Bomber Command’s Battle of Berlin was the First Electronics War in Aviation History

There were two key questions that needed answering if Bomber Command was to achieve success in the Battle of Berlin. First, could it mark the target accurately and concentrate the bombing effort; and second, could it keep the Luftwaffe at bay and maintain a loss rate of below 5 per cent?

Arthur Harris, chief of RAF Bomber Command, had long been convinced that his heavy bombers could force Nazi Germany’s surrender — if only enough of them could be unleashed against its cities. In late 1943, he seized the last chance to prove his theory. The target would be Hitler’s capital.

The Battle of Berlin was a hard, desperate slog, fought in bitter winter weather. Over 16 major raids, Bomber Command and the Luftwaffe’s night-fighters attempted to outwit and outfight the other.

As told by Richard Worrall in his book Battle of Berlin 1943-44, there were two key questions that needed answering if Bomber Command was to achieve success in the Battle of Berlin. First, could it mark the target accurately and concentrate the bombing effort; and second, could it keep the Luftwaffe at bay and maintain a loss rate of below 5 per cent? The issue of bombing navigation and accuracy had bedeviled bomber operations right from 1939 and, in an attempt to improve this, led to the creation of the PFF in mid-I 942. But there were also devices that had helped improve Bomber Command’s accuracy. The first was Oboe, which was used by high-flying Mosquitos, and the most accurate means of blind bombing so far devised, but it was limited geographically and it could not reach Berlin owing to the curvature of the earth. The second technical gadget was H2S, which was a ground-echoing radar carried in the aircraft. Effective over small cities and against ports, such as Hamburg, because of the sharp contrast between land and sea, H2S was more problematic the further inland it went. It became imprecise and difficult to decipher over built-up areas. There were high hopes for H2S over Berlin in August 1943 after the experience over Hamburg, but Berlin was simply too big and filled the H2S screen, making any distinction impossible. However, Harris had little alternative but to persist with trying to make H2S work, given that Berlin lay beyond the range of the electronic navigation and bombing system of Oboe or the radio navigation system, increasingly susceptible to German jamming, of Gee. Consequently, ‘blind marking’ on H2S was seen as the way to mark targets during the Battle of Berlin, which was asking a lot of this equipment. And the definition of Berlin under the new H2S Mk III, which Harris had eagerly awaited before recommencing the offensive against the German capital, proved little better than the original Mk II set. The alternative was to mark the target using the Newhaven technique — laying masses of flares to allow visual identification of the aiming point — but this technique required good visibility both for the Pathfinders and the Main Force, and such conditions were scarcely ever seen over Berlin during autumn and winter.

In terms of the second issue, that of neutralizing the Luftwaffe, the Battle of Berlin proved to be a war of electronics between Bomber Command and the Luftwaffe. In particular, the British made significant improvements in RCM throughout 1943 and these various methods would be brought together against the German defences in the Battle of Berlin. The older countermeasures of airborne and ground-based Mandrel to jam the frequencies of Freya — a ground-based early warning radar —and the British electronic device called Tinsel to jam German High Frequency Radio Transmitters (HF/RT) were still in use. Above all, it was Window that had become the principal countermeasure to enemy radar and was dropped by the whole bomber force. The use of Window for decoy purposes had been rapidly expanded since its Introduction in July 1943 and major raids would be usually accompanied by one or more decoy attacks by Mosquitos. 101 Squadron operated Airborne Cigar (ABC), in which Lancasters were fitted with jamming equipment and had an eighth, crew member — a German speaker — who listened to enemy radio instructions to the night-fighters and jammed their frequency using a VHF transmitter. ABC Lancasters would fly throughout the bomber-stream and would represent a continual problem for the Luftwaffe. Ground Cigar did a similar thing to jam VHF/RT. Then there was Corona, which involved the transmission of fake instructions — such as the order to land because of fog — to interfere with the running commentary of night-fighters by a German-speaking operator from a radio station in Kent. Both these RCM would be introduced in October and would be used throughout the Berlin campaign. Two new measures, Dartboard and Drumstick, would be introduced in December 1943 and January 1944 respectively. The first was to jam the high-powered transmitter at Stuttgart, which was used by the Germans to transmit a running commentary when their original transmitters were jammed by Corona. The second was to counter wireless transmissions which were resorted to by the enemy controllers when RT communication was jammed.

To hunt night-fighters more aggressively, 141 Squadron of 100 Group developed a device called Serrate that homed in on the electronic emissions from German night-fighters using the Lichtenstein radar device. These so-called Intruder operations first took place on Dec. 16-17, 1943 and would do much to erode the German night-fighters, particularly among the elite Nachtjagdgeschwader 1 (NIG-1) that was based in the Low Countries. 100 Group would also deploy other devices such as Mandrel, which was used for jamming the Germans’ early-warning radar. Such were the technical devices the British had to develop in order to counter the increasingly assertive Luftwaffe. Yet in this ‘electronics war’ with the Germans, it was not all good news for the British. Evidence increasingly accrued that the more devices carried by British bombers, the more like ‘beacons’ they became for the Germans, who developed the ability to home in on H2S emissions and thereby identify the bomber-stream’s location behind the Window screen. Night-fighters could also do the same to other devices such as Monica (a warning device of an aircraft approaching the bomber from behind and below) and Fishpond (a fighter warning radar added on to H2S).

Battle of Berlin 1943-44 is published by Osprey Publishing and is available to order here.

Photo credit: Piotr Forkasiewicz (www.peterfor.com) Crown Copyright and German Federal Archive