In my opinion, the real reason for abandoning formal intruder operations was practical: cost/benefit ratio. For example, a dozen Me410s of KG51 carried out a successful, impromptu intruder attack on USAAF B-24s returning from Hamm in 1944 (see below) and destroyed 12 out of the 1662 USAAF despatched at the cost of two Me410s: a rate of loss to intruders of about 0.7% for the USAAF vs a 17% loss rate for the Luftwaffe. The latter is simply not sustainable, especially when the US could replace pilots and aircraft and Germany could not.
I'm attaching part of an assessment that I wrote for
Chandelle (text and illustrations © 2007-2008 by Robert Craig Johnson. All rights reserved):
"For all the success of the intruder tactic,
Luftwaffe adoption of intruder tactics was limited by the exigencies of supply and political necessity. The
Himmelbet system was successful in large part because it, for the most part, did not compete for aircraft and aircrew with better established arms of the service. The Messerschmidt Bf110 was thus entirely adequate. But the intruder role required an aircraft and crew capable of locating a point at a considerable distance from home and then operating for an extended period over hostile territory. An altogether larger, bomber-sized aircraft with a highly trained, bomber-type crew was thus essential.
"As it happened,frontline demand for aircraft and skilled aviators far outstripped Germany's ability to produce either in wartime. For all its initial successes, Germany was, relative to its opponents, a fairly small and under-industrialized country with few natural resources and a modest population. It counted on a short war, in which scarcities and wastage could be made up quickly using captured enemy equipment and supplies. The
Luftwaffe training organization was dwarfed by its counterparts in the British Commonwealth and the United States. It depended in large part on obsolete or captured French, Czech, and Dutch aircraft and engines for its equipment. When hopes for a short war and an advantageous peace began to evaporate, a tactic that concentrated scarce airframe materials, engines, and trained crews in a few sophisticated, long-range aircraft could not be sustained. As the frontlines began to constrict around Germany, the choice had to be made between a larger, less intensively trained force of fighter pilots and single-seat fighter-bombers—or a larger number of of infantry with tanks and small arms—that could directly affect events on the battlefield and a smaller number of intruder aircraft and crews that might modestly reduce the scale of Allied strategic air attacks. The
Fernachtjagd had become a luxury in a time of want.
Politically, reliance on intruders was equally unsustainable in a long war. Once Allied air raids ceased to be a mere annoyance and began to ruin German cities and massacre their inhabitants, the country's political leadership could not simply defend the country: the regime had to be
seen to defend the country. Bombers destroyed over East Anglia—or in remote
Himmelbett boxes for that matter—did nothing to bolster public morale. Given the scarcity of twin-engined night fighters and crews, Germany's leadership had to choose between short-range home defence—which could be seene—and
Fernachtjagd. The
Fernachtjagd was an unjustifiable luxury in this instance as well.
After 1942, the
Luftwaffe's long-range night fighter units were reallocated to more pressing, more conventional duties. Many were pulled back to the frontiers of the
Reich and used as dedicated interceptors and ground attack aircraft. Others were assigned as long-range fighters over the Atlantic or for local, tactical support on the Mediterranean and Eastern fronts. Late in 1941,
NJG II left Gilze-Rijen for Catania in Sicily, whence it supported the Italian German air assault on Malta and provided cover for Rommel's beleaguered supply convoys. Small detachments were soon scattered across the theater as immediate tactical necessity dictated, from the Bay of Biscay and the French Mediterranean coast in the north and west to Benghazi in the south and Crete in the east.
Given the economic and geographical realities facing Germany once Britain refused a separate peace and once the USA and USSR became belligerents, the reassignment of a few long-range intruders could not be expected to materially alter the outcome. Accordingly, in 1944, as the war situation worsened and Germany's inability to alter her situation by mass production and mass mobilization became increasingly clear,the potential efficiency of intruder tactics once again attracted notice, this time from a seemingly unlikely source, the then under-utilized
Luftwaffe fast bomber formations in France, which had just converted to an aircraft that could be spared for intruder duties, having proved unsuitable and/or unpopular in other, higher-priority roles: the intended successor to the Bf110
Zerstorer, the Messerschmitt Me410.
