The history of Poland from 1939 to 1945 encompasses primarily the period from the invasion of Poland by Nazi Germany and the Soviet Union to the end of World War II. Following the German–Soviet non-aggression pact, Poland was invaded by Nazi Germany on 1 September 1939 and by the Soviet Union on 17 September. The campaigns ended in early October with Germany and the Soviet Union dividing and annexing the whole of Poland. After the Axis attack on the Soviet Union in the summer of 1941, the entirety of Poland was occupied by Germany, which proceeded to advance its racial and genocidal policies across Poland. Under the two occupations, Polish citizens suffered enormous human and material losses. According to the Institute of National Remembrance estimates, about 5.6 million Polish citizens di