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Soviet Union admitted to League of Nations.
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Soviet leader Josef Stalin begins a purge of Red Army generals.
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Nazis and Soviet Union sign Non-Aggression Pact in Moscow, dividing control over Eastern Europe.
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Soviet Union attacks Finland. Russian-Finnish war, which ended around 1940 with Finland ceding territory to the USSR.
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Soviet Union retakes part of Poland that later becomes Western Ukraine and Western Belarus. Attacks occur near Vilnius and Bialystok. It was then divided between Germany and the USSR.
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The Soviet Union forces Romania to cede the eastern province of Bessarabia and the northern half of Bukovina to the Soviet Ukraine.
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The Soviet Union announces Lithuania, Latvia and Estonia as part of the USSR.
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Soviet Union and Japan sign a non-aggression pact. Japan nor the USSR wanted a two-front war, and each saw the other front as primary and paramount.
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Germany attacks Soviet Union as Operation Barbarossa begins. By the end of the year, Germany occupies Belarus and most of Ukraine, surrounds Leningrad.
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Soviet troops counterattack, breaking through the Hungarian and Romanian lines northwest and southwest of Stalingrad and trapping the German Sixth Army in the city. Forbidden by Hitler to retreat or try to break out of the Soviet ring, the survivors of the Sixth Army surrender on January 30 and February 2, 1943.
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Germans fail to take Stalingrad. A German army of over 250,000 men has been destroyed.
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The Germans launch a massive tank offensive near Kursk in the Soviet Union. The Soviets blunt the attack within a week and begin an offensive initiative of their own.
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The Soviets launch a massive offensive in eastern Byelorussia (Belarus), destroying the German Army Group Center and driving westward to the Vistula River across from Warsaw in central Poland by August 1.
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Soviet Union and the Allies reach understanding on postwar spheres of influence in Europe during the Yalta and Postdam summit conferences.
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Soviet troops begin their final attack on Berlin.
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Germany surrenders to the Soviets.
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The Soviet Union declares war on Japan and invades Manchuria.
