codenamed Blue Danube), Blue Peacock weighed 16,000 pounds and was armed with a warhead able to produce an explosion equivalent to 10,000 tons of TNT. Ten were ordered in 1957.

Blue Peacock’s size and weight made it impractical to deploy on an active battlefield, so the plan was that the ten weapons would be buried along the inter-German border if war ever appeared to be imminent. They could then be detonated remotely if war actually broke out. Detonation would create a crater hundreds of feet in diameter and irradiate terrain for miles around, making the area difficult for Soviet forces to safely cross.

However, there was a problem. The NATO allies had divided up West Germany into sectors, with each ally being responsible for the defense of a sector. Britain’s sector was North Germany, where winters can get quite cold. Engineers were concerned that in winter, sensitive components would freeze or fail in the multi-day time window between burial and intended detonation.

Various proposals were explored to solve this. One was to include a live chicken inside each Blue Peacock, with a week’s worth of food and water. The chicken’s body heat, it was argued, would keep the components above freezing point. (Until the chicken expired, anyway.)

The problem was ultimately never solved, because Blue Peacock was canceled in 1958. Not because of the thermal issues, but because British planners finally decided that planning to drench all of North Germany in radiation might potentially be taken the wrong way by their German allies.

The Blue Peacock program was held secret until mentions of it were found in newly declassified documents in 2003.

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SOURCES/FURTHER READING
https://en.wikipedia.org/wiki/Blue_Peacock
https://www.popularmechanics.com/military/weapons/a25645798/blue-peacock-land-mine/
https://www.theguardian.com/uk/2003/jul/17/world.jamiewilson
https://americandigest.org/mt-archives/bluepeacock.pdf