Imagine you are a German nightfighter controller, sitting in a bunker during the Second World War. Listening posts have picked up radio transmissions from navigation beams, warning messages to British shipping, and signals from H2S or Fishpond radar devices as aircrew warmed up their equipment in England. You know the British are planning a big raid tonight and the nightfighter units have been warned. Now the first reports are coming in from observers and radar stations around the continent – large concentrations of raiders are approaching across Belgium and Northern France, heading south-east. But there’s another big force heading towards Denmark. Could they be after Berlin again?

The decisions you make next will play a significant role in the success or otherwise of the nightfighters defending the Reich. Is the force over Belgium a distraction? That’s been their tactic over the last couple of months. Or will the northern group just drop mines along the coast of Germany and scarper again? If you decide the northern threat is ‘just’ a minor mining operation you can send all your fighters to intercept the other force, which could be bound for anywhere in Germany. But then you run the risk of leaving Berlin undefended. So you might decide that the northern force is the real threat, and move your fighters to cover Hamburg from where they can quickly get stuck into any bombers crossing the top of the country. But that leaves the southern force free to attack any part of southern or central Germany untouched by fighters, should it turn out to be the ‘real’ bomber stream. Perhaps you should split your forces and send half to the north and half to the south?

This was the situation facing the German nightfighter controllers on 18 March 1944. As it happened the northern force was indeed a diversion, sent to drop mines in the Heligoland area off north-west Germany. The distraction kept many fighters to the north while the ‘real’ bomber stream slipped through almost unmolested, reaching their target – Frankfurt – having lost only four known victims to the fighters. In all the fighters accounted for just eight out of a total of twenty two casualties that night, a low loss rate probably influenced by the confusion brought about in the nightfighter control system by multiple apparent bomber streams.

A few days later two big forces of aircraft again appeared on German radar screens heading north east over the North Sea: a mining force headed for Kiel and the main bomber stream, which turned sharply south east halfway across the water. This time they flew a route that appeared to threaten cities like Hanover or even Berlin, reinforced by Mosquitos making diversion raids on both of those cities. The tactics successfully disguised the true objective of the bombers, which once again was Frankfurt (indeed, the running commentary that directed the nightfighters did not mention Frankfurt until seventeen minutes after the first target indicators went down there). Nineteen bombers out of a total of 33 that failed to return were seen to fall to nightfighters on this raid. This time the mining force did not distract the fighters unduly but the convoluted and somewhat novel route used still caused some confusion about the actual target and so the loss rate was relatively low for a city-busting raid like this one.

The Frankfurt raids demonstrate two facets of the tactics used extensively by Bomber Command in the spring of 1944 in an attempt to confuse the German nightfighter control system. Most raids carried out in this period were accompanied by aircraft on diversions, harassing raids or mining operations, and used elaborate routes designed to conceal the identity of the real target for as long as possible. On these two occasions the tactics appeared to have been successful, but there were many raids where despite the best planning and intentions, things simply didn’t turn out for the bombers as they were hoping.

One example came a few days after the Frankfurt raids, on 24 March 1944, when the Main Force bombed Berlin. They took a conventional route to the north via Denmark and were supported by Mosquitos attacking Kiel, Münster and Duisburg and a large force of aircraft from Training Groups making a diversionary sweep near to Paris without dropping any bombs. The controllers completely ignored the Paris sweep and nightfighters got stuck into the bomber stream from the island of Sylt all the way to the target and back out again. They accounted for sixteen victims – but worse was to happen to the bombers. A northerly wind that was far stronger than expected blew many crews off track and over the heavily defended areas that the route had been planned to avoid. Many, as a result, fell to flak and a total of 72 aircraft failed to return. The best-laid plans were brought unstuck by nature.

Perhaps the most infamous case, however, was the disastrous raid on Nuremberg a week later, on 30 March 1944. The bombers were routed from England down towards Charleroi in Belgium. There they would turn east for a long leg of some 250 miles, which was planned to thread the bombers safely between the heavy defences in the Ruhr and those of Koblenz to the south. The main force was to be supported by a group of Halifaxes simulating a large force possibly threatening Berlin that would actually drop mines in the Heligoland Bight before returning home, and small forces of Mosquitos to bomb Aachen, Cologne and Kassel as diversions from the main raid. The Germans decided, correctly, that the diversionary raids were just that and concentrated their fighters at two radio beacons between Cologne and Frankfurt. Unhappily for the bombers, their route passed smack between both beacons. Updated winds broadcast to the bombers were incorrect and many were off-track as a result, scattering the stream. In clear conditions over a very thin layer of low cloud, lit by a bright half-moon, and trailing spectacular white contrails caused by an unfortunate atmospheric quirk, their progress simply could not be missed. The bombers fought a running battle all the way to the target and more than sixty of the 94 that failed to return fell to fighters.

This operation had all of the usual tactics applied to it with the diversions and indirect route, but it still resulted in the highest losses of the entire war for Bomber Command. Undoubtedly the moonlight contributed, and the unexpected contrails drew attention to the bomber stream, but luck also played a part. The German controllers guessed that the northern force was a diversion and sent their fighters to the south – and just happened to pick the two fighter beacons that straddled the planned route of the bomber stream. It was a lucky guess that brought so many fighters to the area transited by the bombers, and unlucky chance that conditions were just about perfect for nightfighting when they got there.

The choice about where to deploy their forces was one that the German nightfighter control system faced night after night. Sometimes they got it wrong, and the bombers slipped through unthreatened. But frequently they got it right, and the bombers suffered severely as a consequence. The tactical cat and mouse continued throughout the war and remains a fascinating part of the story of the bomber offensive.

© 2013 Adam Purcell

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Sources:

Details of German early-warning system from Isby, David C (Ed.), Fighting the Bombers: The Luftwaffe’s struggle against the Allied Bomber Offensive

Details of Nuremburg raid mainly taken from Martin Middlebrook (1973), The Nuremburg Raid

Frankfurt and Berlin raid details and additional information on Nuremberg from Bomber Command Night Raid Reports Nos. 556, 560 and 567.