From the first day of invasion, the German air force (the Luftwaffe) attacked civilian targets and columns of refugees along the roads to terrorize the Polish people, disrupt communications and target Polish morale. The Luftwaffe killed 6,000 to 7,000 Polish civilians during the bombing of Warsaw.

The German invasion saw atrocities committed against Polish men, women and children. The German forces (both SS and the regular Wehrmacht) murdered tens of thousands of Polish civilians (such as the Leibstandarte SS Adolf Hitler was notorious throughout the campaign for burning villages and committing atrocities in numerous Polish towns, including massacres in Błonie, Złoczew, Bolesławiec, Torzeniec, Goworowo, Mława and Włocławek).

During Operation Tannenberg, a campaign of ethnic cleansing organized by multiple elements of the German government, tens of thousands of Polish civilians were shot at 760 mass execution sites by the Einsatzgruppen.

Altogether, the civilian losses of Polish population amounted to about 150,000 to 200,000. Roughly 1,250 German civilians were also killed during the invasion. (Also, 2,000 died fighting Polish troops as members of ethnic German militia forces such as the Volksdeutscher Selbstschutz, which was a fifth column during the invasion.)