by Barbara Bond
While the decoded letter shown above was concerned with planning escapes, Pryor also passed intelligence information back to MI9, as shown by the following letter, sent in December 1942. His original letter is shown first. The Censors would have been required to identify this as a coded letter, using such signs as the form of the date and the underlined signature.
Numerical writing style for the date and an underlined signature were both signs that a letter contained a coded message. See overleaf for the full letter.
John Pryor’s letter sent from Marlag and Milag Nord camp in December 1942. It contains hidden intelligence information.
John Pryor’s coded letter with hidden message highlighted
22/12/42
My dear Mummy and Daddy, The camps (3 x 5 grid) appearance is looking quite smart now as the main road(5) and paths inside the (4 – start alphabetical code) wire have been lined with small trees. Also our keen gardeners have dug flowerbeds in front of each occupied barrack. We were however forced to bring better soil in as most of our camp ground boasts only of sand in which nothing much will grow. Next spring when the new (5) plants are on the (4 – start alphabet code) way it should look quite respectable. We have just been working hard opening up our Xmas food parcels for this festive week, inside they contain several Xmas luxuries. Some have probably been on (5) view to next-of-kin at (4) the Red cross centres. The (5 – start alphabet code) parcels are certainly up to standard. Two or three days back a letter came from the Odell’s; Alasdair apparently has joined up and possesses Robert’s great liking for high speed travel on the roads. I have not played bridge (5) recently, but hope of (4) a rubber soon. The new (5) five-suit game sounds the (4 – start alphabet code) most complicated affair. My small model is really well underway and shows quite definite signs by now of resembling a real whaler. The contents of rubbish dumps (5) etc. are really just (4) the thing for getting the (5 – start alphabet code) odd little bits of wood and tin for it! As regards the clothing parcel suggestions. There is nothing I need really. But you ^already^ understand the few odd consumable things that one needs. I shall really be quite content even if they are underweight. Recently we had a large (5) number of books, but (4 – indicates end of message) mine have not arrived yet.
Heaps & heaps of love
your loving son
John.
The text with the hidden message highlighted is shown above, while the full explanation of the decoding is given in Appendix 10. The message hidden within this letter about the camp gardens and Christmas preparations was:
LARGE MUNITION DUMPS JUST SOUTH OF NEW BRIDGE AT NARKAU ON NEW BERLIN MARIENBURG ROAD
ORGANIZATION IN THE CAMPS
The level of organization in the camps dedicated to planning and executing escapes has been described in Chapter 4. Such detailed organization was also maintained so far as the coded letter system was concerned. The ingenuity required to compose a message that seemed like an innocent and innocuous letter to the family back home must have been very great and would have needed some considerable time. Time was something the prisoners of war had in abundance but they would also have needed their colleagues to keep watch to ensure that the activity was not discovered by the guards. The SBOs and the Escape Committees decided which messages were sent and by whom. They alone knew the identities of all the coded letter writers in each camp. New arrivals were interrogated by them and, if they knew the code, they were ordered not to send messages independently but only when told to do so.
There were reports from at least one camp, Stalag Luft III (Sagan), at the end of the war that mistakes had been made by MI9. The criticisms mentioned use of the same typewriter for letters to different individuals in the same camp; different signatures by the same fictitious individuals; one prisoner’s code key marked on the envelope instead of his prisoner of war number; use of similar notepaper for letters to different code users; and a lack of understanding in MI9 of the difficulties of keeping detailed records in the camps of all coded messages sent. Such detailed criticisms could only have been made by a team that was monitoring each and every letter. While the prisoners of war in each camp apparently knew that some means of secret communication between the camp and the UK existed, its precise form was known only to the SBOs, the Escape Committees and the code users. The activity was certainly managed in a highly controlled and meticulous fashion with considerable attention to the detail and the security.
A watchtower at Stalag Luft III. The official camp history criticized some mistakes made by MI9 in its communications with the camp.
ASSESSING THE CODED LETTER PROGRAMME
Two particularly remarkable points emerge from studying the exchange of coded letters. The first is the considerable degree of danger to which prisoners of war exposed themselves, not simply in planning their own escapes but also in sending intelligence information back to MI9. While the penalty for attempted escape was thirty days in solitary confinement, the penalty for providing intelligence was likely to be a session with the Gestapo for alleged espionage activities. Secondly, the sheer cleverness of the codes is strikingly impressive. Although the codes employed were described as simple by MI9, the finesse of the methodology was such that, as each was unique to the user, it was unlikely to be discovered. Since each code comprised three elements, two Arabic numbers and a letter of the alphabet, there were 2,600 possible permutations. This allowed for the existence of 2,600 coded letter writers, if each was to use a unique code. By December 1941 there were already 928 coded correspondents in operation and it was anticipated that this number would likely increase to 1,500 very rapidly. By the end of the war in 1945, a total of 12,500 coded letters had been despatched and received by MI9. The peak year was 1943, with a total of almost 4,500 in that year alone. By 1944, radio communications had been established in many of the camps and, together with the collapse of Italy, this resulted in a reduction of the coded letter traffic.
