Operation Tannenberg (German: Unternehmen Tannenberg) was the codename for one of the extermination actions directed at the Polish people during World War II, part of the Generalplan Ost. Proscription lists (Sonderfahndungsbuch Polen), prepared by Germans before the war, identified more than 61,000 members of the Polish elite: activists, intelligentsia, scholars, actors, former officers, and others, who were to be interned or shot. Members of the German minority living in Poland assisted in preparing the lists.
First, in August 1939 about 2,000 activists of Polish minority organisations in Germany were arrested and murdered. The second part of the action began on September 1, 1939, and ended in October, resulting in at least 20,000 deaths in 760 mass executions by Einsatzgruppen special task units with some help from regular Wehrmacht (armed forces) units. In addition, a special formation was created from the German minority living in Poland called Selbstschutz, whose members had trained in Germany before the war in diversion and guerilla fighting (see: Deutscher Volksverband, the German People's Union in Poland). The formation was responsible for many massacres and due to its bad reputation was dissolved by Nazi authorities after the September Campaign.
Verbatim transcript of Part I of the book The German New Order in Poland published for the Polish Ministry of Information by Hutchinson & Co., London, in late 1941. The period covered by the book is September, 1939 to June, 1941
Andrzej Leszek Szcześniak (2001). Plan zagłady Słowian - Generalplan OST. Radom, POLWEN. ISBN83-88822-03-9.
Alfred Spiess, Heiner Lichtenstein: Unternehmen Tannenberg. Der Anlass zum Zweiten Weltkrieg. Korrigierte und erweiterte Ausgabe. (Ullstein-Buch ; Nr. 33118 : Zeitgeschichte) Ullstein, Frankfurt/M ; Berlin 1989, ISBN 3-548-33118-1.