By prior agreement, Hitler let Stalin take the eastern two-thirds of Poland.
Hitler said he was responding to Polish provocation, but Polish troops were reacting to a German troop buildup on their western border.
The German invasion began one week after Stalin and Hitler put aside their animosities temporarily and agreed to the Molotov-Ribbentrop Pact, dividing up Poland between Germany and the Soviet Union.
In his "Soldier's Creed", Willem van Stockum cited the
motivation of a soldier as defending "one Polish urchin"
rather than a dream of a postwar Utopia
Britain and France entered the war after two days on behalf of Poland.
But the German army unleashed its Blitzkrieg, or "lightning war". In six days they had taken Krakow, in ten they were outside Warsaw.
The Soviet invasion commenced 16 days later, on Sept. 17, 1939.
The campaign ended on Oct. 6, 1939 with the total division and annexations of Poland.