The radar-based German fighter defense system was always oversaturated and nearly invalidated by the bomber streams and by the new electronic countermeasures systems, including Window (chaff). On 27 June 1943, Major Hajo Hermann proposed to the commander in chief of the Luftwaffe, Hermann Goering, that night-fighter defense tactics be modified to a radical new scheme. This was the so-called Wild Boar plan that allowed the concentration of masses of single-engine day-fighters against the bomber streams independent of radar guidance. By using searchlights and flares for illumination and direction-finding, and by exploiting the fact that the bombers could easily be recognized against the clouds over burning cities, the fighters could make contact without radar.
Major Hajo Herrmann had been one of the most famous of the Luftwaffe bomber pilots, with an already incredible record of accomplishment. In early 1943 he was at staff college, fuming at the fact that each night the Reich was being defended by grossly overworked night fighters while hundreds of single-seaters stayed on the ground. He made out to Kammhuber a powerfully argued case for what was virtually a return to the old Helle Nachtjagd system. Herrmann was a man of influence far above his rank, and he explained how readily he could build a potent night force of single-seat fighters that would not be part of the regular day (JG) wings but manned by skilled former bomber pilots, all men used to flying at night and toughened by years of action. In his view such a man flying a 109 or 190 could find enemy bombers at night, especially over the glow of a burning city. Searchlights would be invaluable, and he considered that such experienced pilots ought to be able to destroy every bomber held in a searchlight cone for as long as two minutes. But Kammhuber had patiently constructed a formidable defence based on close GCI Himmelbett control. Fighters ranging uncontrolled among the Flak bursts seemed a terrible idea, even though Herrmann stressed that he wanted to fight not in place of the NJG force but in addition to it.
Getting nowhere with Kammhuber, he did not give up; he just went over his head, straight to Generaloberst Weise. Weise had no vested interest in the Himmelbett system, and felt that every little helped, especially as Herrmann had secured a verbal agreement from the Berlin Flak commander to restrict gunfire to below an altitude of 5 km (16,404 feet), giving the fighters a safe region above; and presumably other Flak divisions might do the same. Weise gave permission for trial operations, and Herrmann gathered his forces to practise what he called the Wilde Sau (wild boar) method. It was intended to be simple and effective. The single-seaters would be standard except for carefully flame-damped exhausts and, in some cases, the fitting of Naxos-Z homers. The main Wilde Sau fighters were the Bf 109G-6/U4N and Fw 190A-5/U2N. The name of the unit was the Kommando Herrmann, and there is no doubt that – quite apart from whatever else it achieved – it exerted an inspiring effect on the regular NJG forces. Herrmann’s ex-bomber pilots were imbued with their leader’s fanaticism. One way in which this was manifest was in their flight planning, which was based on continuing each mission until the tanks had practically run dry. The heavily armed single-seaters carried no external fuel, and endurance was very limited. It may have been deliberate policy to eschew such a nicety as being bothered about the fuel state, because in the course of the winter 1943–4 this became increasingly the general policy among the NJG units as well. Night fighters were now pouring off the assembly lines. So long as the crew got away with it, a dead-stick landing in the dark that destroyed the aircraft was of little consequence. Indeed, the most remarkable factor was the high proportion of pilots who did manage to regain an airfield runway.
The Kommando Herrmann began operations in the Essen/Duisburg area in June 1943, and had their first big chance on 3 July, when the target was Cologne. Undeterred by the fact that he had not notified the local Flak division, Herrmann and eleven of his pilots spent two hours among the intense shell bursts and shot down twelve bombers. Next day Herrmann found himself a national hero; he was instantly summoned to Karinhalle, where Goering authorized him to form a full Wilde Sau wing, designated JG 300 (not, it will be noted, NJG). It put Kammhuber in a difficult position. In the Nazi environment of constant intrigue it might have served him best to decide that, if he couldn’t beat Herrmann, he would join him (by publicly joining in the chorus of adulation). He chose instead to stick to his rigid and narrow doctrine of close radar control, and to call for a further increase in radar production. Little did he know what was just around the corner.
The new tactics required boldness because the German antiaircraft artillery were already firing at the bombers, but it proved very successful as a last resort after German radar was blindfolded by Window as of 25 July 1943. On the basis of this success, Hermann was ordered to establish the “Wild Boar” Fighter Geschwader 300. He later became commander of this unit and of the 1st Fighter Division.
On the afternoon of 24 July 1943 the crews of over 800 RAF bombers were briefed to attack Hamburg. During the briefing they were at last told about Window, and that night the 746 aircraft that bombed also released about 92 million strips of foil. The result was chaos. Ground controllers, night fighters, master searchlights and Flak were thrown into frantic confusion. Only twelve aircraft were lost, and those tended to be either low-flying Stirlings or the highest-flying Lancasters, cruising outside the main Window cloud. Just a few Himmelbett stations and NJG operators managed, partly by luck, to pick off from their crowded and flickering display screens the vital blip that appeared to have a motion different from the rest. But Window made no difference to Herrmann. In subsequent attacks in the ten-day battle that destroyed Hamburg, his single-seaters moved to the area and destroyed more than fifteen bombers, while others fell to NJG crews operating in the same freelance way. Some of the bombers were seen from below, dimly reflecting the light of the burning city. Some were seen from above, silhouetted against the fires, while others were spotted against the numerous searchlight beams pointing out the bombers’ track almost horizontally along the ground. It says much for the courage and tenacity of the German pilots that they were able to inflict many casualties by the same crude methods that had proved so ineffectual over Britain in 1917 and 1940. But one is not comparing like with like: over Germany in 1943 the bombers were bigger and much more numerous, and the amount of illumination on the ground and in the sky was immeasurably greater. Both RAF and Luftwaffe aircrew were hard-put to retain their night-adapted vision in the midst of such an inferno. (It was in theory a court-martial offence for Bomber Command aircrew to look at the glowing target.)
