In late 1941 and early 1942, night raids on Germany weakened. This was partly due to poor weather conditions, and partly because both sides seemed to be regrouping before new battles. On February 14, 1942, the British War Cabinet decided to initiate intensive bombing raids on Germany, initially limiting them to a six-month period.
A week later, on February 21, Air Marshal Sir Arthur Harris was appointed the new Commander-in-Chief of RAF Bomber Command. These two events signaled fundamental changes in the concept of bomber deployment. Harris proposed that raids on major German cities should not aim to destroy one or more specific targets, but rather execute so-called “area bombing.” The primary objective of such massive raids was, in fact, the destruction of residential areas and, consequently, the undermining of civilian morale, especially among industrial workers.
The Chief of Staff of the RAF, Sir Charles Portal, wrote in February 1942: “Regarding the new bombing directive: I believe that in reality, the aiming points in populated areas should not be docks or aircraft factories… This must be absolutely clear, if it is not yet understood by anyone.” Bomber pilots, in response, expressed fears that their losses would immediately increase. Many believed that the only reason they had not yet been shot down by the Germans was their constant alteration of flight paths.
Harris, however, believed that large groups in tight formation (and he proposed using formations of a thousand or more bombers for raids on German cities) would be able to break through German defenses with minimal losses. Harris began with a series of “experimental raids” designed to confirm the validity of his proposals and to test the effectiveness of the new H2S blind bombing system.
Early Mass Raids
The first such operation took place on the night of March 28-29, 1942, when a raid by 234 British bombers completely destroyed the center of Lübeck, killing 300 civilians. Rostock then shared Lübeck’s fate when, during four raids between April 24 and 29, a total of 520 bombers dropped bombs on the city’s historic center.
These raids had a profound psychological effect on the Germans. German newspapers reported them only two days later, and only in a few lines. The military-political leadership of the Third Reich reacted to these raids not by strengthening air defenses, but by ordering retaliatory destruction of old English cities like Exeter, Bath, Norwich, and Canterbury.
On the night of May 30-31, 1942, British bomber aviation conducted its first raid under the “Thousand Plan.” 1047 aircraft, including 602 Wellingtons, 131 Halifaxes, 88 Stirlings, 79 Hampdens, 73 Lancasters, 46 Manchesters, and 28 Whitleys, headed for Cologne, but only about 900 managed to reach their targets. The raid lasted for an hour and a half; three waves of bombers dropped 1349 225-kg high-explosive and over 460,000 incendiary bombs on the city.
As a result of the bombing in Cologne, many apartment buildings were damaged, 13,000 apartments were completely destroyed, 480 people were killed, and approximately 5,000 more were injured. The British themselves lost 41 bombers, or 3.9% of the total participating in this raid; in addition, another 116 aircraft sustained various damages, and 12 of them were subsequently written off.
German Night Air Defense
The events of that night clearly demonstrated the limitations of controlled night combat. British bombers penetrated German airspace across a segment about 30 km wide, crossing only 8 night fighter zones. As a result, the command of the 12th Air Corps could only oppose them with 25 night fighters, some of which were forced to return due to technical problems or damage from the bombers’ defensive fire. Time was needed for replacement fighters to arrive in the corresponding night combat zones.
Although Luftwaffe night fighter pilots shot down more aircraft on the night of May 30-31 than ever before, they still felt a distinct sense of dissatisfaction. Hundreds of pilots and radio operators had to sit helplessly awaiting a takeoff command that never came. Many wanted to know why defense couldn’t be organized as it was during the day. “Free” night combat then became the main topic of discussion among pilots.
However, neither the technical capabilities nor the control systems at the time allowed night fighter aviation to transition to such tactics. Moreover, Kammhuber feared that a shift to “free” night combat tactics, which required fundamental changes in the technical equipment of night fighters, would generally adversely affect their combat readiness. Therefore, he saw only one path: further refinement of existing night combat tactical methods. Kammhuber decided to extend the illuminated belt to the Swiss border to prevent the British from bypassing it. In front of and behind it, “Dunaja” zones, 200 km deep, were to be created, tasked with breaking up the bomber stream.
While Kammhuber’s staff prepared the necessary documents to implement this idea, the British continued their massive raids. On the night of June 1-2, they attacked Essen, which was the second “thousand-bomber” raid, although it involved “only” 956 bombers. Unlike the successful first raid on Cologne, this raid proved unsuccessful for the British, and they failed to achieve their main objective.
Essen was completely enveloped in a dense fog, exacerbated by emissions from numerous industrial chimneys. As a result, most of the bombs fell not on Essen itself, but on smaller surrounding towns, causing numerous casualties there, while in Essen itself only 11 houses were destroyed and “only” 50 people died. That night, the British lost 31 bombers (3.2%). The third “Harris’s Thousand Bombers” raid occurred on the night of June 25-26, when 1067 aircraft dropped bombs on Bremen. This time, British losses amounted to 55 bombers, or 4.9% of their total number.
During these last two raids, night fighters shot down 52 bombers, although their stream crossed significantly fewer night combat zones than in previous raids. The staff of the 12th Corps attributed this success to the effectiveness of the “Dunaja” zones and the fact that many fighters were already equipped with onboard radars. Although this was generally a correct conclusion, it paradoxically proved to be a disservice. On July 31, the anti-aircraft searchlight divisions in the illuminated belt were disbanded, and their searchlights and anti-aircraft batteries began to be redeployed to the “Konaja” zones around major cities.
The Himmelbett System
After the searchlights were withdrawn from the former illuminated belt, Kammhuber kept all radars in their previous positions, despite their range allowing them to be spaced much further apart. Now, one “Würzburg-Gigant” radar, conditionally named “Red Giant” (“Rote Riese”), detected and tracked the enemy, while another, called “Green Giant” (“Game Riese”), tracked friendly fighters.
Data from the radars was transmitted to a command post, where the positions of the target and the fighter were automatically marked on a map of the so-called “Seeburg table-tablet” with red and green dots, respectively. From there, a control officer guided the fighter to the target. This method of operation was named “Himmelbett” (“canopy bed” or “sky bed”).
This tactic had three main disadvantages. Firstly, only one night fighter could be in each “Himmelbett” zone. Of course, since “Himmelbett” zones overlapped by 50%, it was possible to send three fighters into a zone at once, but then adjacent zones would remain uncovered. Secondly, if a fighter was incapacitated or forced to return to the airfield, it took some time for another to take its place. For a long time, the staff of the 12th Air Corps did not accept pilots’ proposals for a second fighter to also orbit the radio beacon within the zone. The staff feared that the presence of a second aircraft in the “Himmelbett” zone could confuse the radar operator.
The last disadvantage was that the fighter had to return to the radio beacon after each attack to be re-acquired by the “Green Giant.” Fighters were not yet equipped with “friend or foe” identification systems, and this was the only way for radar operators to identify them.
Overall, “Himmelbett” night interception for fighters not equipped with onboard radars remained a matter of luck. Over long distances, the difference in altitude measurements of the target and the fighter, conducted by both “Giants,” could reach 500 meters. Various errors in obtaining and processing radar data could further increase this difference. Pilots often didn’t even see the target, while the red and green dots at the command post had already merged into one. It was only after more and more night fighters began to be equipped with onboard radars in the summer of 1942 that the “Himmelbett” system started to operate with the expected effectiveness.