Among those killed were Maciej Rataj , Stefan Bryła , Tadeusz Tański , Mieczysław Niedziałkowski , Janusz Kusociński and Stefan Kopec . Actions were started on a similar scale in other Polish areas annexed by Nazi Germany . According to many historians , including Norman Davies , the action against Polish leaders was coordinated with the authorities of the Soviet Union , who at the same time perpetrated the mass murder of 22,000 Polish military officers at Katyń and other places
mass murder of 22,000 Polish military officers
Katyn massacre
German AB-Aktion in Poland