Around six million Polish citizens, are estimated to have perished during World War II. Most were civilians killed by the actions of Nazi Germany and the Soviet Union. 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. These three crimes in international law were for the first time, from the end of the war, categorized as violations of fundamental human values and norms. These crimes were committed in occupied Poland on a tremendous scale.