Read The Secrets of Station X Online
Authors: Michael Smith
The Secrets of Station X (9 page)
But with the large amount of Enigma traffic pouring into Bletchley as the German
Blitzkrieg
engulfed first Holland and Belgium, and then France, the chances of Herivel’s idea
working
grew exponentially and, on 22 May, David Rees, another of the Hut 6 codebreakers, noticed that a number of the
indicators
in various messages for two days earlier were very close together. He tried all the different possibilities and managed to break the
Red
. It was one of the most decisive moments in the breaking of the Enigma cyphers, certainly of the Army and
Luftwaffe
cyphers. The
Red
would be broken from now on until virtually the end of the war and although the
codebreakers
clearly could not have known that, they were jubilant after weeks of only being able to break the
Yellow
, which was only used in Norway.
‘I can remember most vividly the roars of excitement, the standing on chairs and the waving of order papers which greeted the first breaking of
Red
by hand in the middle of the Battle of France,’ Stuart Milner-Barry recalled. ‘This first break into the
Red
was the greatest event of all because it was not only, in effect, a new key, which is always exciting, but because we did not then know whether our number was up altogether or not.’
It became immediately clear that the
Red
was the most valuable of the keys to work on. Far from being just a simple
Luftwaffe
key, it was the system used by the
Luftwaffe Fliegerverbindungsoffiziere (Flivo)
, the
Luftwaffe
officers
liaising
with ground forces to provide air support, and provided
copious details not just of what the German ground and air forces were doing at any one moment but of what they planned to do in the future. Although the invasion of France had brought a number of new Enigma keys, Hut 6 decided to concentrate its limited resources on the
Red
since
following
Herivel’s breakthrough they were now able to break it on a daily basis.
‘The volume of traffic on the one key was enormous,’ Milner-Barry said.
Over one thousand messages one day, which was broken by five in the morning. I cannot now imagine how, with our primitive methods of collecting and registering traffic, and our tiny staff for decoding it, we manage to cope at all. It is not at all easy now to recapture the atmosphere of those days. The main sensation of the newcomer was that he was participating in a miracle which he was entirely incapable of
comprehending
. I may say that this sensation has never entirely left me and that no amount of success staled the thrill of the break.
The long-term significance of the break into the
Red
using ‘the Herivel Tip’, or Herivelismus as it was dubbed by the other codebreakers, was not entirely clear at the time. But the
Red
key would never be lost again. It became Bletchley Park’s staple diet. It was used by countless
Luftwaffe
units and, because they needed to liaise closely with both the Army and the navy in order to provide them with air support, gave an exceptional insight into all the
Wehrmacht’s
plans for land operations.
‘From this point on it was broken daily, usually on the day in question and early in the day,’ recalled Peter Calvocoressi, one of the members of Hut 3. ‘Later in the war, I remember that we in Hut 3 used to get a bit tetchy if Hut 6 had not broken
Red
by breakfast time.’
There was very little that the Bletchley Park material could do at this stage to influence the Battle for France, but efforts
were made to develop the process previously used in Norway of passing the Enigma decrypts, now known by the codeword
Ultra
, to British commanders in France. This was done by an MI6 communications link to the headquarters of the British Expeditionary Force. A copy of the Hut 3 ‘agent report’ was passed to the MI6 Codes Section, which was based in Bletchley Park and which encyphered it using one-time pads, which when used properly are unbreakable. The encyphered report was then sent by motorcycle dispatch rider to the wartime headquarters of Section VIII of MI6, which was based at nearby Whaddon Hall, and from there it was sent on the MI6 radio link to the MI6 representative at GHQ in France. The codebreakers were jubilant when they decyphered a message giving eight hours’ notice of a meeting between the chiefs of staff and the four
Luftwaffe
formations involved but their joy turned to
disappointment
when the British commanders ignored the
intelligence
and the opportunity to bomb the meeting and kill key German commanders.
‘Valuable as this mass of Special Intelligence might become after analysis as the foundation of strategic knowledge of such matters as the enemy’s order of battle, it was clearly of little if any immediate tactical use,’ Birch recalled.
Hut 3 had not as yet the experience, the collateral information or even the reference books and maps wherewith to
disentangle
the obscurities of the German texts; few in the ministries could currently assess their significance in their disguised form, recipients in the operational theatre could only take them at their face value as agents’ reports; not many of them arrived in time for action to be taken; and even if all the material had been available and correctly appreciated, it is doubtful whether in the prevailing confusion, any practical use could have been made of it. Disguised and mutilated to resemble an agent’s report, it lost its integrity, did not inspire confidence and could not be correctly assessed.
But in real terms the dismissive attitude of the military at this time to any intelligence produced by Bletchley Park was irrelevant during the Battle for France, which was already lost by the time
Red
was broken. The Allied troops were already in full retreat and even if they had accepted that the intelligence was accurate, they would have been in no position to make proper use of it. Nevertheless, vital lessons were learned
allowing
the system to be revised so that
Ultra
intelligence could have a direct effect on any future campaigns fought by British troops. It was clear to Menzies and the directors of intelligence in the Admiralty, War Office and Air Ministry that they had to find a way to get the Bletchley Park intelligence, now distinguishable by the classification Most Secret
Ultra
which appeared at the top and bottom of each sheet of the reports, to commanders in the field, with someone involved in the reporting process on the ground fully aware of where the information came from and its true value while at the same time protecting it and limiting knowledge of the fact that the British codebreakers were
reading
the Enigma messages.
