The Second World War was not enough to quench Churchill’s thirst for warfare. Within a week of Germany’s surrender, he summoned his chiefs of staff and asked them if it was possible to force the Red Army out of Germany and Poland? He told them that the offensive against the Soviet Union should take place on July 1, 1945, before the strength of the allied formations was reduced due to demobilization or transfers.
The plan to attack the Soviet Union was named Operation Unthinkable. The most explosive part of Operation Unthinkable was the instruction to Montgomery to take control of surrendered German weaponry, in case the German army was reconstituted for the new war against the Soviet Union.
Though the operation was being conducted in secrecy, one of Beria’s moles in Whitehall (probably Guy Burgess) learned about it and passed the details to Moscow. This resulted in General Zhukov putting the Red Army troops in Poland in a state of alert.
In their report on the viability of Operation Unthinkable, Churchill’s generals were blunt and clear—they noted that, even with American help, it would be difficult to defeat the Soviet Union which was now “all powerful in Europe.” The assessment, signed by the Chief of Army Staff on 9 June 1945, concluded: "It would be beyond our power to win a quick but limited success and we would be committed to a protracted war against heavy odds.”
If Churchill had not lost the general election in 1945, he might have pushed Europe into a Third World War. The labor government under Clement Attlee ignored Churchill’s plan.