Unravelling Enigma

Maurice Freedman

• Editorial: Pen & Sword Military
• Año: 2001
• ISBN:
  9781473820159
• Categoría: Geschichte
• Categoría: Zweiter Weltkrieg

Seldom out of the news for long, code-breaking has had a bad time in the media so far, readers and viewers often finding it as perplexing as it is intriguing. As one of the greatest achievements of the century, code- breaking is a fascinating story, but all too often misunderstood and felt to be obscure. The author covers the story from the early code-breaking efforts through the rickety structure of the pre-war Government Code and Cypher School to Bletchley Park where a large powerful organisation arose, unscrambling thousands of secret enemy messages every day. Detailing how these amazing discoveries were actually used, taking us briefly into some of the battles of the Second World War, and in some detail the Battle of the Atlantic, when Britain was in danger of starving and where the war was nearly lost.For the first time, the code-breaking story with all its complexities is told in a straightforward and readable manner, whilst at the same time it will not fail to intrigue and astonish readers.

CONTENTS

Acknowledgements
Introduction
1	‘Gentlemen Do Not Read Each Other’s Mail’
2	The Polish Enigma
3	The Impossible We Do Immediately … Success and Expansion at Bletchley Park
4	Hut Six – Where It All Began
5	Guessing with Virtual Certainty The Turing-Welchman Bombe
6	Hut Three – Getting to Know the Enemy
7	Huts Four and Eight – Searching for U-Boats
8	How Not to Keep a Secret
9	Greece and Crete – The Code-Breakers Lend a Hand
10	North Africa – Ultra Triumphant
11	The Atlantic – Where the War Was Nearly Lost!
12	Defeat for the U-Boats
13	Colossus and Tunny – The Big Fish … Miracles Take a Little Longer
14	1944 – The Invasion of Europe Allied Deception Plans
Tailpiece
Appendix 1 – The Codewheel
Appendix 2 – Operating the Enigma Machine (Military and Air Force) from 15 September 1938 until May 1940
Appendix 3 – Setting up the Naval Enigma Machine
Appendix 4 – Bletchley in Danger
Appendix 5 – Enigma and SZ 40/42 (Tunny)
Bibliography
Index

ACKNOWLEDGEMENTS

My thanks are due, in the first instance, to Nora Millward, without whose generous loan of several volumes of the Official History, British Intelligence in the Second World War, I might not have started. Ralph Parker, one of the stalwarts of Hut Six, was kind enough to read the script at an early stage, and generously gave me a splendid picture of Hut Six staff celebrating Victory in Europe Day, 8 May 1945. Peter Calvocoressi gave friendly encouragement. Peter Coast cast a mathematical eye over some of the more technical passages. I owe a good deal to my lecture audiences, some of whom were personally involved in code-breaking or allied activities and whose searching questions, as well as helpful suggestions, have helped to keep me on the right track.

The following authors and publishers have given permission to quote extracts from their publications:

Antony Beevor, Crete – The Battle and the Resistance (John Murray (Publishers) Ltd, 1993).

Ralph Bennett, Ultra in the West: The Normandy Campaign of 1944–45 (Hutchinson, 1979).

Ralph Bennett, Ultra and Mediterranean Strategy, 1941–45 (Hamish Hamilton, 1989).

Peter Calvocoressi, Top Secret Ultra (Cassell, 1980).

F.H. Hinsley et al., British Intelligence in the Second World War, Official History. Crown Copyright is reproduced with the permission of the Controller of Her Majesty’s Stationery Office. F.H. Hinsley and Alan Stripp (eds), Codebreakers: The Inside Story of Bletchley Park (1993). Reprinted by permission of Oxford University Press.

Andrew Hodges, Alan Turing: The Enigma (Vintage, 1992).

David Kahn, Seizing the Enigma (Souvenir Press, 1992).

Christopher Morris, Navy Ultra’s Poor Relations, from Intelligence and National Security, Vol. 1, No. 1 (1986) (Frank Cass & Co. Ltd).

The Oxford Companion to the Second World War (1995). Reprinted by permission of Oxford University Press.

Gordon Welchman, The Hut Six Story (Baldwin, 1997).

Picture credits: pictures 1–7, Bletchley Park Trust/Science and Society Picture Library.

Jacket Illustration, Bletchley Park Trust/Science and Society Picture Library.

The King hath note of all that they intend,
By interception which they dream not of.

Henry V (Act II, Scene II)

INTRODUCTION

If the astonishing code-breaking carried out at Bletchley Park during the Second World War was truly ‘Britain’s greatest twentieth-century achievement’, and helped to shorten the War, it deserves better treatment in print and in the media than it has so far received.

To those who have been confused, indeed perplexed, by what they have already read or seen of code-breaking, as well as those coming new to this topic, I offer a straightforward, readable account, where the reader may follow the story without being discouraged by mathematics and technology. I have tried to keep necessary explanations as clear as possible, and avoid the jargon which so often plagues this subject. I have also sketched in some of the wartime background against which these events took place, and have looked at the role played by Ultra intelligence (the secret information obtained by code- and cipher-breaking) in some of the great land battles of the War, as well as examining its part in the Battle of the Atlantic.

British code- and cipher-breaking attained a huge success in the Second World War, when, for the first time in history, one side was consistently listening, on a very large scale, to the secret military intelligence of the other.

The essence of that achievement was the sheer scale of the operation. Whereas the Poles had determinedly broken the German Enigma ciphering system from 1933–8, although without obtaining much information, the British created, out of a chaotic intelligence situation, one big organization capable of deciphering and processing thousands of secret enemy signals every day, turning them into valuable information, often vital for the conduct of the War. Complex and difficult as these processes undoubtedly were, they were accomplished with assembly-line precision and in industrial production quantities.

