The Allied bombing of Hamburg during World War II included numerous attacks on civilians and civic infrastructure. As a large city and industrial centre, Hamburg's shipyards, U-boat pens, and the Hamburg-Harburg area oil refineries were attacked throughout the war.
As part of a sustained campaign of strategic bombing during World War II, the attack during the last week of July 1943, code named Operation Gomorrah, created one of the largest firestorms raised by the Royal Air Force and United States Army Air Forces in World War II, killing an estimated 34,000 people in Hamburg, wounding 180,000 more, and destroying 60% of the city's houses.
Hamburg was selected as a target because it was considered particularly susceptible to attack with incendiaries, which, from the experience of the Blitz, were known to inflict more damage than just high explosive bombs. Hamburg also contained a high number of targets supporting the German war effort and was relatively easy for navigators to find. Extensive research was done on behalf of both the RAF and USAAF to discover the optimum mix of high explosives and incendiaries. Before the development of the firestorm in Hamburg, there had been no rain for some time and everything was very dry. The unusually warm weather and good conditions ensured that the bombing was highly concentrated around the intended targets, and helped the resulting conflagration create a vortex and whirling updraft of super-heated air which became a tornado of fire.
Various other previously used techniques and devices were instrumental as well, such as area bombing, Pathfinders, and H2S radar, which came together to work with particular effectiveness. An early form of chaff, code named "Window", was successfully used for the first time by the RAFclouds of aluminium foil strips dropped by Pathfinders as well as the initial bomber streamin order to completely cloud German radar.
The July 1943 raids inflicted severe damage to German armaments production in Hamburg. The overall effect on Germany's second-largest city was a great shock to the Nazi leadership. As a result, the air defences on the German home front were substantially increased, with both anti-aircraft guns and fighter aircraft being diverted from the front line areas. This shift to home defence remained a significant drain on Germany's effort on the fighting fronts for the remainder of the war.
Background
Political and military pressure RAF Bomber Command had made raids on Germany from the early days of World War II. Initially, only military targets were attacked. Navigation to the target over a blacked-out wartime landscape was extremely poor, as was bombing accuracy - even if the target city (let alone the actual military target) could be found. Consequently bombing operations were very open to criticism as a waste of resources, since such poor results were achieved. The extent of this failure was exposed to the War Cabinet in August 1941 by the Butt Report, which by analysing 600 photographs of raids in the previous three months, found that only a third of crews that claimed to have reached their targets had actually dropped their bombs within of them.
Opinion on targeting steadily shifted as the war progressed, and by November 1940, the view was developing that the civilian population of Germany was a legitimate target in "total war". By June 1941, RAF thinking had been reversed from seeing any civilian casualties as collateral damage when attacking a military target, to deliberately targeting civilians in an attempt to destroy their morale. This was expected to reduce industrial production and therefore hinder the German war effort. The target was no longer factories, but the people who worked in them and their homes in the surrounding area. This became known as "area bombing". This change was driven not by the inaccuracy of bombing at this stage, but by studying which aspects of the German Blitz on Britain had had most effect. Factories had been seen to be relatively difficult to destroy, but workers needed somewhere to live, and their housing was much more easily made unusable. The absenteeism of de-housed workers was considered to have a bigger effect on industrial production than the level of damage that could be caused, with the same effort, to the factories in which they worked.
Air Marshal Arthur "Bomber" Harris had taken charge of the RAF Bomber Command in February 1942. In the same month, the USAAF 8th Bomber Command set up a headquarters in the United Kingdom ready for the deployment of American units to Britain. Roosevelt was optimistic that bombing had war-winning potential, despite his appeal to Hitler in September 1939 to avoid bombing civilians. Winston Churchill was similarly enthusiastic to bomb Germany. This gave both air forces the political support to deal, at this stage, with criticism of their ineffectiveness.
The build-up of the 8th Bomber Command was slow and though it made some small-scale raids in France during the latter half of 1942, US capability to bomb Germany was not obtained until 1943. The British resources were also limited by competing demands for aircraft. The Western Allies had had to tell the Soviet Union that any idea of opening a second front in Europe in the summer of 1942 was unfeasible. The only thing Churchill had to offer Stalin was a bombing campaign against Germany. This was hard for the RAF to deliver, but it meant that the bombing of Germany could not be abandoned, so Harris would ultimately get the heavy bombers needed. By the time of the big raid on Hamburg at the end of July 1943, both air forces needed a significant success to justify their existence.
Firebombing research Britain's experience of being bombed in the Blitz had contributed to the RAF's thinking on how to conduct a bombing campaign. It had become clear that incendiaries could inflict much more damage than high-explosive bombs. Detailed study of this was carried out by the Research and Experiment unit, RE8, (set up in November 1941). The details of how German houses were constructed were examined, and tests were carried out on models to determine how effective an incendiary attack would be. The optimum ratio of high-explosive bombs and incendiaries was calculated. The high explosive was to blow out windows and make firefighting dangerous. High-explosive bombs with delayed-action fuses were included in the mix to further suppress any firefighting effort. The quantity of incendiaries delivered had to be high enough to totally overwhelm any firefighting capability, so that a conflagration could become established.
