RAF raids on Cologne and Hamburg

Lists of air raids record an RAF raid on Cologne under 5 April 1942 and a heavy bombing of Hamburg under 8 April. Both entries refer to night operations by the British bomber force, RAF Bomber Command, which took off on the evening of the day given and attacked their targets after midnight: Cologne on the night of 5–6 April and Hamburg on the night of 8–9 April. Each set a new record for the number of aircraft dispatched to a single target. Yet neither achieved a success to match the raid on Lübeck at the end of March. Both attacks show clearly where the limits of the British bombing offensive lay in the spring of 1942: the command could now send several hundred aircraft over Germany, but it still could not make their bombs fall in one place.

Harris and his forces

From 22 February 1942 Bomber Command was led by Air Marshal Arthur Harris. He took over just as the Air Ministry issued a new directive: the main objective of the raids was to be the morale of the civilian population, and in particular of the industrial workers, and the aiming points were to be the built-up areas of towns. Harris had fewer than four hundred serviceable aircraft with trained crews at his disposal. Most of them were twin-engined Vickers Wellington and Handley Page Hampden bombers. The heavy four-engined Stirlings, Halifaxes and Lancasters were only slowly reaching the squadrons, and the twin-engined Avro Manchester, with its unreliable engines, was already being withdrawn. Harris wanted to prove to the government, which was considering transferring some of his aircraft to the war against the U-boats and to the Middle East, that his command could inflict serious losses on Germany. He needed big raids, and he needed them quickly.

His main hope was the Gee radio navigation system. A receiver in the aircraft measured the difference in the arrival times of pulses from three transmitters in England, and from this the navigator worked out his position. The first raids using it in March produced mixed results. Gee made it possible to lead hundreds of aircraft along a common route into the vicinity of the target, but its accuracy over the Ruhr was several kilometres – not enough to hit a town shrouded in industrial haze. The system’s range ended in western Germany: Cologne lay comfortably within it, Hamburg at its edge or beyond. Still only some of the aircraft carried receivers. Under the tactics adopted, these flew in the first wave and dropped flares and incendiaries, and the rest bombed the fires they had started. Everything therefore depended on whether the first crews found the target, and on the weather.

Cologne, the night of 5–6 April

Cologne was a well-known target for Bomber Command. On the night of 13–14 March 1942, 135 aircraft had attacked it using the new tactics, and this was regarded as the first fully successful raid conducted with the help of Gee. Three weeks later Harris sent almost twice that force against the same city. On the night of 5–6 April, Easter Sunday, 263 aircraft set out for Cologne – more than in the raid on Essen of 25–26 March, in which 254 bombers had taken part. It was Bomber Command’s largest operation against a single target since the start of the war.

The result was disappointing. The crews reported a successful attack, but according to post-war studies based on Bomber Command’s operational records the bombing was scattered and the damage to the city slight. The first wave failed to mark the target accurately, and when the fires started by incendiaries are spread over a wide area, the following waves, instead of concentrating, scatter even further. That same night twenty other bombers attacked the Gnome et Rhône aero-engine factory at Gennevilliers near Paris, without hitting it, while smaller groups flew to the port of Le Havre and laid mines off the French coast. Of all 318 sorties flown that night, five aircraft failed to return.

The next night, 6–7 April, Harris sent 157 aircraft against the Krupp works in Essen. Storms, icing and cloud broke up this attack too. Only light damage was recorded in the city, and five aircraft failed to return.

Hamburg, the night of 8–9 April

Hamburg, the Reich’s largest port, home to great shipyards building submarines and an industrial centre, had been bombed since 1940. In 1940–1942 it suffered more than a hundred smaller raids, none of which did damage comparable to what came later. According to German studies, as early as September 1941 the Gauleiter of Hamburg, Karl Kaufmann, citing the destruction caused by the raids, pressed Hitler for the deportation of Hamburg’s Jews so that their flats could be given to those who had been bombed out; deportations from Hamburg began in October that year. The city, however, lay far from the English airfields, on the broad Elbe, with strong anti-aircraft defences, and for crews navigating at night it was a difficult target.