The issue was discussed at cabinet level and in mid-June 1940, the War Office set up a mobile Special Signal Unit, the role of which was to provide liaison with major commands so that
Ultra
intelligence from Hut 3 could be passed on direct. The unit was in fact run by Richard Gambier-Parry, head of Section VIII of MI6, and its original title of Special Signal Unit did not last long because the abbreviation SSU was assumed to be Secret Service Unit. The units were later split into two with Secret Communications Units attached to all major command posts to provide the communications links via which the
Ultra
intelligence would be passed and Special Liaison Units set up and controlled by Frederick Winterbotham, the head of the MI6 Air Section, alongside them passing the intelligence on to commanders.
Although it would be a year before the SCUs and SLUs would play their real role, they were to be critical to the future
use of
Ultra
intelligence by operational commanders. They were designed to provide the intelligence produced by the
codebreakers
swiftly and securely to commanders in the field. The SCUs were the communications experts linking the unit to the
codebreaking
centres, while the SLUs were made up of intelligence officers provided by MI6, who passed the
Ultra
material on to the commanders. Their role was to control the use of all
high-grade
signals intelligence, not just Enigma material, strictly to ensure that only those who had been indoctrinated knew of its existence. They also had to enforce the regulations on its use, making sure that it was never acted upon without a secondary source being available, to prevent any German suspicion that Enigma had been broken, and to liaise with the codebreakers on any queries from commanders.
The SLU officer was responsible for personally delivering the
Ultra
message to the commander or to a member of his staff designated to receive it. All messages were to be recovered by the SLU officer as soon as they were read and understood. They were then destroyed. No
Ultra
recipient was allowed to transmit or repeat an
Ultra
signal. Any action taken by a commander on the information given him by
Ultra
was to be by way of an operation order or command or instruction which in no way referred to the
Ultra
signal and could not lead the enemy to believe his signals were being read. No recipient of
Ultra
could voluntarily place himself in a position where he could be captured by the enemy.
The procedures used within Hut 3 were also altered in the light of lessons learned during the Battle of France. The amount of material coming in had strained its resources to the limit. Hut 3 itself became more organised and the number of staff increased with four reporters on each watch and with one officer from each of the Air and Military Sections of MI6 sat on each watch as Air or Army advisers, significantly
upgrading
the basic two-man watches that were clearly not sufficient during the fighting in Norway and France. ‘Hut 3 and Hut 6
were side by side,’ said Ralph Bennett, one of the watch
intelligence
reporters. ‘They were linked by a small square wooden tunnel through which a pile of currently available decodes were pushed, as I remember by a broom handle, in a cardboard box, so primitive were things in those days.’
The messages arrived through the wooden tunnel from Hut 6 in batches of between fifteen and twenty and were
immediately
sorted into different degrees of urgency by the Watch No. 2, or Sorter. They were split into four separate piles. Pile 1, by which the Hut 3 priorities would remain known throughout the war, was the most urgent messages. Pile 2 was less urgent but still needed to be processed and turned into agent reports within four to eight hours and Pile 3 needed to be reported but could be safely sent to MI6 headquarters at Broadway Buildings in London by overnight bag. The fourth pile was nicknamed the
Quatsch
pile after the German word for rubbish and did not need to be processed at all, although they were kept on file for future research.
‘Skimming the incoming material to assess urgency and importance remained the most responsible and tricky job,’ recalled Lucas.
It would have been sufficiently troublesome, even if all decodes had arrived in an easily readable state (as a small proportion did throughout), since the pure intelligence problems involved were often extremely difficult to solve on the spur of the moment – a difficulty which became even worse later on, as our work grew more complicated. But since a high proportion of decodes were corrupt, sometimes very corrupt, it was often impossible, on a necessarily cursory reading, to assess the importance, or even the simple sense, of a message. Thus, in times when there was much material (and in Hut 3 we usually had too much to do or else, though rarely, too little) the Sorter had a heavy
responsibility
, since by a simple mistake he could cause an obscure but urgent message to be laid aside for hours or even days.
Hut 3 was set up like a miniature factory with the Watch Room at its centre. The Watch sat around a circular or
horseshoe-shaped
table, with the Watch No. 1 at the head of the table, while the air and military advisers sat at a rectangular table to one side. There were up to half-a-dozen men on the Watch, each of whom had to deal with a message taken from the highest priority pile in which there were messages, first of all ‘emending’ them, i.e. filling in any gaps left because of radio interference or garbled letters, a process that had similarities to solving a
crossword
puzzle. They then compiled an alleged agent’s report based on the message, working from the original German, rather than translating it first, in order to guard against the introduction of errors.
‘The watchkeepers were a mixture of civilians and serving officers, Army and RAF,’ said William Millward, an RAF officer who worked in Hut 3 as an air adviser.
I cannot remember any women involved in this part of the operation, presumably because it was still thought to be wrong for a woman to work on the night shift or because it was thought to be a man’s job. At the rectangular table sat serving officers, Army and RAF, one or two of each. These were the Advisers. Behind the head of Watch was a door
communicating
with a small room where the Duty Officer sat. Elsewhere in the Hut were one large room housing the Index and a number of small rooms for the various supporting parties, the back rooms.
Once the watchkeeper had written the report it was checked by the Watch No. 1, who then passed it to either a military or an air adviser depending on the content. The adviser’s job was to ensure it made military sense and to add any comments on what was previously known about the unit before
passing
it back to the Watch No. 1 so that it could be teleprinted to London.
‘Material came in from Hut 6 in more-or-less cablese German and a lot of it corrupt,’ said Jim Rose, another of the air advisers.
Urgent messages were sent direct to Commanders-in-Chief. All messages went up to the service ministries. If the air adviser or the military adviser had anything to comment he was allowed to do so and then next morning we would send deeper comment to the Commander-in-Chief. Some of the information was tactically immediate, some of it was strategic and some of it was a build-up of order-of-battle, strength, weaknesses, supplies and so on, which most generals don’t know about their enemy. So it was very important in so many ways.