He got the office in 1924, after the death of Lenin. During the 1930's Stalin was aware of the Nazi threat, but the unwillingness of France and Great Britain to make an alliance with the Soviet Union led Stalin to agree to a Russo-German Pact with Nazi Germany in August 1939. Hitler's attack on Russia in 1941 came to Stalin by surprise. But after a series of defeats the Soviets stopped the Germans at Stalingrad in February 1943. From then onwards, the Soviet Union gradually advanced towards Germany till they defeated her with the Western Allies. The sacrifices of the Russian people were enormous. Millions of Russian citizens were killed by the purges that Stalin conducted against his rivals and those suspected as rivals during his years of dictatorship. However, the Theran conference of December 1943 recognised Russia's pre-eminent political position in Eastern Europe.
