Script for War Room: Raid on Bohlen, 1945 (Patreon)

Well, having said I didn't like the script for this and that I would tackle something else... it turned out to be much quicker and easier to fix the script that start afresh. Definitely feels better with the maps etc to go along with it.

***

War Room 25: Raid on Bohlen, 1945

Welcome back to the War Room where we are going to take a look at a Bomber Command raid on the night of the 20-21st of March 1945. This is a really interesting night for a few reasons.

The first is that it showcases a mature system. RAF Bomber Command went into World War Two with a lot of pre-conceived notions about the mechanics of long distance bombing raids and basically discovered that they were all wrong. Through the war, they not only had to adapt to the newly discovered realities but continue to adapt as they competed against the reactions and adaptations of the German air defence network.

By 1945, the RAF had won that battle. Bomber Command could strike any target it wanted within the limits of range and weather conditions- the Luftwaffe couldn’t stop it. This doesn’t mean that there were no losses or that German flak and night fighters could not shoot down Bomber Command aircraft, but the attrition rate was not enough to stop the RAF going out at every opportunity and hitting something in Germany.

The second reason why this is interesting is because it is surprisingly modern. There are naturally some technical differences because of the intervening time, but if we replace bombers with cruise missiles, flak with surface to air missiles and window, or chaff, with decoys we’re not far away. There are very similar mechanics here and thus some insights into more recent, or indeed ongoing, operations.

This isn’t a tremendously well known mission, I’m getting most of my information from Instruments of Darkness: The History of Electronic Warfare, 1939-1945 by Alfred Price. It’s an excellent book, super interesting if you want to get a handle on early electronic warfare and how sophisticated it had gotten by the end of the World War 2.

Background

Bohlen is in East Germany, about 150km south west of Berlin and 15km south of Leipzig, and was the site of one of Bomber Command’s two targets for that night: a synthetic oil plant.

At this time Bomber Command’s main operational method was to attack by means of a bomber stream: as many bombers as available would proceed to the target in a kind of loose column or ribbon that would allow them to oversaturate the German air defence system at the point of penetration. This also allowed them to minimise the amount of time there would be bombers over the target- decreasing the time the defenders had to react and helping to ensure a denser concentration of bombs.

Out in front of the main stream would be pathfinder aircraft equipped with radio and radar navigational aides, which would find the target and mark it with coloured flares for the rest of the bombers to find. In support, there would be night fighters, to counter German night fighters, as well as aircraft deploying various kinds of radio and radar countermeasures intended to disrupt and degrade the German response to the raid, essentially early electronic warfare aircraft.

To simplify somewhat, on these raids Bomber Command is trying to conceal the strength, direction and speed of the bomber stream so that they can strike their target and get back, while the Luftwaffe is trying to figure out where the bomber stream is and where it’s going so they can vector in night fighters to intercept. There are still flak and searchlight batteries defending specific locations, but the night fighters are the reactive arm of the defensive system.

Take-Off

The night of the 20th March begins with a nuisance raid. 35 Mosquitos penetrate the German air defence network and head to Berlin to start making trouble. There’s not much the Luftwaffe can do about this: diverting night fighters from elsewhere in Germany to help defend the capital wouldn’t help much- the Mosquitos are extremely fast and hard to catch- and could leave other sectors vulnerable if Bomber Command stages a major raid elsewhere.  The nuisance raid itself is not a good indicator that there will be a major raid, because the RAF does this every night it can.

Obviously on this night there is a major raid coming: the main strength of this assembles over Southern England and heads south over Allied-occupied France at about 0100.

Out in front, screening the bombers, are 14 Halifaxes equipped with Mandrel jammers. Mandrel was a device that transmitted on the same frequencies used by German ground-based radar systems, particularly Freya and its derivatives. It was a relatively old system by the time of the Bohlen raid and could only broadcast inside a 10 MHz range, which covered the range that Germany’s Freya radars used when it was introduced at the end of 1942.

But the Luftwaffe operators soon found they could fine tune to avoid the worst of the jamming and it didn’t take long for Freya-type radars were upgraded to operate over a wider range of frequencies. The RAF in turn countered this by using larger aircraft as dedicated jammers, each carrying several Mandrel devices to jam more of the frequency spectrum.

By the time of the Bohlen Raid, they were using Halifax bombers carrying 8 Mandrels each, operating in pairs. These were spread out on a line 130km across, creating a wall of jamming on a wide range of frequencies that the German air defence network couldn’t see through.

