Allied bombing of German cities killed between 305,000 and 600,000 civilians. One of the most controversial aspects of Bomber Command during World War II was the area bombing of cities. Until 1942 navigational technology did not allow for any more precise targeting than at best a district of a town or city by night bombing. All large German cities contained important industrial districts and so were considered legitimate targets by the Allies. New methods were introduced to create "firestorms". The most destructive raids in terms of casualties were those on Hamburg (45,000 dead) in 1943 and Dresden (25,000–35,000 dead)) in 1945. Each caused a firestorm and left tens of thousands dead. Other large raids on German cities which resulted in high civil casualties were Darmstadt (12,300 dead), Pforzheim (17,600 dead) and Kassel (10,000 dead).