 In October 1937, Belgium signed a non-aggression pact with Germany.During World War II, the bombing of the Ruhr in 1940–1944 caused a loss of 30% of plant and equipment (compared to 15–20% for German industry as a whole).A second battle of the Ruhr (6/7 October 1944 – end of 1944) began with an attack on Dortmund.