The theory of strategic heavy bombing was developed at the end of the First World War. By the 1930s leaders of the the Luftwaffe and the Royal Air Force believed that mass long-range bombing raids had the potential to force the enemy to surrender.
However, at the beginning of the Second World War all air forces had a policy of attacking military targets only. This changed in September 1940, when the Luftwaffe began large-scale night raids on London, Liverpool, Birmingham, Plymouth, Bristol, Glasgow, Southampton, Coventry, Hull, Portsmouth, Manchester, Belfast, Sheffield, Newcastle, Nottingham and Cardiff. Night-time raids dramatically reduced accuracy and it became impossible for pilots to concentrate on bombing military targets.
The Royal Air Force responded by carrying out night-raids on Germany. Poorly trained for this kind of work, pilots lacked the navigational aids for this task. By the end of 1941 the RAF had dropped 45,000 tons of bombs on Germany but these attacks failed to bring the end of the war closer.
Charles Portal of the British Air Staff argued for a change of policy. He advocated that entire cities and towns should be bombed. Portal claimed that this would quickly bring about the collapse of civilian morale in Germany. When Air Marshall Arthur Harris became head of RAF Bomber Command in February 1942, he introduced a policy of area bombing (known in Germany as terror bombing) where entire cities and towns were targeted.
Using incendiary bombs to illuminate targets, the RAF concentrated on the heavy industrial areas of the Ruhr. Harris also ordered massive attacks on the small coastal cities of Lubeck and Rostock. Although a great deal of damage was done these raids had little impact on the German economy or civilian morale.
Massive air attacks on Germany continued and in May 1942 Arthur Harris ordered a 1,050 bomber raid on Cologne. This involved the Royal Air Force using every aircraft available and in two hours over a third of the city was badly damaged.
The introduction of the Avro Lancaster in the second-half of 1942 improved the effectiveness of strategic bombing. This new plane had oboe, an improved navigational device based on radar, and this increased bombing accuracy. The use of pathfinders and the employment of the Mosquito as a high-altitude photo-reconnaissance aircraft also helped improve the success of these raids.
Arthur Harris demanded that Winston Churchill provided more resources for Bomber Command. Along with Charles Portal he argued that if he had 6,000 bombers at his disposal he would force the German government to surrender and there would be no need for an Allied invasion of Europe.
In 1942 scientists in Britain developed an idea that they believed would confuse Germany's radar system. Given the codename of Window the strategy involved the Pathfinder Force dropping strips of metallised paper over the intended target. By early 1943 a series of tests had shown Bomber Command that Window would be highly successful. However, the British government feared that once the secret was out, the Germans would use it to jam Britain's radar system. It was not until July 1943 that permission was finally given to use Window during the bombing of Hamburg.
Window was a great success and was employed by the RAF for the rest of the war. The Germans were forced to change its strategy in dealing with bombing raids. As Air Marshall Arthur Harris later pointed out: "The Observer Corps now plotted the main bomber stream and orders were broadcast to large numbers of fighters with a running commentary giving the height, direction and whereabouts of the bomber stream, and of the probable target for which it was making or the actual target which it was attacking."
Throughout 1943 the Royal Air Force bombed German cities at night while the United States Army Air Force (USAAF) under Carl Spaatz used its B-17 planes for its precision daylight operations. In August 1943 repeated incendiary attacks on Hamburg caused a firestorm and 50,000 German civilians were killed. By the end of 1943 the Allied air forces had dropped a total of 200,000 tons of bombs on Germany.
In early 1944 the USAAF introduced the long-range Mustang P-51B fighter. This new aircraft could escort bombers all the way to targets deep inside Germany. It was an outstanding combat plane and inflicted considerable damage on the Luftwaffe.
Despite objections from Arthur Harris and Carl Spaatz, the bombing campaign changed during the summer of 1944. As part of Operation Overlord, the task of the RAF and the USAAF was to destroy German communications and supply lines in Europe. The destruction of German oil production was also made a priority target and by September, 1944, the Luftwaffe's fuel supply had been reduced to 10,000 tons of octane out of a monthly requirement of 160,000 tons.
By the end of 1944 the Allies had obtained complete air supremacy over Germany and could destroy targets at will. On 3rd February, 1,000 bombers of the United States Army Air Force killed an estimated 25,000 people in Berlin.
Arthur Harris now devised Operation Thunderclap, an air raid that would finally break the morale of the German people. To enable maximum impact to take place Harris chose Dresden as his target. This medieval city had not been attacked during the war and was virtually undefended by anti-aircraft guns. On 13th February 1945, 773 Avro Lancaster bombers attacked Dresden. During the next two days the USAAF sent 527 heavy bombers to follow up the RAF attack. The resulting firestorm killed around 135,000 people.
The United States Army Air Force strategic bombing campaign against Japan was also stepped up. The large number of Japanese buildings made of wood made it easy for the bombers to create firestorms. On the 9th and 10th March 1945, a raid on Tokyo devastated the city. This was followed by attacks on other Japanese cities.
By the summer of 1945 the USAAF was ready to mount its final strategic bombing campaign. On 6th August 1945, a B29 bomber dropped an atom bomb on Hiroshima. Japan continued to fight and a second bomb was dropped on Nagasaki three days later. On 10th August the Japanese surrendered. The Second World War was over.