High Quality Content by WIKIPEDIA articles! The occupation of Poland by Nazi Germany and the Soviet Union during the Second World War (1939-1945) began with invasion of Poland in September 1939, and formally concluded with the defeat of Nazism by the Four Powers in May 1945. Throughout the entire course of foreign occupation the territory of Poland was divided between Nazi Germany and the Soviet Union (USSR). In summer-autumn of 1941 the lands annexed by the Soviets were overrun by Nazi Germany in the course of the initially successful German attack on the USSR. After a few years of fighting, the Red Army was able to repel the invaders and drive the Nazi forces out of the USSR and across Poland from the rest of Eastern and Central Europe.