There is no evidence that a coded letter was ever deciphered by the Germans (or the Italians) or, indeed, that they were even aware of their existence, until the action by the British Military Attaché in Stockholm which might well have wrecked the entire system, but apparently did not. The difference in national approaches to the use of codes is also relevant. The Germans used a technical approach with machines to encrypt their coded messages, of which ENIGMA is the most famous. The British had always tended to regard codes and encryption as an intellectual exercise, preferring to use people rather than machines. Crosswords and chess were well-known as leisure activities in the UK; it was essentially the same approach of the application and discipline of intellectual thought and logic which allowed the coded letter approach to succeed as effectively as it evidently did. It was arguably this significant difference in national traits and practices which allowed MI9 to succeed with this most important link in the whole escape chain: it allowed the prisoners of war to indicate what they needed by way of maps and other escape aids and ensured that MI9 could respond by reporting what was being sent, to whom and when.
German soldiers in the field enciphering a message using the ENIGMA coding machine.
MI9 regarded the whole operation of coded correspondence as a success story. From their perspective, they took inordinate care with the operation of the entire system. They also recognized that integral to the success had been the outstanding security and planning which had taken place in the camps. It is, therefore, perhaps one of the most surprising aspects of the whole story of the coded letters to realize the extent to which it has not been addressed in detail by historians to date. Certainly Foot and Langley mentioned it in the history of MI9 which was published over thirty years ago and Green’s book tracing his own role as a coded letter correspondent with MI9 was published over forty years ago. Foot and Langley acknowledged Green’s book as their primary source and Foot emphasized in conversation as recently as January 2012 the importance of the coded letters. One might reasonably ask why that importance was not recognized by other histor
ians, especially those who more recently have had access to rather more open MI9 related files than Foot and Langley ever did in the 1970s. One might conjecture that the story has perhaps been overshadowed by that of Bletchley Park, ENIGMA, Alan Turing and his staff. For whatever reason, it is certainly the case that the coded letter story appears to have engendered no real interest or consideration by historians and, more particularly, by those involved in the history of British intelligence in the twentieth century. And yet, when one considers precisely what MI9 managed to do and what the prisoners of war managed to contribute in terms of current intelligence as well as planning escapes, it has to be acknowledged that this was a quite stunning contribution to the war effort.
The construction of the network of coded correspondence bears testimony to the extent to which escape had become a professional undertaking involving painstaking planning and execution. The programme of coded correspondence was every bit as carefully planned and executed in all its aspects as the map production programme and was a vital link in the escape chain. By this stage of the unfolding story, it is very clear that MI9 demonstrated the same professionalism, attention to detail and application in every aspect of the escape and evasion programme on which they had embarked.
6
THE SCHAFFHAUSEN SALIENT AND AIREY NEAVE’S ESCAPE
‘Life’s battles do not always go to the stronger and faster man, but sooner or later the man who wins is the man who thinks he can.’
(Anonymous, found in Airey Neave’s private papers)
The way in which the mapping programme was conceived, the significant resources which were dedicated to it, the ways of getting the maps into the camps and the method of coded contact have been set out in earlier chapters. There remains, however, the whole issue of how the maps were used in actual escapes and the extent to which they successfully, or otherwise, fulfilled their role. This aspect is first explored through looking at the escape route through Switzerland and Airey Neave’s escape using it. Neave’s escape, and further examples that follow in the next chapter, describe how the maps were used and the extent to which they were a key aspect in escape attempts: in essence, they demonstrate the geography of escape.
MI9’S ESCAPE ROUTES
Before considering individual escape stories, it is useful to appreciate some important aspects of the escape routes which were selected by MI9 and the critical extent to which MI9’s rationale for their choices was reflected in the escape and evasion mapping programme. It is certainly the case that there were more attempts and more successful escapes from German prisoner of war camps than there were from Italian camps. To a very great extent and in a surprisingly paradoxical way, this reflected German efficiency and Italian inefficiency. MI9 relied on German organization to deliver, in a timely manner, coded letters and parcels containing the escape aids. Italian ineptitude, on the other hand, meant that letters and parcels were often held up for months behind a wall of bureaucracy and sluggishness. MI9, therefore, appeared to concentrate resources on aiding and supporting escapes from Germany. Time was spent in documenting the passage of the coded letter traffic. Prisoners of war with whom MI9 was in coded contact were encouraged to acknowledge receipt of the letters they received. There were a number of examples of this in John Pryor’s letters. His letter dated 22/3/42, for example, contained a coded message which confirmed receipt of two coded messages from MI9
YOURS 24 DEC AND 3 JAN UNDERSTOOD . . .
The principal escape routes out of Germany which MI9 chose were south to neutral Switzerland and north via the Baltic ports to neutral Sweden. As Switzerland was landlocked, there had to be a further route out via France and Spain. This onward movement was through organized escape routes, among the most famous of which were the Pat and Comet Lines. The Pat, or PAO, Line was named after Patrick Albert O’Leary, the cover name of a Belgian national, Albert-Marie Guérisse, masquerading as a French-speaking Canadian airman, who established the escape route from Marseilles via the Pyrenees to Madrid. The Comet Line ran through western France and, similarly, across the Pyrenees to Madrid.
