The campaign began on 1 September 1939 following a German - staged attack in Gleiwitz ( Gliwice ) .
The Polish September Campaign was the conquest of Poland by the armies of Nazi Germany , the Soviet Union and a small contingent of Slovak forces during World War II .
The campaign began on 1 September 1939 following a Nazi Germany - staged attack in Gleiwitz ( Gliwice ) .
The Polish September Campaign was the conquest of Poland by the armies of Nazi Germany , the Soviet Union and a small contingent of Slovak forces during World War II .