During the Second World War, the holdings of the Düren municipal archive were moved out of storage. A large part was located at Nideggen Castle in the Eifel, about 13 kilometres south of Düren. The area was heavily fought over by Germans and Americans from November 1944 to February 1945 (Battle of the Huertgen Forest). The castle was destroyed by bombing or the effects of war and could no longer be found after 1945; between 22 November 1944 and 31 July 1945, numerous documents from the 9th to 18th centuries were stolen from the castle.
