View Full Version : The Bombing of Coventry, 14 November 1940

14-11-2009, 18:20
On this day, the sixty nine years ago, the city of Coventry was bombed almost to destruction.

This posting is a spin off from The "Winston Churchill" thread where the Coventry raid was mentioned. It deals mainly with the lead up to the raid from the Intelligence and technical viewpoint.
On the night of 8.Nov.1940, the anniversary of Hitler’s Munich Beer Hall Putsch of 1923 (an attempt to overthrow the Weimar government and the ‘birth’ of the Nazi party), the RAF launched a large raid and bombed Munich. This rather spoiled Hitler’s annual festival and upset him so much that he vowed to avenge it. The result was the devastating raid on Coventry in an operation codenamed "Moonlight Sonata".
The German Night Navigation System
Bombing accurately by night was a problem for both sides, but the Germans were far advanced in the development of their Knickerbein, X-Gerat and Y-Great radio navigation systems. For Coventry only the X-Gerat system was used.

The X-Gerat Beams
A beam is a merely a radio signal transmitted from a directional aerial. The German navigation beams were based on the Lorenz blind landing system and consisted of two such transmissions from side by side aerials, linked mechanically on a turntable. The transmitters were oriented so that the two beams were slightly diverging such that there was an area of overlap between the transmissions where both signals could be received simultaneously. The left signal transmitted dots and the right one dashes. They were synchronised so that the time interval between the dashes was exactly the same as the length of a dot. When one was exactly halfway between the signals they were received in equal strength and the dashes merged with the dots to form a continuous note. If one were too far to the left of this point the dots would be louder, or if too far to the right the dashes would be louder. This area of continuous signal was extremely narrow (10 seconds of arc or 20 yards at 200 miles) so one could fly very accurately along this line maintaining a very accurate course.

But this would only give an accurate bearing. In order to locate a target along this bearing an intersecting or cross beam of the same type was used. In fact the X-Gerat used three crossing beams.

The director beam, transmitted from Cherbourg, was laid directly over the target. The aircraft would locate and fly along this beam to the target. Three cross beams, from the Calais area, intersected the main beam at distances of 5, 20 and 50 kilometres from the target. The 50 km beam (the advance beam) gave advance warning (to wake up the crew?) of the approaching next 20 km beam (the fore beam). The fore beam told the navigator to start a small mechanical computer which was stopped as they crossed the 5km beam (the main beam). This calculated the actual ground speed of the aircraft which together with the altitude (entered by the navigator) gave a very accurate bomb release point.

The Countermeasures
The beams could be jammed but that would alert the Germans straight away, so a more subtle method was used instead. To counteract the accuracy of the beams, special mobile transmitters (codename "Bromide") were used. They were positioned along the beams and transmitted dashes on the same frequency as the beam. This made the navigators think they were too far to the right and thus the aircraft would compensate by flying to the left off the beam.

The Bromide dashes were not synchronized with the dashes of the beam, so merely confused the navigator. Had they been synchronized the beams could effectively been "bent". This gave rise to the legend of bending the beams, which was not the case.

These countermeasures were generally successful, spectacularly so in a couple of cases where pilots landed their aircraft in England convinced they were in France!

The Intelligence Side
Bletchley Park was alerted to give priority to Luftwaffe signals to and from Kampf Gruppe 100 (KGr100), which was their Pathfinder or Target Locater group. From these signals the frequency and bearing of the beams and thus their intended targets could be learned. These signals were not usually sent out until the afternoon of the raid, so it is no surprise, and to their great credit that as many as one in three were decoded in time for the countermeasures to be put in place.

The person with direct night to night responsibility for identifying the intended targets and instigating the countermeasures was Professor R.V.Jones of the Scientific Intelligence Service.

The X-Gerat stations had become so adept at setting and resetting their transmitters that, by early November 1940, they enabled KGr100 to mount two raids in succession in one night. On the 10th November 1940 Prof. Jones received from Bletchley Park an intercepted signal to the X-Gerat stations that indicated, for the first time, to prepare settings for three targets, numbered 51, 52 and 53 (targets were never named), which turned out to be Wolverhampton, Birmingham and Coventry. Unusually, only course settings were specified which were insufficient for accurate bombing.

On the 11th November another signal was received, indicating a major operation codename "Moonlight Sonata" which was to be a heavy attack scheduled for the next full moon on the night of 14th November. Also on the 11th another signal indicated raids on targets 34 and 39 which were Liverpool and Coventry (different from 53). Different numbers were used to differentiate between targets in the same location and were often changed. Both these targets were bombed on the 12th November.

On the afternoon of the 14th Nov the signals to the X-Gerat stations could not be decoded in time. Thus neither the intended targets nor the frequency of the beams were known. Other intelligence reports suggested London was to be the target of ‘Moonlight Sonata’. So at about 5.30 pm, educated guesses were made for the location and frequency with which to set the Bromides.