The British learned to know their enemy as well, and sometimes better, than he knew himself. It was said that if, in 1944, you wanted to find three people who knew more about the German Air Force than anyone else, they would be found, not in Germany, but at Bletchley Park!

For a country which, at Dunkirk, had suffered a most humiliating retreat, and seemed in 1940 almost certain to lose the War, possession of this ‘secret weapon’ proved, by 1944, when the Allied invasion of Europe took place, to be of supreme value.

The story of code- and cipher-breaking and the Ultra top secret intelligence it produced, has been bedevilled by two factors. First, Bletchley Park, in wartime, operated a very stringent ‘need to know’ rule – ‘if it’s not your job, don’t ask’ – and a tight division of labour, so that perhaps fifty or sixty out of 7,000 people had an overall, although not a detailed, picture of the work.

Then there was a time-lag of some thirty-three years before the secrecy restrictions were lifted – and then not completely – in 1978, and officially, at least, no private written records of this secret wartime activity should have been kept.

The combined effect of the ‘need to know’ – what one Bletchley veteran called, ‘the tunnel vision from which we all suffer’ – and the fading memories, became evident when the ban was lifted in 1978. Books and articles appeared, some of which were wide of the mark, spreading misinformation and confusion, especially as information emerged in piecemeal fashion. Most aspects of the Second World War have a generally agreed history, but owing to the long official silence, the code-breaking story was far from clear. Then the authorized History of British Intelligence in the Second World War began to appear (five vols; 1979–90) and things started to improve, but by then a good deal of damage had been done. A lot of misinformation still persists; indeed, it is difficult to read a newspaper article, a reference book or an obituary notice without being aware of the errors still in circulation. Nor was the television series about Bletchley Park of much help, leaving many of its viewers more confused than enlightened. Leaving aside its inaccuracies, what I found particularly irksome was the absence of any recognition of Gordon Welchman, without whom Bletchley Park, as we know it, would not have existed. Very early in the War Welchman saw that it was not a matter of breaking a few secret enemy codes, but in order to make a real impact on the outcome of the War Bletchley would have to decode or decipher hundreds and probably thousands, of messages every single day. Accordingly, he planned a large, round-the-clock, code-breaking organization, and persuaded his bosses to take immediate action. Had they not done so they would not have survived.

Welchman’s second great contribution was to develop Turing’s experimental ‘Bombe’ – a machine to help in large-scale deciphering – by a modification so dramatic that it could then cope with increased numbers and with a greatly reduced margin of error, so that, in the words of Turing’s biographer, ‘the Bombe would enjoy an almost uncanny elegance and power’. This quite serious omission may be no more than another example of the now common media attitude, ‘why let the facts spoil a good story?’

An early source of misinformation had been Group Captain Winterbotham, a senior wartime Secret Service officer, who had obtained permission to publish as early as 1974, and whose book, The Ultra Secret, first in the field and widely read, contained a variety of misleading and even sensational statements. The story, which I encountered several times when lecturing on ‘Ultra’ subjects, that Churchill allowed Coventry to be bombed in 1940 because defending it would have revealed to the enemy that their messages were being deciphered, comes from this book, and is without foundation. Typical of Winterbotham’s attitude is his whimsical, and quite unforgivable, description of the Bletchley Park ‘Bombe’ as being, ‘like some Eastern Goddess who was destined to become the oracle of Bletchley’. As he should have known, this ‘oracle’ only gave the correct answer when fed with very accurate estimates of part of what the original – but still enciphered – enemy message contained! This was a mind-boggling, nerve-racking task to try the skill, brains and patience of Bletchley’s saints and geniuses, the agony being compounded by having to start afresh each day, as the enemy changed his ciphering arrangements at midnight! I am reminded of the American music devotee who gushed, ‘Oh, Mr Heifetz, your violin sounds so wonderful!’ ‘Oh,’ said Heifetz, looking at the instrument in his hands, ‘I don’t hear anything!’

Terminology

I have used the term code-making to describe preparing a communication between two parties which is to be kept secret, and code-breaking when an unauthorized third party decodes or ‘breaks’ the secret code.

In this book we are concerned mainly with ciphers in which individual letters are disguised, and here I have preferred encipher and decipher, rather than encrypt and decrypt (or worse, encryption and decryption), now in common use, but not current during the War, and which come from the US. Similarly, I have avoided cryptographer for one who prepares a code or cipher, and cryptanalyst for one who breaks codes and ciphers.

During the War the word ‘decoding’ was in common use, regardless of whether codes or ciphers were broken, the successful results called ‘decodes’, and this will appear where appropriate.

‘Speed of attack through speed
of communications’

The German military theory of ‘blitzkrieg’, of lightning war, was designed for an aggressive country that was not rich in resources, and as the First World War had shown, could not survive a prolonged conflict. The aim was to overwhelm its victims with highly mobile armoured divisions, motorized infantry, self-propelled guns, all preceded by squadrons of dive-bombers spreading destruction and terror ahead of the advancing armies, and these methods took first Poland, then Western Europe, by surprise in 1939/40. Combined operations on this scale demand a very high degree of co-ordination, and that, in turn, requires swift and reliable communication. In the 1930s the Germans would hold conferences in which these blitzkrieg tactics were openly proclaimed, the aim being to intimidate their neighbours.

At one of these conferences Sir William Stephenson, a wireless expert, asked how their air force would get ground support so far ahead of the army. The Air Minister, General Erhard Milch, replied,

The dive-bombers will ...

Índice

• Cover
• Half Title
• Full Title
• Copyright Page
• Dedication
• Contents