The Ultra Secret: Priceless Value

“The intelligence which has emanated from you before and during this campaign has been of priceless value to me. It has simplified my task as commander enormously. It has saved thousands of British and American lives and, in no small way, contributed to the speed with which the enemy was routed and eventually forced to surrender.” 

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General Eisenhower, Supreme Allied Commander in Europe, wrote these lines on 12 July 1945 in a letter to Major General Sir Stewart Menzies, the Chief of the British Secret Service at the end of the Second World War.  

Bletchley Park and the Ultra organisation were part of his Secret Service. The intelligence which was given to General Eisenhower was called Ultra, and the word itself was secret. 

Ultra was a category of secrecy “beyond most secret”, used to describe intelligence derived from intercepting and breaking the high-level encrypted wireless and teleprinter traffic from the German Enigma and Lorenz cypher machines. 

The codebreakers at Bletchley named the traffic sent via the Lorenz machine as “Tunny”, a fish species. There was a logical reason, but that’s another story. The Italians used a cypher machine called Hagelin to a lesser extent, which also fell under the Ultra umbrella.

Only the select few on the approved Ultra list were allowed to receive this intelligence via special liaison officers. My father was one such SLO, and I told his story in the article, The Ultra Secret: Sensationalist Nonsense.

Enigma and Lorenz were two very different cypher systems and had very little in common. Enigma, with its three wheels, created messages using the twenty-six-letter alphabet. However, the Lorenz SZ40/42 was a much more sophisticated machine with twelve wheels, 501 pins and used a teleprinter code.

The Enigma machines were produced in many hundreds and were deployed throughout the German armed forces. However, Lorenz was used only by Hitler and his top generals for strategic communications, and only around fifty were ever made.

Over in America, the intelligence cryptographers realised the Japanese Foreign Office used a cypher machine to encrypt its diplomatic messages. The device was called “Purple” by the Americans, and they built a machine capable of breaking this code. So with that sketchy prior knowledge from these diplomatic messages, could the attack on Pearl Harbour have been prevented in 1941? Unfortunately, despite numerous commissions and investigations over the years, there can still be no real answer to that question.

In May of 1943, as a result of an agreement between the US War Department and the British Government Code and Cipher School at Bletchley Park, the Americans established a branch of their Military Intelligence Service in London, supplementing the fifty personnel working at Bletchley Park.

Up until that date, the intelligence from the American Purple machine was called Magic. But after that, all intelligence gathered from the various cypher machines was then called Ultra by all the Allies. 

So what was the process for producing Ultra intelligence?  The Government Code and Cipher School at Bletchley Park received high-level enemy wireless traffic from intercept stations (known as Y stations) dotted around the UK and also abroad from such places as Malta. 

In the case of Enigma, traffic was in Morse code; or in the case of Lorenz, it was in the form of wireless teleprinter language. At Bletchley, the traffic was decoded by hand but, where possible, with help from new inventions: Bombes in the case of Enigma; Heath Robinson, Colossus (Marks One and Two) and the Tunny Decoder machine in the case of Lorenz.

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The decoded material was then translated, corrected, analysed for intelligence, comments attached; before the messages were sent to the relevant recipient via the special liaison units.

Since 1974 material has gradually been made available about Enigma and Ultra, not only from public records but also from personal testimony.  However, a significant part of the story, the Lorenz cypher machine and its codebreaking, remained classified until 2002.  By that time, most of the veterans were no longer alive.  However, Captain Jerry Roberts, who died in 2014, aged 93, was able to give details of the Lorenz machine and the Tunny code during the last years of his life. Jerry Roberts was a skilled linguist, fluent in German and a formidable codebreaker.

Enigma and Bletchley Park are regarded by many as synonymous, and this has all but eclipsed the Lorenz story.

Also, by the very nature of secrecy, work was compartmentalised. So, for example, intelligence analysts in Hut 3 would have had little idea of what was going on in Hut 6, where the codebreakers worked. So one person could not give a comprehensive account of what went on at Bletchley in all the different sections.

Another example was the “Testery” (named after Ralph Tester), which for twelve months from mid-1942 undertook all of the Tunny code-breaking stages by hand, did not engage personally to any great extent with the “Newmanry” (named after Max Newman) after it was set up in mid-1943.

Instead, the Newmanry concentrated on providing machine assistance for the codebreaking. Its first task was to commission the Heath Robinson machine, which electro-mechanically worked out some of the wheel patterns of the Lorenz machine for the particular message to be decoded.  In 1944 Tommy Flowers, a Post Office engineer, created history by developing the Colossus computer, which used thermionic valves (vacuum tubes).  Colossus, Marks One and Two, increased the speed, reliability and capacity of what the Heath Robinson machine attempted to do.

