Despite European attempts at appeasing Hitler, Nazi Germany continues its war preparations. Stalin, in an attempt to buy time for the Soviet Union, signs a non-aggression pact with Berlin on August 23, 1939.

German troops storm into Poland just over a week later, starting World War II. Soviet forces take over the Baltic states and invade Finland. Stalin's treaty serves to keep Moscow out of the greater war, while the Nazis conquer much of Western Europe.

But Hitler's appetite for territory isn't sated. The Nazi invasion of the Soviet Union, "Operation Barbarossa," takes the Soviet military by surprise.

After months of retreats and millions of casualties, the Red Army begins to beat back the German forces. The costly Soviet victory during the Battle of Stalingrad in 1943 ends the German advance and signals the beginning of the end for the Nazis.
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