Wehrmacht troops entered Łódz on September 8, 1939. About 70,000 Jews of the Jewish population escaped prior to the German occupation, but 162,000 Jews still remained in the city. On November 9, 1939, Lodz and its surroundings were annexed to the Reich and integrated into the newly established province Reichsgau Posen. The annexation process was finalized on November 20, after the new border to the neighboring Generalgouvernement (General Government) had been determined.
On January 29, 1940 the province was officially renamed Reichsgau Wartheland after its main river, the Warthe, The Germans immediately implemented the German Municipal Code, ignoring the evolved territorial and administrative structures even in the districts that never had been German before WWI. Already on October 30, 1939, Reichsführer-SS Heinrich Himmler ordered the expulsion of all Jews and "hostile" anti-German Poles from all annexed territories and entrusted the task of planning and organizing orderly deportations to the Reich Security Main Office (Reichssicherheitshauptamt – RSHA), led by his right-hand man, SS-Gruppenführer Reinhard Heydrich.
Himmler appointed Wilhelm Koppe as Higher SS and Police Leader (Höherer SS- und Polizeiführer – HSSPF) for the new province and instructed him to prepare for the immediate expulsion of Poles and Jews. On November 3, Koppe stipulated that 200,000 Poles and 100,000 Jews were to be deported by the end of February 1940. At the same time, Koppe was given the task of murdering the disabled and mentally ill in the Wartheland as part of a larger program – the euthanasia program, born out of the Nazi conclusion that mentally, terminally ill and crippled patients are "a social ballast" who should be "killed out of mercy" (German: Gnadentod). It targeted both Jews and non-Jews....