Behind this jamming screen, the main element of the raid was a force of 235 Lancasters and Mosquitos, but there were another 64 aircraft crossing the Channel at the same time. We’re going to call this force Feint 1: it’s actually a training flight. By heading out over France and ultimately towards Strasbourg, the crews can get some realistic long range night flying experience without the risk of enemy interference- unless they get very lost- and they can contribute to the deception plan.

So already we have three components making life difficult for the German air defence system. We have a jamming screen degrading their radar. If they manage to see through that, they’ll pick up two flights of aircraft, either or neither of which could be the RAF’s main effort for the night.

To make life even more complicated, at 0155, 41 Lancasters from the main force split off and start to head north east. We’re going to call this force Feint 2.

Around about the same time, 14 Mosquitos cross into Germany and head to airfields likely to be used by Luftwaffe night fighters that night. Activity at these airfields was hard to hide- there was always going to be some light necessary for take-offs and landings, ground crew work and vehicle movement. The job of the Mosquitos was to hang around these airfields and shoot up or bomb anything they saw- to include the German night fighters themselves as they came and went.

Again, this a common operation for the RAF, it’s not directly linked to major raids, so the presence of Mosquito harassing missions is not a solid indicator that something will happen.

Penetration

At about 0300, the Main Force and Feint 2 emerge from the jamming screen thrown up by the Mandrels and start to cross the German frontier, while Feint 1- the training flight- approaches Strasbourg to the south.

This is all in the Luftwaffe’s Central Rhine defence area: all three formations of incoming bombers are picked up by German radar and reported to the night’s controller: a Major Heinrich Rüppel. Rüppel now has to try and work out which of these three contacts is Bomber Command’s main effort and do so fast enough to redirect his 90 or so night fighters to positions where they can intercept it, but not so fast that they will be caught out of position if he’s wrong or the bombers change course.

Of the three, he’s able to quickly discard Feint 1 when the training flight turns around at Strasbourg and starts to head back into France.

The two northerly contacts are more problematic: some of the leading aircraft in both formations have started dumping window, otherwise known as chaff. Window is made up of long thin strips of aluminium foil. If dumped in large enough quantities, these create their own radar return that can serve to mask the radar returns of nearby aircraft.

In practice, this means that Rüppel can’t determine the relative sizes of the Main Force and Feint 2- their true strengths are concealed by window. To begin with, he thinks that both forces are feints. It was not uncommon for Bomber Command to make minor incursions with aircraft deploying window to complicate the German air defence picture.

But radar is not the only information gathering tool available to the Luftwaffe at night. They also have observer teams deployed across Germany. Obviously these are more useful against the US Army Air Force’s daylight raids, but while it’s harder to spot aircraft flying overhead you can definitely hear them.

And the 200 or so aircraft of the Main Force to the south make an awful lot more noise than the 40 aircraft of Feint 2.

This leads Rüppel to correctly identify Bomber Command’s main force, now he needs to work out where it’s going. The main force is initially travelling straight at Frankfurt, but then it alters course north east as if it’s going towards Kassel.

Rüppel makes the call the direct his night fighters to three radio beacons around that city: Komoran, Silberfuchs and Werner, with a few night fighters diverted to beacon Otto near Frankfurt just in case.

At 0308, reports start coming in of aircraft and marker flares over Kassel, confirmed via radar which has tracked the contact all the way to the city. Bomber Command uses marker flares to indicate targets at night.

The advance aircraft of the bomber stream, usually specially equipped Mosquitos and Lancasters, accurately locate the night’s targets using H2S, which is a ground scanning radar, and by navigational aids like Gee and Oboe, which used radio and radar respectively to guide aircraft onto their targets. Once in position, the Pathfinders would drop multi-coloured marker flares to indicate the target’s position for following bombers without the same specialist equipment. Different colours or sequences of colours were used to indicate target locations identified by different equipment- Oboe, for example, was by far the most accurate so bombers would be instructed to prioritise striking the night’s Oboe markers. They could also, as in the case at Kassel, be used to indicate false targets marked as part of the night’s deception plan.

The whole concept of the Bomber Stream was that all the bombers would pass over the target quickly, so they couldn’t be far behind the Pathfinders, so markers over Kassel are everything Rüppel needs to order all his night fighters to converge on that city and intercept the RAF’s main force. One of them detects, engages and shoots down a B-24 Liberator, but the main force never arrives.

The RAF aircraft over Kassel were the lead elements of the main force, but they continued on to the city while the rest of the Bomber Stream made another turn to the north-east. So now we have Feint 3, which has not only continued to dump window on its approach to Kassel in order to disguise its strength and the turn made by the main force, but has been reinforced by another 12 Mosquitos to help with the fake target marking.