The Pat (PAO) and Comet escape lines through France to Spain are shown on this map.
Along these organized escape lines, the escapers were not on their own; they were accompanied by members of the Resistance, sometimes by paid guides and even, on occasion, by professional smugglers, who knew the terrain, so that large-scale mapping, in particular, was not required. A good example of this was coverage of the Pyrenees in [Series 43], described in Chapter 3 and listed at Appendix 5. The series covers Western Europe at a small scale (1:1,000,000) with four larger scale insets of border areas, and even those vary in scale from as small as 1:500,000, through 1:300,000 to the largest one at 1:250,000 scale. Two of the insets appear on sheet 43A and both are at 1:500,000 of sections of the Pyrenees across the French–Spanish border. MI9’s mapping resources tended to be concentrated on small-scale blanket coverage with large-scale coverage of specific escape points.
The largest centres of MI6/SIS activity during World War II appear to have been concentrated in Berne, Stockholm and Madrid, the capital cities of the three principal neutral countries in Europe, and the centres through which escapers would need to travel as part of their escape routes. SIS certainly ensured from as early as the summer of 1940 that they controlled the escape routes which MI9 sought to establish through the neutral nations. It was also the case that the section within MI9 responsible for this aspect of their work was run by Jimmy Langley who was in fact a member of SIS and was never actually appointed to the staff of MI9. (This aspect of the SIS–MI9 relationship will be considered in more detail in Chapter 9.)
Detail of the French–Spanish border, from [Series 43] sheet A. The red line shows the actual border and the blue line shows the northern limit of the forbidden zone.
ESCAPE TO SWITZERLAND: THE SCHAFFHAUSEN SALIENT
The first escape route covers the Schaffhausen Salient, a rather tortuously oriented section of the German–Swiss border to the west of Lake Constance, where a peninsula-like area of Switzerland projects into neighbouring Germany. It would have been the closest stretch of the border for those seeking to escape from Germany into Switzerland. This route was important in the greater scheme of MI9 organized escape, not least in terms of the success rate which attached to the attempted escapes across this particular border: almost 20 per cent of all successful escapes throughout the six years of the war were into Switzerland and the majority of those were along this route.
MI9 worked hard to identify potential escape routes and provide the necessary maps to help prisoners of war to escape. One of their most intriguing maps is sheet Y, a large-scale (1:100,000) map of the Schaffhausen Salient that is very different from most of the escape and evasion maps which MI9 produced.
Full extent of Sheet Y, showing the Swiss–German border region (reduced to approximately 1:200,000 scale to fit on the page and with text repositioned slightly to aid clarity).
Firstly, at 1:100,000, its scale is very much larger than most of their mapping programme. Secondly, it is clear that the localized area of coverage had been carefully selected to afford escaping prisoners of war the maximum chance of a successful escape. Thirdly, it contains a considerable amount of textual information, in military circles known as ‘goings’ information (terrain analysis), i.e. identifying and describing in considerable detail the significant features in the landscape which would help the escaper to navigate a successful route and also highlighting any features which would likely hamper or impede escape. The textual information on sheet Y commenced by stating:
Escapes into Switzerland have the greatest chance of success if attempted across the frontier of the Canton Schaffhausen. The region around Lake Constance is to be avoided.
Sheet Y was based directly on native Swiss–German topographic mapping of the border area and, because of the density of detail, the colour specification and the need to print on fabric (which had initially proved a considerable technical challenge
for the Waddington company), the one surviving copy of this sheet which has been identified, is quite difficult to read, despite its larger scale.
One of the unusual features of Sheet Y was the textual ‘goings’ information ranged along the northern edge of the sheet, with specific advice for escaping prisoners.
Detail from Sheet Y, shown at scale. The complexity of the base mapping and the relatively poor printing registration on the only surviving copy make it difficult to read. This area shows the Canton Schaffhausen, the frontier of which MI9 advised had the ‘greatest chance’ of escape success. The town of Schaffhausen is just right of centre on this extract, on the north bank of the river.
MI9 also produced cover of the same area at the same scale in two sheets, Schaffhausen Salient (West) and Schaffhausen Salient (East), marked respectively A1 and A2. Sheet A1 was produced as an escape and evasion map (see Appendix 1) but no copy of sheet A2 Schaffhausen Salient (East) escape and evasion map has ever been discovered. However, it is known to have been identical in specification to sheet A1 Schaffhausen Salient (West). A map of A2 Schaffhausen Salient (East), printed on paper, did appear in the Bulletin, and is reproduced here (see Appendix 9 for the Bulletin’s version of sheets A1 and A2). The significant difference between these two maps and sheet Y is that they were redrawn to a simpler specification to show only a selection of the topographic detail on sheet Y. Contours have been removed and elevation data were shown only in outline by hachures. The textual information has also been removed, but the man-made landmarks described have been included as annotations, for example, ‘the brickyards at Lohn’ on the western edge of sheet A2. The result is a considerable enhancement in the clarity and readability of the detail when compared to sheet Y.