In the spring of 1945, Winston Churchill asked his military chiefs to prepare a secret plan.
That was nothing new. The hyper-energetic Churchill was always coming up with plans, some clever and some crazy. But this plan was beyond all that.
Winston Churchill wanted a plan for Britain to invade the Soviet Union.
In early 1945, America was focused on finishing off Germany and then taking down Japan. But Churchill's gaze beheld a darkness descending upon Europe. What would happen with a Red Army occupying its heart? Stalin had already reneged on earlier agreements that Poland—the reason that Britain had gone to war in 1939—would be free. Instead the Polish government was packed with Soviet supporters while Polish resistance fighters ended up in NKVD prisons. Romania, Hungary and Czechoslovakia were under Soviet control, and Greece and Turkey appeared under threat. After Germany's inevitable surrender, the huge U.S. force in Europe would move to the Pacific.
Who would be left to stop the Russians?
Thus British planners devised “Operation Unthinkable,” an apt name for what would have been World War III. What could be a more unimaginable task then trying to devise some way for Britain—broke and exhausted after two world wars—from launching a preventive war to defeat the Soviet colossus?
Yet even if Great Britain was losing the “Great” by 1945, orders were orders, and military planners are accustomed to devising responses to the most unlikely contingencies. So they gamely went to work, and by 1945 had worked out a plan. The attack would begin on July 1, 1945, to allow operations before the winter weather arrived. They assumed that Soviet intelligence would detect Allied preparations and thus make an Operation Barbarossa–style surprise offensive impossible. Thus the Allies would have a tough fight right from the start.
Operation Unthinkable envisioned an offensive by the Anglo-American armies, plus a Free Polish contingent (the Canadians were also informed of the plan). These forces would breach the forward Soviet defenses in Germany. The expectation was that the Soviets would then mass their armor along the Oder and Neisse rivers, which the Soviets had made the new border between Germany and Poland. A gigantic Kursk-like armored battle would be fought around Stettin. If the Allies won it, they would advance to a 250-mile-long line between Danzig and Breslau, where they would halt to avoid exposing their flank to a southern attack from Soviet forces in Czechoslovakia.
Ironically, the plan bore many resemblances to Hitler’s Operation Barbarossa, which also counted on defeating Soviet forces near the Russian border to avoid a prolonged campaign deep inside that vast nation. “The planners believed that if they could secure this line from Danzig to Breslau by autumn 1945, it might be enough to bring Stalin to heel,” writes author Jonathan Walker in his book Churchill's Third World War: British Plans to Attack the Soviet Empire, 1945 . “But if the Allies reached that line by the autumn (discounting the huge advantage the Soviets held in manpower) and Stalin had not changed his mind about control of Eastern Europe—what then? With the forces available to them, Western commanders could not hold their line through the winter of 1945–46 and they would be forced either to retreat or push on into eastern Poland and the Soviet Union. Pushing on would undoubtedly result in ‘total war.’”
Total war against Russia—months before the first atomic bomb was dropped on Japan—was an outcome that no one wanted. The Allied forces had nearly 4 million men in Europe when Germany surrendered, the majority of which were Americans who would soon be transferred to the Pacific. The Red Army had almost 11 million men, and perhaps 20,000 tanks and self-propelled guns. To be sure, the Allies did count on the same advantages that enabled them to defeat Nazi Germany. They had vast superiority at sea, which meant their fleets could provide amphibious support in the Baltic Sea. The Allied tactical air forces would be outnumbered two to one by Soviet tactical air, but the Allies could count on better-trained pilots and the fact that the Soviets depended on the United States for high-octane aviation fuel. However, the real ace in the air would be the 2,500 Allied heavy bombers in Europe, which presumably would include B-29s. The Luftwaffe hadn’t been able to stop them, and the Red Air Force had no experience in stopping them.
Nonetheless, the Allied planners found themselves in the same trap that destroyed Napoleon and Hitler. How do you make Russia surrender if it doesn't want to? If defeating the Red Army on German soil wasn't enough, then the only alternative was to advance eastwards into Poland and then Russia. “The planners now paled at the thought of the enormous distances the Allies would have to penetrate to secure victory,” Walker notes.