War crimes in occupied Poland during World War II

Around six million Polish citizens are estimated to have perished during World War II. Most were civilians killed by the actions of Nazi Germany, the Soviet Union, the Lithuanian Security Police, as well as the Organization of Ukrainian Nationalists and its offshoots (the Ukrainian Insurgent Army, the Self-defense Kushch Units and the Ukrainian People's Revolutionary Army). At the International Military Tribunal held in Nuremberg, Germany, in 1945–46, three categories of wartime criminality were juridically established: waging a war of aggression; war crimes; and crimes against humanity.

Source: Wikipedia — War crimes in occupied Poland during World War II (CC BY-SA 4.0)