Great as was the confusion caused by Window, it was not the only countermeasure used by the RAF. The awareness, ingenuity and fast action of the TRE, Bomber Support Development Unit and other organizations had already begun a succession of ECM developments that henceforth kept the Luftwaffe perpetually off-balance. One of the first was Mandrel, a powerful airborne radio transmitter that broadcast intense noise interference on the exact frequency of Freya. Defiants, pensioned-off from night fighting, orbited bravely near the outer reaches of the Kammhuber Line with Mandrel instead of armament, taking out a section up to 200 miles wide during major RAF attacks. The heavies themselves were able to carry the jamming across Germany, because a Mandrel transmitter was installed in an average of one bomber in every squadron. To blot out GCI communication between the Himmelbett stations and the NJG fighters most bombers also carried Tinsel. This was simple and effective: the ordinary TR 1154/1155 radio was tuned to the German controller’s wavelength and arranged to broadcast from a microphone bolted inside one of the bomber’s engine nacelles. With Wilde Sau tactics, in a sky full of Window, everything depended on guiding the fighter in among the bombers. The Luftwaffe reacted violently to Mandrel and Tinsel, investigating ways of making the newer Mammut and Wassermann early-warning radars resistant to jamming, and building powerful new HF and VHF radio stations for broadcasting to the night fighters – all of them, not just the single-seaters. The RAF responded with Special Tinsel; monitors in England listened to the GCI traffic and radioed each new frequency to the attacking force, which then jammed it as before. To smother the VHF frequencies, 101 Squadron Lancasters sprouted tall mast aerials to broadcast jamming from ABC – Airborne Cigar – an extremely powerful VHF transmitter manned by a special German-speaking operator who listened to all VHF transmissions until he or she found the GCI frequency.
This was still only the beginning, for there was even more that the RAF could do. For months the possibility of sending the RAF’s own night fighters over Germany had been discussed, but as the majority of possible targets they might find were RAF heavies there were obvious snags. Of course IFF would help, but how could they be made to home on to the Luftwaffe night fighters? The answer was provided by TRE within a week of laying hands on the Lichtenstein-equipped Ju 88 that landed at Aberdeen. They devised Serrate, a small receiver tuned to 490 MHz and displaying any received signals on a cockpit CRT. The observer saw a display like a gappy herringbone; the bones became longer as the range closed, and moved up or down the display. When the fighter was heading straight for the German night fighter the bones were equal in numbers and length on each side of the vertical time-base. Serrate was issued first to 141 Squadron at Wittering, equipped with early Beaufighter VIF aircraft that still used AI.IV radar. Radar was essential, because Serrate did not positively indicate range. Under aggressive Bob Braham No. 141 began a few weeks of startlingly successful intruder operations, mostly over Holland, but after destroying 23 Luftwaffe night fighters the work was halted in September, because there were insufficient customers. By this time No. 141 was achieving a kill every 35 sorties, on average.
Wilde Sau (Wild Boar) was a tactic involving fighters roving at will without radar, intercepting by visual contact in cooperation with German ground anti-aircraft artillery. Initial successes with Wilde Sau were soon reversed by heavy and mounting losses and the technique was dropped in March 1944.
If the cloud ceiling at the time of the attack too high, restricting the lighting effect, the optical conditions were insufficient to apply Wilde Sau. The success of the attacks was also lost with the onset of bad winter weather in late autumn 1943, when wastage through accidents and icing soared. German pilots were always at risk from their own anti-aircraft fire. Even if “Wilde Sau” were also partly accomplished by twin-engine night fighters, the bulk of the action was carried out by conventional day fighters borrowed from the day Jagdgeschwaders. This double load of daily and night operations and the resulting erratic maintenance schedules meant fighter servicability rates dropped drastically.
A leading Experte, Oberst Viktor von Lossberg, had argued for NJG units to infiltrate into the bomber stream before the heavies even reached the coast, and he transferred several squadrons to the Scheldt estuary and north German coast. Under the name Zahme Sau (Tame Boar) he proposed a freelance running fight with the NJG force to partner Herrmann’s Wilde Sau single-seaters which concentrated over the target. An integral part of Zahme Sau was to use the RAF’s own Window to confirm the position and track of the bomber stream. The technique recognized that under the new circumstances the Himmelbett system was useless, except to get the odd straggler that strayed out of Window protection. The answer seemed to be loose control, with fighters flying perhaps right across Germany, instead of staying in a neat little box, and fighting until they ran out of fuel. It was essential for the GCI controller to use every wile and sixth sense to try to divine the bombers’ target in advance, and to note every turn made by the leading sections in the bomber stream. Co-operation with Flak was essential, and one of the recurrent problems was that the free-ranging fighters were often running into intense Flak.