Nazi Germany was defeated largely – though not solely – by the Soviet Union.
But what if Nazi Germany and the Soviet Union had been allies instead of enemies? What if America, Britain, and their allies had faced a massive Red Army backed by the military prowess and technological sophistication of the Luftwaffe, Nazi panzers and U-boats?
That apocalyptic vision of a new Dark Ages almost happened. In the early days of World War II, Britain and France planned to bomb Russian oil fields. The goal was to impede Hitler. The outcome would probably have helped Hitler win the war.
The idea was foolish, but not irrational. By late 1939, Britain and France were convinced that Germany and Russia were already friends. Stalin had tried hard to form an anti-Nazi coalition before the war, only to meet such resistance and hesitation that he became convinced that the capitalists were plotting to embroil Germany and Russia in a mutually exhausting war while the West stayed on the sidelines.
While London and Paris dithered over whether to ally with the Communists, Berlin had no such hesitation: on August 23, 1939, Germany and Russia signed the Molotov-Ribbentrop Pact. Russia gained Eastern Poland and the Baltic states, a prospective breathing space to build up its military strength, and the prospect that Germany and the Western powers would exhaust themselves while Russia bided its strength.
Yet the real winner was the Fuhrer. The treaty left the Third Reich free to gobble up Poland and Western Europe without fear of a second front in the East. Just as important, the Soviets agreed to supply vital raw materials – especially oil – to the Third Reich, keeping the German war economy running and breaching the Allied naval blockade that had proved so decisive in World War I.