Most occupied places had some Polish administration, often adhoc, created after the evacuation of official personnel. Those would be quickly dissolved by the Germans, and the temporary control over those territories was given to military commanders of the rear (Korück, Kommandant des rückwärtigen Armeegebiets). Civilian officials (landrat)s) were quickly assigned to governance of Polish powiats or groups of thereof; in Western cities and villages, Germans were appointed as mayors and vogts, in the central and eastern ones, Polish ones were accepted.
Hitler issued first directions on the occupation administration on 8 September. On 8 and 13 September 1939, the German military district in the area of Poznań was called "Posen", commanded by general Alfred von Vollard-Bockelberg, and "Westpreußen" (West Prussia), commanded by general Walter Heitz, were established in conquered Greater Poland and Pomerelia, respectively. Based on laws of 21 May 1935 and 1 June 1938, the German military, the Wehrmacht, shared its administrative powers with civilian "chief civil administrators" (Chefs der Zivilverwaltung, CdZ). German dictator Adolf Hitler appointed Arthur Greiser to become the CdZ of the Posen military district, and Danzig's GauleiterAlbert Forster to become the CdZ of the West Prussian military district. On 3 October 1939, the military districts "Lodz" and "Krakau" (centered on Łódź and Kraków, respectively) were set up under command of major generals Gerd von Rundstedt and Wilhelm List, and Hitler appointed Hans Frank and Arthur Seyß-Inquart as civil heads, respectively. Thus the entirety of occupied Poland was divided into four military districts (West Prussia, Posen, Lodz, Krakau). Frank was at the same time appointed "supreme chief administrator" for all occupied territories.
Berenstein Tatiana, Rutkowski Adam: Niemiecka administracja wojskowa na okupowanych ziemiach polskich (1 września — 25 października 1939 r.). in: Najnowsze Dziejke Polski. Materiały i studia z okresu II wojny światowej. Bd. VI. Warszawa 1962. S. 45-57