At 6.00pm all that was known was that a heavy attack was due. But on which target, or targets, was not known.

That afternoon Churchill had set out from London with the intention of spending the night at Ditchley Park (a retreat from Chequers near Oxford) which he used on moonlit nights. On the journey he was reading the daily Enigma decodes which indicated a heavy raid was due and listed London as one of the possible targets. Thinking it might be on London, he immediately ordered the car to return. To his great credit he always insisted, when possible, on staying the night in London if an air raid was expected there, and went to the Air Ministry roof to watch the expected air raid.
The Raid
KGr100 crossed the south coast of England at about 6.30 pm. and joined the director beam soon afterwards. At about 7.20pm they arrived at their target of Coventry and dropped parachute flares and phosphorus incendiaries to start fires. These acted as target markers for the following 500 bombers of Luftflotte 2 and Luftflotte 3 to aim at. They dropped more incendiaries, large 500Kg bombs and 1000 Kg landmines.

Some of the targets were industrial areas but the majority fell on the city centre. The bombers followed relentlessly wave after wave and bombed continually from 7.30pm. until about 6.15am. the next day.

Over 200 fires were started which grew and merged into an enormous firestorm which could be seen 150 miles away by approaching bombers as they crossed the southern coast of England. The fire services were powerless to prevent it, they were simply overwhelmed as many of the water mains had been destroyed.

By 2.00 am. The anti aircraft batteries had run out of ammunition.
The Toll
There were 4,330 homes destroyed and three-quarters of the city's factories damaged. Amongst the rubble lay human remains some of whom were never identified; 554 men, women and children lay dead and 865 seriously injured.

There were 624 shops destroyed; 111 out of 180 factories damaged, 75 of them destroyed; 28 hotels, 80 garages & 121 offices destroyed. The city's tram system was destroyed and never ran again. Out of a fleet of 181 buses only 73 remained. Practically all gas and water pipes were smashed and people were advised to boil emergency supplies of water.

It was perhaps a miracle that the figures were not higher considering the city had been hit by 30,000 incendiaries, 500 tons of high explosive, 50 landmines and 20 oil-mines, non-stop for eleven long hours.

King George VI visited and toured the devastation on the 16 November. On 20 November the first mass burial took place at the London Road Cemetery. Bodies continued to be uncovered amongst the destruction of the city and the following week a second mass burial took place.

Although higher total casualties had been seen in London, the relatively smaller population in Coventry meant that each person had actually stood a 60% higher risk of being killed in Coventry that night, than the average anywhere else in the UK during the war.

So why did the countermeasures appear not to work? Post raid analysis showed that the Bromides had been set to the correct frequency but unfortunately the modulating frequency (the audible tone of the dashes) was incorrectly set. It was set to 1,500Hz instead of the 2,000Hz that the aircraft’s X-Great receivers were set. The receiver’s filters made the 1,500Hz tone inaudible to the operator and thus the Bromides had no effect. This error has never been satisfactorily explained.

It now became apparent why the X-Great stations received only course direction settings. Area bombing did not require a fine setting, it was more effective with the course setting, giving a target area of about half a square mile – just right for a medium sized city centre.

The world had never previously witnessed this sort of airborne destruction before and the Germans coined a new word for it 'Coventrated’.

Although Coventry was not the heaviest raid and not the only city to be attacked during the war, it together with the London Blitz is the most remembered. This was the first time an attempt had been made to destroy a city instead of just military and industrial targets.

Perhaps it was because it was the first, or because of the destruction of the 600 years old St. Michael’s Cathedral, or perhaps the ruthlessness in which it was carried out, but somehow this seemed to affect the British people. It somehow seemed a personal attack. After that the gloves came off, so to speak, and sparked a deep desire to avenge it. They wanted the Germans to be given a taste of their own medicine. As Air Chief Marshall Sir Arthur Harris, CinC Bomber Command, said of another occasion, "They sowed the wind and now they are going to reap the whirlwind".

Coventry showed Bomber Command how a firestorm could be started and developed techniques to make it happen. Coventry removed inhibitions about bombing cities and civilians.

Coventry will always be remembered.

14-11-2009, 18:45

Thanks for the very interesting and informative piece.

I have read that, through enigma, we did know the target and Churchill was heavily criticised for refusing to add additional AA defences around Coventry, to prevent the Germans having any suspicions that their communications were being intercepted and decoded. I am not sure where I read that.

14-11-2009, 19:03
Dave, It is one of those myths which won't go away. It has been refuted by everyone present and with direct knowledge and direct experience of the situation at the time. But as with all conspircy theories there are those that still choose to believe it despite all evidence to the contrary, and continue to perpetuate it.