The Testery, in which Jerry Roberts was a founder member, consisted of linguists with a knack for code-breaking by hand, and the Newmanry consisted of mathematicians and engineers. They were not naturally of the same tribe and did not understand each other’s work; only the result of their work. 

I believe there is now enough published material to give a balanced account of the Ultra story, and I do not think there are any more secrets or personal testimonies yet to be unveiled.  However, Captain Jerry Roberts’ Lorenz book was published posthumously as recently as 2017 and revealed just what went on in the Testery.

Much of the information already published is just plain wrong when it describes the breaking of Tunny.  The misinformation is that it took weeks to break the Tunny code by hand.  Jerry Roberts says he was breaking several messages by hand alone during an eight-hour shift. 

The problem was that the hand breaking methods couldn’t keep pace.  The German operators tightened up their security and the number of messages kept increasing.  Skilled codebreakers were a scarce commodity; that is why the introduction of the Colossus computers was so vital. During the war 64,000 Tunny messages were successfully decoded; the majority were with the assistance of Colossus.

The combination of computer and brain power meant that only ten per cent of all encrypted Tunny messages received by Bletchley Park were unable to be broken.

Several Tunny messages Jerry Roberts personally broke by hand in early April 1943 gave details of the planned German offensive in the Kursk area on the Russian front, which began on 5 July 1943.  This information was passed to Stalin and, together with local intelligence, enabled the Russians to prepare for the forthcoming battle.  By winning this major strategic battle, albeit with massive casualties, the Russians turned the tide on the Eastern Front.

How Stalin received the information is another story. It involved the Soviet spy at Bletchley, John Cairncross—the fifth man of the Cambridge five spy ring—sending Ultra decrypts to Russia via his handlers. It also involved a secret service ruse of a supposed German spy sending details to the British. 

This information (its real source at the time was thought to be disguised) was then passed on through the British Military Mission in Moscow. How much Stalin knew about the actual code-breaking at Bletchley remains open to debate. What he did know, though, three months in advance, were the intentions of the Germans and a breakdown of all their forces that were to be used for their offensive.

Bletchley Park and Ultra have now been brought to wider public attention with films such as the 2015 “Imitation Game”, but in many aspects, the film is inaccurate and gives a false impression of what went on at Bletchley. It deals solely with Enigma, and even then, the plot plays lip service to reality. 

I would like now to deal with the Enigma and Lorenz cypher machines themselves: how they worked, how they were used and how the codes were broken.

Enigma

Enigma, the three-wheel cypher machine, was:

• Declassified in the 1970s
• Used from 1923 onwards, for air, land and sea traffic
• Well known through print, television and film

There are some excellent websites that explain the Enigma story and how the Enigma machine code was broken. 

It is in this Enigma story that Alan Turing and Gordon Welchman are the real heroes.  It is not, in my opinion, an exaggeration to say that by breaking the naval Enigma code, Alan Turing helped Great Britain survive during those dark days of 1941. 

By knowing the U Boats’ positions, convoys could be rerouted so vital supplies of food and materials could still reach Britain. However, there was an intelligence blackout in the summer of 1942 when the Enigma key settings changed and that resulted in widespread shipping losses.  Fortunately, Alan Turing broke the revised code in December 1942.

John Harper has published some web pages (bombe.org) which give a wealth of detail about the Enigma story so you can dip in and out as you wish.

The Enigma Machine – bombe.org.uk

Enter Turing and Welchman – bombe.org.uk

The two Numberphile videos (links below) are, in my view, a revelation. They explain in very simple terms the workings of the Enigma machine and the flaws built into it, and also how these flaws enabled the codes to be broken. The major drawback was that no letter could be encrypted back to itself. 

The casual reader may like to forego the two videos by Dr James Grime. However, they are not technical, and each has had over four million views.  

The first video, twelve minutes, explains how the Enigma machine worked:

The second video, eleven minutes, explains how the code was broken:

Lorenz

  Lorenz, the twelve-wheel cypher machine was:

• Declassified only in 2002
• Used from 1940 onwards by the German Army
• Used by Hitler, his high command and top generals
• More advanced, complex, faster and more secure than Enigma

Watch these two short BBC video clips, each of about two minutes. 

In the spring of 1942, Bill Tutte worked out the logical structure of the Lorenz machine without ever having seen it. This feat has been described as one of the most outstanding intellectual achievements of the war. 

It took him nearly three months of concentrated effort with a pencil and paper, sitting quietly in the research section at Bletchley. Once they knew the logical structure of the Lorenz machine, the codebreakers in the Testery switched their efforts from another code to work solely on the Lorenz code (Tunny).

