Ideas of using concentration camp prisoners for mobile construction brigades dated to 1941, when the idea was first proposed by the SS-WVHA to develop Nazi-occupied Eastern Europe. The bombing of Lübeck on 28/9 March 1942 marked the beginning of area bombing of German cities, which caused significant destruction. Deployment of forced labor to repair the damage was initiated by local bureaucrats; German historian Karola Fings notes that the demand "points to general acceptance of the concentration camps". In September 1942, Himmler recommended using concentration camp prisoners for the fabrication of window and door frames (in various concentration camps) and producing brick tiles in the Neuengamme brickworks. At the same time, he authorized the formation of SS construction brigades (), detachments of concentration camp prisoners who operated in bomb-damaged cities for clearing debris and repairing damaged buildings. Prisoners in these brigades lived and worked in plain sight of the German population.