If the department and personnel directly responsible for predicting the target did not know, even at the late hour of 6.00pm, how on earth was Churchill supposed to know beforehand? He actually thought London was to be the target. Everyone was reduced to guessing because the signals could not be decoded that day.

14-11-2009, 19:05
A very interesting account of the raid on Coventry. Thanks for posting it.

14-11-2009, 19:41
In my haste to get the posting completed for today I forgot to post these with it.

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14-11-2009, 21:13
I have done a little reserch on how the Churchill myth started and come up with this from Wikipaedia.

Coventry and Ultra
In his 1974 book "The Ultra Secret", Group Captain F.W.Winterbottom asserted that the British government had, from Ultra, advance warning of the attack. He further claimed that Churchill ordered that no defensive measures should be taken to protect Coventry, lest the Germans suspect that their cipher had been broken. Winterbotham was a key figure for Ultra; he supervised the "Special Liaison Officers" who delivered Ultra material to field commanders.

However, Winterbotham's claim has been rejected by other Ultra participants and historians who argue that while Churchill was indeed aware that a major bombing raid would take place, no one knew what the target would be.

Peter Calvocoressi was head of the Air Section at Bletchley Park, which translated and analysed all deciphered Luftwaffe messages. He wrote "Ultra never mentioned Coventry... Churchill, so far from pondering whether to save Coventry or safeguard Ultra, was under the impression that the raid was to be on London."

Scientist R.V.Jones, who led the British side in the Battle of the Beams, wrote that "Enigma signals to the X-beam stations were not broken in time," and that he was unaware that Coventry was the intended target. Furthermore, he explained that a technical mistake caused jamming countermeasures to be ineffective.

Winterbottom had a supervisory role and was not directly involved with the detail of each signal. While he had a general knowledge of the many external departments he dealt with, he could not possibly follow the thread and detail on a day to day basis of every signal he passed over. There was just too much information. Only the receiving department could do that. And they refute his allegations.

His book was written over thirty years after the event. He must have been writing from memory as everything was destroyed, even the computers, to preserve the secret. He may simply have been confusing it with other events. After all he was nearly 80 years old when he wrote the book.

Even so he did Churchill a great disservice, whom, had he still been alive when the book was published, would surely have sued for libel. But dead men can't sue.

14-11-2009, 21:58
How The Times reported the bombing of Coventry

15-11-2009, 03:01
I dont know if anybody saw it or not but there was a really good documentary about the Bombing of Coventry that was shown about a fortnight ago ??

It was a brand new documentary as it had copyright 2009 in the credits and was entitled:

"Blitz:The bombing of Coventry". It was aired on October 6th BBC2 at 9pm.

I thought it was really first class with excellent footage and eye-witness accounts. Well worth seeing if you get the chance.

15-11-2009, 03:10
...And as it happens you lucky people do have the chance to see this brilliant documentary!!



15-11-2009, 03:58
Thanks for posting the documentary, Terry

Unfortunately it is for "U.K. Eyes Only"


15-11-2009, 04:10
I realise that Dave but at least those of us still suffering life in the UK will have the option! ;)

15-11-2009, 17:15
I must admit I thought this information would result in some sort of response. Obviously members are not interested - unless I have been sent to Coventry?

15-11-2009, 18:10
Yes Terry I saw it too about a week ago, and also found it fascinating.

I always find personal stories of battles interesting, they add a different dimension to them. That is why I enjoyed reading Spike Milligan's books of his time in the Army. His view of battle was "we were ordered to set up the guns at this location; aim them at somewhere else and fire until told to stop. We then packed up and moved to somewhere else and did the same thing again. I never saw what we were aiming at, or where the rounds landed, or why we were firing this target. Sometimes we were told what the target was", or words to that effect. As I said, a different view of battle.

I digress, the Coventry program is being repeated tonight at 03.50 on BBC1.

John Odom
15-11-2009, 18:20
Unfortunately, The BBC website linked above says the video is not available to internet users outside of the UK.

16-11-2009, 14:58
Thanks Bill - I too thought it was a very good programme and hope that other members manged to see it.

Regarding the point made by both Dave and John it is a great shame that those living outside of the UK are unable to watch the programmes on BBC I-player. No doubt that there is some half-baked reason why this is the case but a shame nevertheless...

16-11-2009, 15:52
I think that it is all about money (as usual)

The BBC wants to sell the programme or series abroad and make money and not give it away free.

Here we have BBC America, American History Channel, History Channel International and the P.B.S. (Public Broadcasting Service). All of them show these types of programmes.

David Verghese
22-11-2009, 19:59

Thank you for your detailed description of the bombing of Coventry on 14 November 1940. I particularly liked the way you portrayed the information broken down by key aspect.

Terry – I, for one, do appreciate your listing of the BBC i-player link and I did watch it as a result of your posting earlier in this thread, having missed the original TV programme on October 6. Thank you.