When they broke the Tunny code and the wheel settings discovered, they put the settings into the Tunny Decoder machine. They simply typed in the coded text, and the plain text came out in German ready for translation.  

The Tunny Decoder machine was the first of several to be commissioned. Heath Robinson, Colossus Mark One and Colossus Mark Two then followed. Without them, vital intelligence would not have been available to the Allies.

The casual reader may just like to be content to know that the people who designed and built the machines were geniuses and leave it at that. The heroes of the Lorenz story are Bill Tutte, Tommy Flowers and Alan Turing.

Bill Tutte’s home town of Newmarket in Suffolk, where he was born, built a memorial to him in 2014. The website also has details about Bill Tutte’s life and the codebreaking of Lorenz.

In 2020, Martin Gillow, a computer programmer, produced a website that answers in a more technical way nearly all the questions relating to the Lorenz cypher machine and how its code was broken. 

The page explaining the Newmanary machines is shown below, but as I mentioned earlier, he is wrong to say the hand breaking of messages took weeks because one message could be done in a matter of hours. There were just too many messages to be decoded by hand by skilled linguists.

Virtual Colossus – The coming of the machines

If you would like to go into more detail, visit this link and scroll down the page to see a list of all its contents and select what you would like to read.  

Included is also a twelve-minute video by Dr James Grime explaining how the code was broken by hand and how the machines dovetailed into that process:

From the website, you may like to try the “Virtual 3D or 2D Colossus” and for any self-confessed geeks out there, try some simulations.

The real story of Bletchley Park and Ultra is one of teamwork on a massive scale, in which good management and effective procurement were just as crucial as individual scientific genius. Turing, Welchman, Tutte and Flowers did not win the war by themselves; however, without them, the outcome of the Second World War in 1945 may have been very different.  

Sir Harry Hinsley, who died in 1998, was employed in Naval Intelligence at Bletchley during the war and later became an eminent historian at the University of Cambridge. By using a technique called counterfactual history he calculated that Ultra shortened the war in Europe by not less than two years and probably by four years.  He readily admitted that such a strict calculation could not take into account something like the development of the atomic bomb by the Americans in the second half of 1945.

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Ultra, however, did not give unambiguous intelligence on nearby German troop dispositions before the battle of Arnhem (August 1944) and on German preparations for the Ardennes offensive (December 1944), with both actions leading to many Allied casualties.

But an indisputable fact remains: Ultra was overall of “priceless value” to the Allies. 

So to sum up, thanks to the hero codebreakers and all staff at Bletchley Park, Ultra:

• Helped to win the Battle of the Atlantic against the U boats
• Saved Egypt from being overrun in the Western Desert, thereby protecting the Suez Canal and the Persian oil fields.
• Provided vital intelligence before the decisive Battle of Kursk on the Russian Front
• Provided vital intelligence for the planning of D Day; without it, it is doubtful the D Day landings would have succeeded in 1944
• Saved the Anzio beachhead in Italy from annihilation
• Gave strategic information on the Italian campaign, thereby tying down one million German troops in Northern Italy
• Provided various tactical intelligence in the Battle of Normandy and the South of France landings, thereby reducing casualties

One question remains, however, Why was the Lorenz cypher machine only declassified in 2002? Could it be that Government Communications Headquarters (GCHQ) at Cheltenham were still breaking Lorenz type machine cyphers after the war and that valuable intelligence was still being produced? 

A theory is that the Russians never realised Lorenz had been broken (Enigma – yes), and after the war, they used captured machines for communications in the Warsaw Pact countries early in the Cold War. 

However, in 1956 the Russians introduced their own cypher machine called Fialka for use in the Warsaw Pact. It used punched tape and had ten rotors. It was declassified only in 2005. Was this code broken by GCHQ? There is no evidence that it was.

As of yet, there is no public explanation of why the efforts of Bill Tutte and Tommy Flowers were kept secret for so long and therefore became Bletchley Park’s lost heroes.

Secrecy was not always maintained as Russian spies in the 1960s and 1970s (Geoffrey Prime at GCHQ England, John Walker and Christopher Boyce in America) damaged the Allies’ code-breaking efforts for several years.

Even now, in 2021, internet and mobile phone surveillance can dominate the headlines in the age of the internet and smartphones. The Edward Snowden affair of 2013 still has repercussions. He finally defected to Russia after stealing a vast quantity of documents from his employer, the National Security Agency in America and disclosed surveillance methods employed by America and its Allies in intelligence.

It would be interesting to surmise what is happening nowadays throughout the world in codebreaking, surveillance and covert malware. 

In the interests of our own UK national security, I wonder what tasks the many thousands of people who are now employed at GCHQ Cheltenham are engaged in?

Such knowledge would be secret or to use an old code word “Ultra” secret.

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