Explanation: In the final days of WW2, the Conservative British Prime Minister Winston Churchill proposed that the Allies don’t stop at Germany… and instead roll over the entirety of Eastern Europe, ideally overthrowing the Soviet Union itself in the process.

… fucking no one was onboard with this. Other than the spirit of optimism about the SovUnion keeping its promises regarding free and fair elections in Eastern Europe (it would not), the prospect of starting World War fucking 3 moments after WW2, and with a polity they had spent the past 4 years supplying and supporting was unpalatable to even the most vicious anti-Communists. Churchill insisted on plans being drawn up anyway - which were labeled, appropriately, "Operation Unthinkable" wherein the analysis boiled down to “If we make a sudden surprise strike with the Americans and also free a huge number of Nazi war prisoners to fight on our side… maybe it will be a winnable, brutal, protracted war.”

Neither the Americans nor the British military were onboard with this lunacy, and so the plan was filed away until it was declassified at the end of the Cold War.