After the invasion of Poland in September 1939 , Hitler ordered that the Polish leadership and intelligentsia should be destroyed . The '' Sonderfahndungsbuch Polen '' ( Special Prosecution Book Poland ) — lists of people to be killed — had been drawn up by the SS as early as May 1939 . The '' Einsatzgruppen '' ( special task forces ) performed these murders with the support of the '' Volksdeutscher Selbstschutz '' ( Germanic Self-Protection Group ) , a paramilitary group consisting of ethnic Germans living in Poland . Members of the SS , the Wehrmacht ( German Armed Forces ) , and the '' Ordnungspolizei '' ( Order Police ; Orpo ) also shot civilians during the Polish campaign . Approximately 65,000 civilians were killed by the end of 1939 . In addition to leaders of Polish society , they killed Jews , prostitutes , Romani people , and the mentally ill
Polish leadership and intelligentsia should be destroyed
Intelligenzaktion
Wannsee Conference