Sonderaktion Tannenberg

Operation Tannenberg Unternehmen Tannenberg
Operation Tannenberg, 20 October 1939, the mass murder of Polish townsmen in western Poland
Location	German occupied Poland
Date	1939
Target	Polish people
Attack type	Genocidal massacre, mass shooting
Weapons	Automatic weapons
Deaths	20,000 deaths in 760 mass executions by SS Einsatzgruppen
Perpetrators	Nazi Germany

Operation Tannenberg (German: Unternehmen Tannenberg) was a codename for one of the extermination actions by Nazi Germany that was directed at the Polish nationals during the opening stages of World War II in Europe, part of the Generalplan Ost for the German colonization of the East. The shootings were conducted with the use of a proscription list (Sonderfahndungsbuch Polen), compiled by the Gestapo in the span of two years before the 1939 attack.

The top secret lists identified more than 61,000 members of the Polish elite: activists, intelligentsia, scholars, clergy, 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.It is estimated that up to 20,000 Germans living in Poland belonged to organizations involved in various forms of subversion.

Operation Tannenberg was closely followed by the Intelligenzaktion, a second phase of the Unternehmen Tannenberg directed by Heydrich's Sonderreferat from Berlin. It lasted until January 1940. In Pomerania alone, 36,000–42,000 Poles, including children, were killed before the end of 1939.

The plan was finalized in May 1939 by the Central Office II P (Poland). Following the orders of Adolf Hitler, a special unit dubbed Tannenberg was created within the Reich Main Security Office (Reichssicherheitshauptamt). It commanded a number of Einsatzgruppen units formed with Gestapo, Kripo and Sicherheitsdienst (SD) officers and men who were theoretically to follow the Wehrmacht (armed forces) into occupied territories. Their task was to track down and arrest all the people listed on the proscription lists exactly as it has been compiled before the outbreak of war.