German war crimes during the invasion of Poland

Nazi Germany's invasion of Poland in 1939 was characterized by mass murders of civilians and prisoners of war, attacks on undefended civilian targets, rapes, looting, destruction of property, and other severe violations of the international humanitarian law committed by German military, police, and paramilitary formations. The advance of Wehrmacht units into Poland was accompanied by a wave of violence.

Source: Wikipedia — German war crimes during the invasion of Poland (CC BY-SA 4.0)