World War II: Blitzkrieg
World War II in Europe from the fall of Poland to Stalingrad (11 March 1940)
Historical Map of Europe & the Mediterranean
On September 17, the Soviet Union moved to occupy eastern Poland as had been agreed with Germany. The Soviets followed this by establishing influence over the Baltic states and attempting to invade Finland. Finnish defences were unexpectedly tough, however, and the Russians were forced to make do with territorial concessions.
Soviet Invasion of Poland
In accordance with the Molotov-Ribbentrop Pact, the Soviet Union invaded Poland on 17 September, meeting the Germans invading from the west on 6 October. On 1 November, the Soviets annexed Eastern Poland, incorporating its territory into the Belarusian and Ukrainian Soviet Socialist Republics.
Soviets establish influence over Baltic states
The Soviet Union invaded Finland with some 450,000 men, without declaring war and in violation of three non-aggression pacts. Despite numerical superiority, the Soviets suffered repeated setbacks until reinforcements allowed them to break through in January 1940. At the Moscow Peace Treaty, the Finns agreed to cede significant territory along the border of the two states, including the Karelian Isthmus.