Nevertheless, the Bomber Stream and the Night Fighters are in relatively close proximity. One Bf110 gets close enough to the main force that it’s engaged by one of the Mosquito night fighters protecting the flank of the bomber stream.

The main method of night interception used by the Luftwaffe is for a ground radar station to guide a night-fighter to the bomber stream, at which point the fighter can take over the engagement with its own active and passive radar systems. But to do that, the ground controllers need to be able to determine which contact is the night fighter and which contacts are the bombers. The result was that Luftwaffe night fighters were fitted with an early Identification Friend or Foe system, which would return a specific signal when prompted.

The RAF, meanwhile, had developed a series of countermeasures. Not only were bombers equipped with rear-looking radars and radar receivers that would alert the crews to other aircraft coming up behind them or painting them with radar- a device known as Monica- but RAF night fighters were equipped with Serrate, which allowed them to detect and home in on emissions from German night fighter radars, and a device called Perfectos, which would ping the IFF system used by Luftwaffe night fighters and get back the precise location data needed to intercept them at night.

In this case, Perfectos allowed a Mosquito to shoot down the BF110.

Time Over Target

The Luftwaffe fighters orbit Kassel for a good twenty minutes, waiting for the bomber stream to arrive: it’s not until 0330 that Rüppel figures out it’s a trick and orders his night fighters towards Leipzig, which has been identified as the next possible target.

Bohlen is not far to the south, but the RAF isn’t out of tricks yet.

Just west of Leipzig is another important German oil refinery- the plant at Leuna. Yet another element splits from the RAF main force at about 0320, and by 0340 marker flares are dropping over both Bohlen- the actual target- and Leuna- now Feint 4.

Heading directly towards Leipzig, the Luftwaffe fighters encounter the markers at Leuna first. Again, they shoot a bomber down- this time a Lancaster, but it’s too late.

While the night fighters are busy 30km away, the bomber stream strikes Bohlen. 211 Lancasters hit the refinery over the course of eleven minutes. Realising their mistake, the Luftwaffe arrive at 0410 as the last bombs are falling and give chase, but their efforts are disrupted by specialist jamming aircraft spread throughout the bomber stream degrading their radar and radio systems.

Despite this, five more RAF bombers are shot down before they return to safety over France, against which the RAF’s Mosquitos managed to claim another German night fighter.

Meanwhile…

But we’re not done yet. Bohlen is only one of two Bomber Command targets this night.

At 0417, 27 Mosquitos arrive over Bremen, way to the north, attracting the local night fighter force, while another 211 bombers start to climb from their low level flight over the North Sea. With the Luftwaffe’s attention focused on Bremen, they escape without notice until after they’ve hit another refinery at Hemmingstedt, on the German-Danish border.

It takes 16 minutes for this second bomber stream to unload on Hemmingstedt. By the time German ground controllers were classifying their new radar contact as a “weak formation”, the RAF were already turning for home. That said, one Lancaster was shot down near Hemmingstedt by a Luftwaffe night fighter in the right place at the right time.

Both the targets for the night were successfully struck thanks to a combination of deception, electronic warfare and mass.

Conclusion

There is something of a caricature of WW2 strategic bombing being a blunt instrument, with RAF or USAAF aircraft simply flying to cities and carpet bombing them. Like all caricatures that’s not entirely wrong, but there is significantly more to it, especially in the less visible world of planning and electronic warfare.

Hopefully this has demonstrated the level of complexity in Bomber Command’s operations by the end of World War 2 and some of the elements going into successful bombing missions.

And this is not some kind of especially complex raid. This is the kind of thing that Bomber Command pulls off several times a week.

It’s also worth emphasising that this doesn’t make the Luftwaffe or that night’s controller Rüppel incompetent, stupid or easily fooled. The German air defence system was a good system. Earlier it the war it was very effective, there was a constant back and forth of development and countermeasure across all kinds of areas, from the purely technical to the organisational.

But by 1945, the Luftwaffe simply didn’t have the resources to keep up. Bomber Command had the mass of aircraft, aircrews, fuel and munitions to stage raids with hundreds of aircraft on a routine basis. That made it possible to stretch the German defences thin, maintain constant pressure and carry out the kind of complex, multi-part deception plans characterising the Bohlen Raid. Combined with a technological edge in electronic warfare, Bomber Command could operate over Germany with a degree of confidence in its ability to strike targets without sustaining heavy losses.

So, that’s a closer look at a fully developed Bomber Command mission from WW2. Hope you all found that interesting, if you’d like to watch these videos early and support the channel you can do so via Patreon and Youtube Memberships. Whether you do or not, thanks for watching and I’ll catch you in the next one.