Kriegslokomotiven (German: for "war locomotives", singular: Kriegslokomotive) or Kriegsloks were locomotives produced in large numbers during the Second World War under Nazi Germany. Their construction was tailored to the economic circumstances of wartime Germany along with conquered and occupied territories across Europe, taking account of the shortage of materials, the transportation of goods in support of military logistics, ease of maintenance under difficult conditions, resistance to extreme weather, limited life and the need for rapid, cheap, mass production. In order to meet these requirements, economic drawbacks such as relatively high fuel consumption had to be accepted. Forced labour was used in the construction of some of the locomotives; German locomotive building firms employed prisoners from concentration camps and foreign, mostly Polish, workers. Kriegsloks were also used to haul Holocaust trains.
The war locomotives (or Kriegslokomotiven) were kept technically as simple as possible and the use of scarce materials (particularly copper) was dropped. Several German firms used prisoners from concentration camps as forced labour in the production of Kriegslokomotiven.Borsig Lokomotiv Werke (AEG) used forced labour from KL Auschwitz,Schichau-Werke used forced labor from KZ Stutthof, and its subcamps. DWM Posen (Deutsche Waffen- und Munitionsfabriken Posen) took over Polish manufacturer H. Cegielski – Poznań and turned its workforce into forced labour. Oberschlesische Lokfabrik Krenau took over Polish manufacturer Fablok and used forced labour under threat of death. Identical engines were produced in Vienna, Kassel, Berlin, Munich, Stuttgart, Kirchen, Plzeň (Pilsen), and Strasbourg.