Blast furnaces of the Kloeckner works in Haspe, one of the largest producer of iron and steel in the Ruhr, photographed before 1939.
In World War II, the Rhine-Ruhr area was one of the primary targets for air raids [-> Chronicle of the air raids]. This industrial region was regarded as the "Armory of the Third Reich". In numerous plants of Krupp, Vereinigte Stahlwerke AG, Kloeckner, Rheinmetall, Hoesch and Ruhrstahl produced the arms, which enabled Hitler to wage war.
The rolling mills and steel works manufactured the components of tanks, aircrafts, submarines, cannons and many other weapons. The city of Essen and the Krupp works were synonyms for 'weapons from the Ruhr'.
A large number of hard coal bills and coking plants supplied the vital raw material for the wartime economy, chemical industries, railway traffic, and power supply. Several synthetic oil plants produced aviation petrol, fuel oil, and motor car fuel. The IG Farben plant in Hüls (near Marl) was one of the most important manufacturers of synthetic rubber (Buna) in Germany.
Since 1850 the entire Ruhr district was an important railway junction. Numerous marshalling yards completed the railway traffic and were 'coal gates', in order to transport the hard coal into other regions of Germany. The large railway station in Hamm was the turntable for the goods traffic from West and East Germany towards the Rhine and France. The railway traffic between North and South Germany ran particularly over the stations in Hagen.
Already before outbreak of World War II the Ruhr district was one of the largest population centers in Europe In 1939 more than 4 million humans lived at Rhine and Ruhr. Because of the numerous municipalities the Ruhr district can be compared with a only one enormous city The actual Ruhr district extends between the Rhine with Duisburg in the west into the Hamm-Hellweg area in the east. In the north the region is limited by the Lippe river and in the south by the Ruhr and the industrial district around Hagen.
In addition, for the Allied air forces in World War II the Rhineland and those areas bordering the Ruhr area in north, east, and south (Sauerland, Siegerland, Münsterland, Ostwestfalen) were also parts of the 'Ruhr'. Cities such as Aachen, Krefeld, Münster, Bielefeld, Cologne, Duesseldorf, Siegen, Bonn, and Wuppertal were bombed in connection with the Allied Air offensive against the Ruhr district.
First air raids
Priority targets of the Bomber Command in the Ruhr area 1940
Since the middle of the 19th century the industrial Rhine-Ruhr region played an important role in the manufactoring of arms and War armament. That is why already in World War I Britain and French planned air attacks on individual industrial cities there, like Essen, Duisburg, Oberhausen and Hagen. Since 1937 power stations and coking plants in the Rhine-Ruhr-area topped the list of targets for attacks of British plans for the strategic air war against Germany.
In April 1940 the Air Ministry published a new directive. Now marshalling yards and synthetic oil plants in the Ruhr area were the principal targets. In May 1940 the Bomber Command opened with this directive the strategic air war against Germany. Night for night British airplanes started against the Ruhr district. For example, from May to December 1940 the marshalling yards in Hamm was target for Bomber Command in over 100 nights. But the damage developed there was insignificant.
Inhabitants of Hagen with the part of a crashed Hampden aircraft of Bomber Command, shot down by flak on its way to Merseburg, August 16/17, 1940.
During the first two years of the war, the numerous railroad installations and synthetic oil plants in particular were important targets for attacks by the British Bomber Command. In the fall of 1941 the opinion gained acceptance in the British target-planning committees that the precision attacks on individual industrial plants since May 1940 had had no results.
Following the German air attacks on British cities in the fall of 1940 and the spring of 1941, which in London alone had caused c. 40,000 deaths, the British Air Ministry and the War Cabinet developped plans for area attacks on important German industrial cities such as Cologne, Dusseldorf, Duisburg, Essen and Hamburg. In the autumn 1941 the Unison plan was discussed. It planned air raids on the populated areas in different industrial cities.
Large-caliber 4000 lb "Blockbuster" bombs should open the inflammable materials by their air pressure. By dropping incendiary bombs on a massive scale, the residential and business quarters in the cities were to destroyed as well as the morale of the civil population to be hit.
Area attacks on Ruhr cities
British leatfleat about the "1000-bomber-raid" against Cologne, June 1942
On February 14, 1942 a corresponding directive determined the conduct of the air war by the British Bomber Command from then on until the end of the war. Area attacks should destroy the moral of the German population and the infrastructure in the large cities.
By the "1000-bomber-raid" on Cologne in the night of May 29/30, 1942, major damage and a great number of casualties (c. 460 people) were for the first time caused in one of the largest cities in Germany. But the numerous area raids on the main Ruhr city Essen in the spring and in the summer 1942 were less successful. The strong air defense and not existing target-finding devices made attacks on Essen, Bochum, Hagen, Gelsenkirchen, Dortmund and other Ruhr towns very difficult. But the cities lying beside the well locatable Rhine river, particulary Duisburg, Duesseldorf and Cologne, suffered frequently heavy damage and high person losses.
Running parallel to their air raids, the Allies conducted an exensive psychological warfare. Until the end of the war in May 1945 their strategic and tactical air forces dropped billions of leafleats over Germany. In this way and by allied broadcastings the German population was to be informed of the crimes of there government and of the actual military situation.
Avro Lancaster Mk I, 1943 (Imperial War Museum, London)
But it was not until the development of radar and modern target-finding devices as well as the creation of an effective air force consisting mainly of the four-engined bombers Avro Lancaster, Handley Page Halifax, and Short Stirling that the start of an extensive bombing offensive against the German Reich became possible. In addition, since May 1942 first units of the American 8th USAAF were stationed in Britain.
At the conference of Churchill and Roosevelt held in Casablanca in January 1943, a combined bombing offensive by the British and U.S. air forces had been agreed upon. The Americans were to attack important industrial plants and railway junctions in Germany mainly during the day, the British were to carry out their area raids mainly at night.