From 1944, the SS and Nazi Party gained much greater control in Belgium, particularly after the military government was replaced in July by a Nazi civil administration, the Reichskommissariat Belgien-Nordfrankreich. In September 1944, Allied forces arrived in Belgium and quickly moved across the country. That December, the territory was incorporated de jure into the Greater German Reich although its collaborationist leaders were already in exile in Germany and German control in the region was virtually non-existent.