My interest in this thread has a personal bearing in that I was born in the city of Coventry of 1946 vintage – my lifelong armchair support of Coventry RUFC being testament to that, as well as an active support of Warwickshire CCC, helped by the fact that we moved to nearby Birmingham when I was one year old; I digress, and therefore back to the thread.

By late 1940 one would have expected that Coventry (Koventry on German maps, the significance of which appears further on) with its large number of engineering, military vehicle and ordnance factories would have been a strategic target for German bomber raids. Indeed names resplendent of Coventry’s industrial heritage at the time included Alvis, Triumph, Singer, Humber, Standard, Armstrong-Whitworth to list just some. Many of these manufacturing sites were situated away from the centre of the city which itself contained much architecture of medieval interest. Coventry had been bombed earlier that year – but without the subsequent attendant use of booby-trapped incendiaries, phosphorous bombs, parachuted landmines and oil mines, all of which contributed to the concentrated and horrific toll on the civilian population and central area of the city on that night. The fire fighting service fought valiantly in the face of hopeless odds and lost many to fatalities and serious injury in facing openly the consequences of such dangerous ordnance.

The myth that Coventry was sacrificed by Churchill to save exposure of the breaking of Enigma has endured over the years, a grave disingenuous legacy in the face of many historians demonstrating its fallacy after careful analysis of known facts. Besides the book by Group Captain Winterbottom to which Bill(emason) alluded , other books in the seventies, notably “Body of Lies” by A.Cave-Brown and “A Man called Intrepid” by William Stevenson also contributed to the conspiracy theory concerning Coventry.

The codebreakers of Hut 6 at Bletchley Park (well worth a visit by the way) had succeeded in getting key information about potential air targets via the Red code(changed nightly). A forthcoming raid on Birmingham was indicated by the use of the word Bild, a covername for Liverpool was Liebe, and that for Wolverhampton was apparently indicated by an oblique reference to Woolies sales slogan of the time!

To add to Bill’s analysis of that night endured in Coventry I feel that the text below quoted directly from a book entitled “STATION X the Codebreakers of Bletchley Park” by Michael Smith (Publ. By Channel 4 to whom Copyright is duly acknowledged) clarifies further the factual history. The author was a former member of the Intelligence Corps. The term ‘Brown cypher’ below refers to the Luftwaffe key whose code was broken by Hut 6 about nine weeks earlier.

“The earliest signs of an unusually large raid came in a decrypt on the Brown cipher revealing that the beams were to be used for an operation which the Germans codenamed ‘Moonlight Sonata’, because it was to coincide with a full moon. It gave no further information other than providing a list of four possible targets, all in London and the Home Counties, leading air intelligence to conclude that the target was once again London. Evidence obtained from a captured Luftwaffe pilot gave warning of a major raid due to take place at a full moon; the interrogation report said the raid was codenamed ‘Moonshine Serenade’ and was aimed against Coventry and Birmingham. The Air Ministry dismissed this information, preferring to believe its own analysis of the German Message. It also disregarded navigational beams aimed at the West Midlands, assuming that they were part of German trials of the equipment which had been going on for some time.
It was only later that anyone realised that the use of the previously unknown codeword Korn, the German word for corn, in the initial message was in fact the covername for Coventry, which the Germans spelt with a K. While with hindsight the Air Ministry’s dismissal of Coventry as a potential target is evidence of the poor coordination of intelligence within Whitehall at the time, it was certainly not ignored to protect the codebreakers’ secret.”

Between the years 1658 to 2001, six ships of The Fleet have borne proudly the name HMS Coventry. The seventh is awaited.


23-11-2009, 16:02
Thanks David - your comment was greatly appreciated.

To me it makes it well worthwhile if just one person benefitted from knowing about it. :)

David Verghese
25-11-2009, 15:08
Having watched the i-Player recording of the bombing of Coventry a couple of times I began to think of how and when such similar episodes of war are remembered in other countries by those whose forebears suffered. Hamburg and Dresden at first spring to mind but, with one of my interests being the German-Russian war, the Eastern Front of 1941-45, it did not take long to come across this unusual but compelling art form commemorating the bombing(s) of Kiev in the Ukraine in 1941.

I did hesitate for several days before submitting the u-tube link below, regarding relevance to the Forum. There is a small naval element to the 9-minute clip near the very end where a Ukranian 'navy soldier' is portrayed, I think saying goodbye to his family as he is called to arms for his country.

On the method side, the table is covered in sand and is lit from beneath. An overhead camera projects her very skilfull portrayal onto a screen.


The effect on the audience, whose country lost up to 25% of its population in WWII, is self apparent.

The submission won the competition "Ukraine's got Talent"


14-11-2010, 18:00
Today is the 70th anniversary of the Bombing of Coventry. At the time of posting this, the first German aircraft would be approaching the south coast of England.