In September 1939 in German occupied Poland, an armed ethnic German militia called "Selbstschutz" (Self-Defence) was created. It organised the mass murder of Polish elites in Operation Tannenberg. At the beginning of 1940, the "Selbstschutz" organization was disbanded, and its members transferred to various units of the SS, Gestapo and the German police. Throughout the invasion of Poland, some ethnic German minority groups assisted Nazi Germany in the war effort: they committed sabotage, diverted regular forces and committed numerous atrocities against civilian population.