John Jackson




Hitler’s Codebreakers: German Signals Intelligence in World War 2 Edited by John Jackson

Published by BookTower Publishing April 2013 ISBN 978 0 9557163 4 7

To buy the print version of from Amazon uk and here. Ebook versions are also available.

The wartime story of codebreaking has almost exclusively centred around Allied successes, particularly that of Bletchley Park. However, the Germans in particular were extremely active in codebreaking and had their successes. But it was not until after the war that the extent or otherwise of their triumphs could be gauged. With the war in Europe at an end, in April-May 1945 British and American codebreaking teams hunted for their German counterparts to find out just how good they had been. There were lessons to be learned for the post-war period for Western intelligence.

This publication is based on European Axis Signal Intelligence in World War II as revealed by ‘TICOM’ Investigations and by other Prisoner of War Interrogations and Captured Material, Principally German and completed in May 1946. This is available on the National Security Agency website. TICOM – Target Intelligence Committee – was a shadowy Anglo-American organisation set up in October 1944 whose cover name disguised its real purpose – the seeking out in the immediate aftermath of the war of German Sigint staff for interrogation.

This fascinating insight into German cryptography shows how they understood that the Enigma cipher machine had weaknesses and that they had various ingenious machines either developed or under development as the war drew to a close. Lack of resources – and running out of time – put paid to any major operational deployment of this machinery, but underlines the fact that German ingenuity came close to a situation where they would have made Bletchley Park’s task almost impossible.

This book is a shorter edited version of declassified TICOM documents (amounting to approximately 1000 pages) that are available on the NSA’s website. The original documents were prepared by codebreakers and therefore contain technical descriptions.


CODE WARS by John Jackson

Pen & Sword. Published July 2011. ISBN 978 1 84884 510 7

Code Wars studies the effect of intelligence gained through Ultra (British Sigint) on specific operations and how this influenced the outcome of crucial campaigns such as North Africa, Crete, the Normandy invasion, as well as key naval battles, the Coventry-Churchill controversy, the V1 and V2 weapons, Hitler’s invasion of Russia and the US Sigint contribution.  It also examines the development of Colossus to break German High Command messages and became the world’s first computer. The vital role of the intercept stations is highlighted and as a result of these activities the war was probably shortened by as much as two years, leading Signals Intelligence into the new Cold War era.



Bletchley Park Trust Report No. 16Bletchley Park Trust Report No. 16: Breaking Army and Air Force Enigma: German security counter-measures and how Bletchley Park’s Hut 6 overcame them  edited by John Jackson

Published September 2009. ISBN 978 1 906723 09 5.

The booklet examines through original declassified end-of-war Bletchley Park reports, nine particular cryptographic devices introduced by the German cipher authorities to improve the security of the Enigma machine.




NAVAL ENIGMA: THE HISTORY OF HUT 8, 1939 – 1945 by A P Mahon: edited by John Jackson

Military Press. Published 2009

ISBN 978-0-85420-442-7 (Hardback)
ISBN 978-0-85420-443-4 (Softback)

German Naval Enigma messages were the hardest to break at Bletchley Park during World War Two, due to the complicated way in which they were enciphered. A P Mahon, who joined Hut 8 in 1941 and led the naval codebreaking team at for the latter part of the war, gives a unique insight into the methods of discovering the secrets of the Kriegsmarine. These include the year-long battle to overcome the introduction of the four-wheel Enigma machine by the U-boat fleet in February 1942, involving the subsequent blackout of intelligence. The brilliant methods devised at Bletchley Park such as Alan Turing’s Banburismus system, overcoming the double-enciphered Officers-Only (Offizier) and the special U-Boat Short Signals, are all explained. Churchill made clear that the U-Boat war – the Battle of the Atlantic – was his greatest fear during World War Two. This is a unique insight into how that battle for vital intelligence was won, written by someone who was not only part of the team who  helped win that struggle, but also who for part of the time, led it. There is a list of naval keys, a glossary, biography and index.




[Volume 1 (Part2) & Volume 2] by Frank Birch: edited by John Jackson

Military Press. Published 2007

ISBN 978-0-85420-270-6 (Hardback)

ISBN 978-0-085420-771-3 (Softback)

This volume covers 1941 to autumn 1943 and includes Mediterranean, Middle East, India and the Far East, the revision of the Sigint service, shortage of personnel and equipment, expansion of the Y Service, dissatisfaction of GC&CS and its reorganisation, organisational problems at Bletchley Park and the Service ministries, the cryptanalytic and intelligence contribution to the War in the West, ‘Fish’, Army and Air Enigma, German railways, Schützstaffel, Police, Abwehr and German naval systems , Service idiosyncrasies, Battle of the Atlantic and the renascence of anti-Japanese Sigint etc.

Diagrams include the Y organisation, expansion of the Services Branch of GC&CS, staff employed on Bombes, numbers of Bombes delivered, Allied Sigint success against German naval communications, German reading of Allied traffic, the German diagram drawn up to demonstrate why Enigma was impossible to break. 282 pages, 46 pages of diagrams.



