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Coventry and Enigma: Did Churchill sacrifice the city?

It is one of the most persistent stories of the Second World War. Churchill is said to have known in advance that the Luftwaffe would attack Coventry on the night of 15 November 1940. He is said to have neither warned nor evacuated the city, so that the Germans would not notice that the British were reading their radio traffic. The price would have been hundreds of dead, the gain a secret called Ultra. The question is old, and it is uncomfortable. This page looks at what speaks for it, what speaks against it and where the story comes from in the first place.

I. The night of Coventry

The raid on the night of 14 to 15 November 1940 bore the code name "Moonlight Sonata". The name betrays a condition: the bombers needed a bright moonlit night. Coventry was a centre of the British aero-engine industry. The raid belongs to the phase of the night-time bombing war against England that the British call the "Blitz". You will find the context on the page Battle of Britain.

The destruction was severe. The old town burned, and the medieval cathedral was destroyed. Afterwards the National Socialists coined the word "coventrieren" ("to coventrate") for the complete destruction of a city.

The figures vary depending on the source. According to the Imperial War Museum, 568 people died; the page Air War gives the figure 554. The number of bombers deployed is put at between 449 and over 500 aircraft. Another source considers up to 1,000 dead possible, because many workers who had moved there were never recorded. That is a reason for caution whenever a very precise figure is given somewhere.

II. What Enigma and Ultra achieved

Enigma was the cipher machine with which the German Wehrmacht, including the Luftwaffe, encrypted its radio messages. The Polish mathematician Marian Rejewski had already broken into the code at the beginning of 1933. In July 1939 the Poles passed on their knowledge to the French and the British at a secret meeting. From January 1940, a large part of the German radio traffic was read at Bletchley Park, north-west of London; only naval radio traffic initially held out. The British called the result "Ultra". More on this can be found on the page Air War.

The important point is this: Ultra delivered fragments, not a live view into the German command. They had to be interpreted, and they were not always unambiguous. This is where the Coventry question is decided.

III. The legend and its origin

It was not until 1974 that the book "The Ultra Secret" by Group Captain F. W. Winterbotham appeared. During the war he had headed the "Special Liaison Officers" who delivered Ultra material to the commanders. He claimed that the government had been warned of the raid in advance through Ultra. Churchill, he said, had ordered that no protective measures be taken for Coventry, so that the Germans would not notice that their encryption had been cracked.

The story became popular. It has a great name at its centre, and it raises a genuine moral question. There is even a play about it: "One Night in November" by Alan Pollock. It tells of a member of staff at Bletchley Park who stands between truth and silence.

IV. What the sources say

Historical research takes a largely critical view of Winterbotham's account. The most important objections:

  • The documents do not support the story. According to Norman Evans of the British Public Records Office, the decrypted radio messages of the days before 14 November did announce a major raid on an English city. But Coventry was never named in them. The target was rather suspected to be in the south.
  • Winterbotham wrote from memory. A historian questioned by the newspaper said the book was not particularly accurate in this respect. That it was known Coventry was the target is not supported by the files.
  • There was a warning, but without a target. On the afternoon of 14 November, Churchill drove to Ditchley, where he spent moonlit nights instead of at Chequers. On the way he opened his Ultra box and learned that the heaviest raid so far was imminent. But the target was still open.
  • The target was evidently identified in a different way. According to the account of John Colville, who was close to Churchill, the information about the location did not come from Ultra. The target was only recognised when the German radio guidance beams crossed over Coventry. This fits with what the page Air War says about the Knickebein method: the bombers fly along one guidance beam, and a second beam shows them the target.

The historian Frederick Taylor devoted an entire book to that night ("Coventry: Thursday 14 November 1940") and examined the rumour in it. His opinion: the British government could not have known beforehand that Coventry would be hit.

V. A word on the version on this website

The page Air War presents the Winterbotham version as a narrative: Bletchley Park is said to have decrypted a radio message at 3 p.m., and Churchill is said to have refused the evacuation. There is also a note there that the current state of research doubts this and that the story is mentioned as a thought experiment. That is the right way to classify it. This article goes deeper: it was a thought experiment, not a documented event.

VI. Why the story still holds up

  • It is simple. One man, one secret, one city, one decision.
  • It is not entirely made up. The British really were reading along, and they had every reason to protect Ultra. And a major raid really was in the offing.
  • It seems to explain things. Anyone who believes that "those at the top" knew everything does not have to come to terms with the disorder of reality: with gaps, errors, wrong interpretations.

The question behind it remains genuine: may a secret be placed above human lives if the outcome of a war may depend on it? That is a question for a seminar or a column. For Coventry in November 1940, according to current knowledge, it does not need to be answered.

VII. Conclusion

The story of the "sacrificed" Coventry essentially goes back to a book from 1974 that was written from memory. The surviving files do not support it. They show a British leadership that expected a heavy raid but did not know where it would go. That is less spectacular, but closer to what intelligence work actually is: a puzzle in which the decisive pieces are often missing.

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