On the night of 8–9 April 1942, 272 aircraft took off for Hamburg: according to the operational records, 177 Wellingtons, 41 Hampdens, 22 Stirlings, 13 Manchesters, 12 Halifaxes and 7 Lancasters. This was a new record, nine aircraft more than the Cologne raid three nights earlier. This time the obstacle was the weather. Over the North Sea and over Germany the bombers flew into storms and zones of severe icing. Crews later recalled St Elmo’s fire, glowing rings around the propellers and little blue flames along the edges of the wings; aircraft weighed down by ice lost height, and some crews turned back or dropped their bombs wherever they could. Cloud lay over Hamburg.

According to the operational diary, the damage in Hamburg was slight. The bombs were scattered over a large part of northern Germany. Some fell on Bremen, where, according to a Canadian chronicle of the air war based on Bomber Command’s records, they hit a shipyard and damaged several submarines under construction there. Four Wellingtons failed to return, as did a Manchester of No. 83 Squadron, whose crew were killed apart from one airman who was taken prisoner.

A month of disappointments

The raids on Cologne and Hamburg were not exceptions. Over the following nights of April Bomber Command attacked the same targets again and again, mostly with the same result. On the night of 10–11 April, 254 aircraft set out for Essen; over the target they found cloud instead of the clear skies that had been forecast. That night a Halifax of No. 76 Squadron dropped an 8,000-pound (about 3,600-kilogram) high-explosive bomb for the first time, to no visible effect. Two nights later, on 12–13 April, 251 bombers set out for Essen and at last started a fire in the Krupp works. According to the operational diary, in the course of the month Bomber Command sent eight large raids against Essen, 1,555 sorties in all, lost 64 aircraft, and hit the Krupp factory only twice. The diary summed up the problem aptly: the command now had enough aircraft to take on targets of this size and was able to find them, but it could not mark them accurately and hit them. On the nights of 14–15 and 15–16 April the bombers went to Dortmund and were again scattered in haze and cloud, and on 17–18 April more than 170 aircraft returned to Hamburg.

Such was the picture of the British offensive in the first weeks of Harris’s command. The growing number of aircraft did not translate into effectiveness, and losses, though still moderate, were high in relation to the results. Gee was not enough for aiming, the night sky over Europe was often covered by cloud, and the first waves had neither special equipment nor target-marking bombs that would clearly show the target to those following. The success at Lübeck had come about because the town lay on the coast, was weakly defended and was attacked on a clear, moonlit night. Cologne and Hamburg showed that such conditions were rare.

Place in the war

The April raids on Cologne and Hamburg are among the less well-known episodes of the British bombing offensive, but they were a stage in building up its scale. Harris was accustoming his command to sending ever larger forces against a single target, and a few weeks later this allowed him to gather, with the help of the training units, more than a thousand bombers for the raid on Cologne on the night of 30–31 May 1942. The original target of that operation had in fact been Hamburg; the choice of Cologne was decided by the weather.

At the same time Bomber Command was looking for other approaches. On 17 April 1942 twelve new Lancasters of Nos. 44 and 97 Squadrons flew by day, at very low level, against the MAN works in Augsburg, which built about half the diesel engines for German submarines. Because of an error in the timing of the diversionary operations, No. 44 Squadron’s formation ran into German fighters returning to their airfield over France, which shot down four Lancasters. Over Augsburg anti-aircraft fire brought down three more. Of the twelve aircraft, five returned. Seventeen bombs fell on the factory’s tool shop, five of which failed to explode; the building was badly damaged, but most of the machinery survived and production continued. The leader of the raid, Squadron Leader John Nettleton of No. 44 Squadron, who was born in South Africa, was awarded the Victoria Cross, and Winston Churchill called the attack an outstanding achievement of the RAF. The command’s conclusions, however, were sober: daylight raids on defended targets deep in Germany had proved just as costly as in 1940.

The April failures also showed the need for a specialised force that would find and mark targets for the main force. Harris long opposed it, but in August 1942 the Pathfinder Force was formed, and at the turn of 1942 and 1943 the more accurate Oboe and H2S radar came into service. Only these made possible the destruction of the great cities of the Ruhr and the Rhineland, Cologne among them. Hamburg met that fate in the summer of 1943, when during Operation Gomorrah a firestorm killed some 34,000 people in the city.