THE OFFICIAL HISTORY OF BRITISH SIGNALS INTELLIGENCE 1914-1945 – [Volume 1 (Part 1)] by Frank Birch: edited by John Jackson

Military Press. Published 2004

ISBN 978-0-85420-273-7 (Hardback)
ISBN 978-0-85420-278-2 (Softback)

This Official History was written immediately after the war when the author was the official Sigint historian. In World War One he was a member of the Room 40 team at the Admiralty, and during World War Two he was a senior member of staff at Bletchley Park. He gained a double first whilst at Cambridge University, and after World War One he was a fellow of King’s College, Cambridge. From 1937 he was advising the head of the Government Code & Cypher School (GC&CS). After World War Two he was head of the historical section of GCHQ. He was allowed full access to all records and to ensure accuracy the original manuscript was reviewed by officers of GCHQ. It is the most authoritative account of how the British Signals Intelligence organisation was developed into such a powerful instrument in defeating the Axis.

The History begins with an analysis of the rôle and effectiveness of Sigint in World War One and the aftermath up to the early 1930s. With the increasing threat from Japan, Italy and Germany in the mid 1930s, efforts were made to improve Sigint at home and overseas. With the outbreak of war in 1939 the skeleton of what became the Bletchley Park organisation was in place. There were considerable problems that had to be overcome, not least the competing requirements of the armed services as well as the friction between the UK and overseas commands.

Eventually a unique system arose that involved the armed services, the Foreign Office and an array of civilians, many from the universities. The History includes numerous tables and diagrams that explain the development of the organisation and how it worked, also the inter-connections and the flow of information. For instance ‘The Chain of Control of Interception in 1941’ shows how the Y intercept organisation committee, headed by the Chief of the Secret Service, reported directly to the Chiefs of Staff.
This volume includes First World War and after, the preparations for a new emergency – the pre World War Two organisation. For World War Two it includes the ‘Phoney War’, the Norwegian and French campaigns, plans in the event of invasion, the importance of Y, Military and Air Sigint, organisations in the Mediterranean, Middle East and Far East, naval Sigint in the UK, traffic analysis. There are footnotes and sources and an appreciation of Frank Birch.



ULTRA’S ARCTIC WAR by John Jackson

Military Press. Published 2003

ISBN 978-0-85420-224-9 (Hardback)
ISBN 978-0-85420-229-4 (Softback)

The Arctic convoys that took vital supplies at enormous risk to Russia during the Second World War did so within range of Germany’s Luftwaffe, surface ships and U-Boats. These convoys were watched over by Bletchley Park codebreakers and intelligence officers, through decrypts of the German Enigma cipher machine. In particular, these decrypts were closely involved in three of the key actions of the Arctic battles – the sinking of the battlecruiser Scharnhorst, the destruction of the battleship Tirpitz and the disastrous PQ17 convoy. This book examines the Ultra decodes, and for the first time lists the key details in these events in chronological order, detailing the role of the decrypts in a virtual minute-by-minute breakdown of how the signals were used in these important actions.



THE SECRET WAR OF HUT 3 edited by John Jackson

Military Press. Published 2002

ISBN 978-0-85420-193-8 (Hardback)
ISBN 978-0-85420-114-3 (Softback)

Foreword by Peter Calvocoressi, Head of Air Section at Bletchley Park during the war. At the end of World War II, those who had worked in Hut 3 wrote a history of its activities on German Army and Air Force Enigma. The results were so sensitive that it was immediately given the highest security classification: TOP SECRET ULTRA. This book is based on that publication. Hut 3 was responsible for the processing of the signals once the code in which they had been transmitted had been broken. They translated and annotated them and reported the contents to Government departments and commanders in the field. Churchill received the most important decrypts direct. Hut 3, at its peak of activity, had some 580 men and women working in it, which included 21 Americans. Hut 3 developed into an intelligence organisation the like of which had never been seen before. Their index systems, the technical expertise and research facilities were unique. The book explains how Hut 3 handled the signals they received, and how their processing enhanced the value of the signals. There are chapters on the Military, Air and Naval Sections, also the Duty Officers, Signals Section, the Special Liaison Units, the German Book Room, Hitler’s secret weapons and the arrival of the Americans.



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  1. I have had much joy reading here about things I never knew I knew. This site is of great interest to me as I worked in Tommy Flowers division at Dollis Hill from 1961-69 where I was surrounded by the people who actually created the Colossus machine. From 1969 I worked at the recently established ICL which incorporated Ferranti, Elliot Bros, GEC, Lyons, etc. Some of my colleagues at the Atlas (Manchester Mark 1) installation were from Letchworth who were involved with the Bombes. In fact Manchester University had a considerable input to the Bletchley projects which is not so well known.

    However, in relation to the bombe article, at Dollis Hill there were two divisions, RT and RS linked to Eastcote, where a couple of the Colossus machines ended up. My division, RF, had a lot of dealings with Eastcote since we were developing transistorised telephone switching system. A couple of our maths people, Mike Cole and James Ellis, were working on encryption and Eastcote used our electronic techniques to implement their work.

    It is interesting to compare the intelligence technology these days with that at Bletchley. Hacking into intelligence systems is something children do nowadays. A few years back someone got into the GCHQ hub and published some of it on the internet.He wasn’t a child as he called himself Eastcote Bob. He must have been an old timer like us.