The Americans took a high level of interest in the British research on the effect of incendiaries. American expertise and experiments by the Standard Oil Development Company and the U.S. Army's Chemical Warfare Service Technical Division added to the planning of fire bombing raids. Despite belief to the contrary, US aircraft also carried a carefully considered mix of high explosive and incendiary bombs. Large quantities of US-made oil-based incendiaries went into service with the 8th Bomber Command shortly before the Hamburg raid – this was preferred by the Americans to the magnesium-cased thermite bomb used by the British.
The effectiveness of the Hamburg raid relied to a large extent on extensive research into how best to cause a large fire in a German city – as opposed to the popular view that it was an accidental occurrence due to unusual weather conditions.
Target selection A number of factors led to Hamburg being chosen for the planned firebombing raid. The construction of the city meant its vulnerability was considered "outstanding". It was Germany's second-largest city. The city's shipbuilding industry made it a priority target. It also had more industrial targets of interest to the Ministry of Economic Warfare than most other German cities. It was reasonably close to the bomber bases in Britain, so giving a short flight with less exposure to anti-aircraft fire and fighters. Hamburg's position close to the coast and on a prominent river made the target easy to find.
Operation Gomorrah
Operation Gomorrah, was a campaign of air raids which began on 24 July 1943 and lasted for eight days and seven nights. It was at the time the heaviest assault in the history of aerial warfare. The name Gomorrah comes from that of one of the two Canaanite cities of Sodom and Gomorrah whose destruction is recorded in the Bible.
Before July 1943, RAF Bomber Command's focus had been on the Ruhr industrial region which had been the target of a five-month-long campaign.
Operation Gomorrah was carried out by RAF Bomber Command (including RCAF, RAAF and Polish Squadrons) and the USAAF Eighth Air Force. The British conducted night raids and the USAAF daylight raids.
The initial attack on Hamburg included two new introductions to the British planning: they used "Window", later known as chaff, to confuse the German radar, while the Pathfinder Force aircraft, which normally kept radio silence, reported the winds they encountered, and this information was processed and relayed to the bomber force navigators.
First RAF raid 24/25 July The first raid on Hamburg was planned for the night of 23 July, but the raid was delayed by one day because of bad weather. Between 21:45 and 23:00 on 24 July 791 bombers took off from their airfields. At 00:57 Pathfinder aircraft, guided only by H2S radar, started to drop yellow target indicators and flares. This was followed by others dropping red target indicators visually by the light of the flares. No. 35 Squadron led the target marking and, thanks to the clear weather and H2S radar, accuracy was good, with markers falling close to the aiming point scattered over five districts. At 01:02 the main force started to bomb; this continued until 01:50 in six waves. Less than half of the bombers dropped their bombs within a radius of the aiming point. Around Hamburg the Germans had lit red decoy fires which caused a hundred bombers to bomb those in error. Still, large areas were set on fire in the five districts marked by the Pathfinders. During the raid a large () creepback developed which saved the city centre from catastrophe but caused other districts to the north to be set on fire as well. While some 40,000 firemen were available to tackle fires, control of their resources was damaged when the telephone exchange caught fire and rubble blocked the passage of fire engines through the city streets; fires were still burning three days later. During the early stages of the raid, some bombs fell on the Blohm and Voss shipyard, where three U-boats were destroyed: U-1011 and U-1012 were hit on their slipways and never repaired, and U-996 sank at the dockside. The local police estimated the number of deaths at 1500.
First USAAF raid 25 July A second daylight raid by the USAAF was conducted on 25 July. 323 aircraft attacked Hamburg, Kiel and Warnemünde. 127 aircraft were assigned to bomb the Blohm and Voss shipyard and the Klöckner aero-engine factory in Hamburg. On the outward leg of the raid, the formation was attacked by about 30 German fighters. Only two bombers were lost before reaching the target. 90 out of 127 Boeing B-17 Flying Fortresses reached Hamburg at 16:40. Despite being partly covered in smoke from the previous night bombing, some buildings in the shipyard were hit but the vital U-boat construction slipways were not damaged. The aero-engine factory was completely covered by smoke and secondary targets were bombed instead, including a generating station. Two large liners used as a depot and barracks ship were hit and sunk. German flak damaged 78 aircraft; ten of the damaged bombers that had to leave the formation were finished off by fighters. Over the North Sea on the way back to bases, the formation was attacked by eight night-fighters operating from The Netherlands but they achieved nothing, whilst losing one of their number.