September 1, 1939
September Campaign
The September Campaign began on September 1, 1939, with Germany's attack on Poland, and on September 17, the Soviet Union joined the invasion. Despite heroic defense, including the symbolic defense of Westerplatte, the military superiority of the aggressors led to Poland's defeat. The campaign ended on October 6, 1939, with the capitulation of the last regular units at Kock.