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.