The Me410 was an unfortunate airplane developed against a dated and over-demanding specification by too few engineers at a time when other projects were already taking priority. By the time it appeared in numbers, it was largely obsolete. The Me210, as the aircraft was first known, suffered from intractable handling difficulties that were solved only with time, testing, and major redesign. By the time a satisfactory version appeared as the Me410, it was too slow to survive as an unescorted day bomber or reconnaissance aircraft. While handling characteristics were acceptable, maneuverability was inadequate, even for a twin-engined fighter. The Me410 could not have held its own against Mosquitos and Beaufighters and its 1450-mi (2333-km) range was not outstanding, so it had few attractions in the maritime role. The
Nachtjagd chose to soldier on with the Bf110G. As a heavy interceptor of unescorted day bombers, the Me410 was relatively successful for a while but still proved more vulnerable to the heavy defensive fire of American bomber formations than its single-engined counterparts. When long-range, single-engined American escort fighters appeared over the Reich in 1943, its usefulness in this role came to an abrupt end as well.
By 1943, however, the Dornier Do217, the mainstay of the
Kampgeschwadern in the West, was proving too vulnerable for operations over the British Isles, even at night. Dorniers were valuable for antishipping and escort work over the Mediterranean and the Bay of Biscay and could not be thrown away in what were, by now, token propaganda missions. So, to sustain limited operations against the United Kingdom at minimum cost, V/
KG 2 and elements of
KG 51 converted to the Messerschmitt Me410A-1 and B-1 subtypes, which were configured as fast light bombers. The Me410 had a bomb bay that could hold a normal load of 1100 lbs (500 KG) and could reach a top speed of 388 mph (624 kph)—ideal for the campaign of high-speed, low-altitude nuisance bombing that would become known as the "Baby Blitz". Since the multirole Me410 design included a standard fighter-type, fixed, forward-firing armament of two 20-mm MG151 cannon and two 7.92-mm MG17 (Me410A) or 13-mm MG131 (Me410B) machine guns, the aircraft could also operate as an intruder. This latter role proved successful enough that, by 1944, V/KG2 and I and II/KG51 were operating many of their aircraft as dedicated Me410A-1/U-2 fighters, with an additional pair of 20-mm cannon installed in the bomb bay in a
Waffenbehalter 151 weapon pod.
On the evening of 22 April 1944, a dozen or so Me410s from
KG 51 followed bombers of the US Army Air Force 8th Air Force home from a raid against the railroad marshalling yards at Hamm in Germany. The Americans had despatched a mixed force of 803 B-17 and B-24 bombers against the target, accompanied by an escort of no less than 859 P-38,P-47, and P-51 fighters. Losses were relatively modest over enemy territory—eight B-17s and seven B-24s shot down with one B-17 and 14 B-24s damaged beyond repair, plus two P-38s, five P-47s and six P-51s lost and one P-38 damaged beyond repair. But, as the mission progressed, succeeding units seem to have had increasing difficulty locating the target. The B-17s went in first, and 459 of 526 found the target, while only one attacked an unidentified target of opportunity. But only 179 of the 2nd Air Division's 277 B-24 Liberators bombed the primary target, while 50 diverted to the secondary, Koblenz, and 36 attacked unidentified targets of opportunity. This seems to have disorganized the time table for the return flight and scattered the final USAAF formations. As dusk fell, the 389th and 458th Bomb Groups were still well short of their East Anglian bases, and
KG51's Messerschmitts had successfully infiltrated their ranks, where the latter could not be detected by ground-based radar. The fighters attacked just as the B-24s were entering the landing pattern at about 2200 hours. Tracer was seen from the airfield control tower, so the alert was given immediately and the airfield blacked out. In the resulting melee, the Me410s shot down 12 B-24s in a matter of minutes. A B-24 waist gunner shot down Me410 9K
+HP (
werke number 420458) at Ashby St. Mary, and air gunners and/or airfield antiaircraft guns damaged 9K
+MN (
werke number 420314) severely enough that it never returned to its base in France. Many B-24s were damaged by friendly fire, as gunners fired wildly at half-seen aircraft in the gathering darkness.
By 1945, diminishing fuel reserves, heavy losses, rapidly contracting fronts, and Allied electronic countermeasures (ECM) severely restricted the effectiveness of the conventional
Luftwaffe night fighter arm and forced a more determined return to intruder tactics. Noise jamming and mass deployment of
windows and
chaff (radar-reflecting strips of reinforced aluminum foil) had largely blinded German air and ground radars, while heavy communications-jamming crippled the ground-controlled fighter-direction system. Since twin-enigned aircraft lost much of their advantage under such conditions and were more vulnerable to the aggressive, radar-equipped Mosquito intruders that now accompanied RAF bomber streams, single-seat
Wilde Sau fighters increasingly took on the nocturnal interception tasks once reserved for heavy
Zerstorern. But the long range and navigational facilities offered by the mainstay of the conventional
Nachtjagd, the Junkers Ju88G, could still be used to effect over Great Britain, where few
Luftwaffe aircraft were expected to venture this late in the war.
In January, the German night fighters played a limited role during the
Bodenplatte attacks on Allied forward airfields, serving as ground attack and pathfinder aircraft. This seems to have inspired a similar strike against RAF Bomber Command bases, Operation
Gisela, the first and last attempt to mount a coordinated, mass intruder operation over the British Isles. On the night of March 3/4, 1945, with the Red Army on the outskirts of Berlin and the end of the war just weeks away, 142 Ju88G night fighters from I, II, and II/
NJG 2, II and IV/
NJG 3, III/
NJG 4, and III/
NJG 5 followed some 500 British heavy bombers home from a raid on the synthetic oil works at Kamen and the Dortmund-Ems canal. The night fighters skimmed the waves, relying on newly fitted radar altimeters, or mingled with the bomber stream to avoid detection by British early warning radar. At this late date, RAF aircrew were apparently becoming complacent and were remarkably lax once they crossed the English coast. Many turned on their navigation lights and left them on, even after being warned that intruders were a possibility. At least some of the intruding night fighters did likewise in the hopes of being mistaken for friendly aircraft. The result was pandemonium. Bomber Command bases across Yorkshire turned off their lights and closed their runways, leaving panicky aircrew to mill about for some two hours while searching for alternate landing fields. While only nine aircraft had been lost over the Continent that night, nineteen were shot down over Driffield, Dishforth, Brafferton, Elvington, Sutton-on-Derwent, and Knaresboroug. These included:
- eight Halifaxes of 4 Group
- two Lancasters of 5 Group
- three Halifaxes, one Fortress, and one Mosquito of 100 Group*
- 2 Lancasters and 2 Halifaxes from Heavy Conversion Units**
Both the most experienced and least experienced formations suffered losses. 100 (Bomber Support) Group was the RAF's elite electronic countermeasures and offensive night-fighting unit. The Heavy Conversion Units were primarily training formations that had merely mounted diversionary attacks in support of the main force. Five additional training aircraft were shot down or lost to accidents while engaged in routine, local night-flying training.
Heavy as RAF losses were, German losses were worse: 25 Ju88s. At least three intruders collided with the ground during low-level strafing runs. The remainder fell to the guns of the Mosquito night fighters that eventually swarmed to the scene. While many commentators have argued over the years that earlier adoption of
Gisela-style tactics might have crippled the RAF's strategic bombing campaign, the mission was a clearly such a disaster for the
Luftwaffe that
Gisela would not and could not have been repeated. Even a healthier air arm than the
Luftwaffe could not sustain over 12% losses per operation for any length of time. The
Nachtjagd was never large to begin with—it mustered perhaps 600-700 aircraft at its height, of which some 350 were long-range Ju88s. Heavy losses during
Bodenplatte and subsequent nocturnal ground attack sorties significantly reduced its numbers below these figures. All but continuous, day and night attacks by Allied fighters and fighter bombers (including
Firebash nocturnal napalm strikes on
Luftwaffe airfields) exacted an additional toll. These losses, combined with fuel shortages and the rapid approach of the front lines made any repeat of
Gisela impossible. Moreover, what success
Gisela achieved was due largely to the long absence of enemy intruders over Britain. Had such operations been more common, it is likely that the RAF would have been less complacent and less slow to react. The bombers might have suffered less severely, while the attackers might have suffered more grievously than they did, given the technical ascendency of the RAF night-fighting arm at that time.
As it was, the
Luftwaffe managed to mount only a few small-scale intruder operations in March and April 1945. The
Nachtjagd was by then a spent force, and
Gisela was, effectively, the last notable operation by a German night fighter arm that would disintegrate in a mere matter of weeks, as its personnel were drafted and sent piecemeal into pointless skirmishes or allowed to slip away quietly and return home to await the inevitable.