Codeword Overlord

by Nigel West

  Feste 9 was a stationary intercept company formed in Frankfurt in spring 1942 and sent to Norway in July, but was subordinate to KONA 5. It was posted first to Trondheim, then to Bergen, and in spring 1944 was transferred to Ski, near Oslo. The company consisted of a headquarters platoon, an intercept platoon of 120 radio operators, a D/F platoon, a radio reconnaissance platoon of about twenty men and an evaluation section with a strength of about thirty. The evaluation section was divided into a sub-section for the evaluation of message content, one for traffic, and one for cryptanalysis. Between the summer of 1944 and the following winter, most of the personnel were moved to Italy to join KONA 7.

  Feste 12, consisting of a radio intercept platoon and a telephone communication unit, estimated at 120 men and 30 women auxiliaries, was subordinated to NAAS 5 until early 1944, when it joined Feste 3 to form NAA 12.

  FAK 624, comprised of an intercept platoon and an evaluation platoon, was formed in Montpellier in April 1943 and attached to KONA 5. In February 1944 it was subordinated to NAA 14 of KONA 5, and in the late autumn was combined with Feste 3 to form the reorganised NAA 14. FAK 624 was equipped with approximately eighty-five vehicles with six special French radio trucks and trailers for D/F equipment. The strength of the company was roughly 250 men including interpreters, code clerks, cryptanalysts, radio intercept operators and ninety drivers.

  In February 1944 FAK 613 combined with Feste 2 and Feste 9 to form NAA 13. When this battalion was broken up in late 1944, FAK 613 was reassigned to KONA 6, where it remained until the end of the war.

  FAK 626 was established in August 1943, trained until January 1944 and was activated in Winniza. Its original mission was the interception of 1st French Army and US Seventh Army traffic, and later that of the US First, Third and Ninth Armies. It was subordinated to KONA 8 and was stationed in the Ukraine. In October 1944, FAK 626 was sent to Landau, where it was trained in western traffic techniques and reorganised. In November 1944 it joined FAK 624 at Landau, and both units were posted to KONA 5. The strength of FAK 626 on the Russian front was around 250–300 men, of whom 80–100 men were intercept operators, ten to fifteen D/F operators, ten to fifteen cryptanalysts, five to seven translators, and ten were traffic analysts.

  In early 1944, when Army Group D was absorbed into Oberbefehlshaber West (OB West), which took control of three newly formed Army Groups on the western front, Army Group B (in northern France), Army Group H (in the Netherlands) and Army Group G (in southern France), KONA 5 was reorganised into three signal intelligence battalions, Nachrichten Aufklärung Abteilung 12, 13 and 14. NAA 12 was attached to von Rundstedt’s Army Group D, NAA 13 to Rommel’s Army Group B and NAA 14 to Army Group G. TICOM research established that Feste 12 had combined with Feste 3 to form NAA 12, and Feste 2 and 9 had amalgamated with FAK 613 to form NAA 12.

  Even by the exigencies of conflicting wartime priorities, it is clear that the frequent movement and restructuring of the German SIGINT capability lacked continuity and mitigated against the creation of expert cadres that could concentrate on particular categories of SIGINT. Nevertheless, the scale of the resources devoted to SIGINT surprised and impressed their Allied counterparts, and the evidence suggested that special measures had been taken to develop a dedicated, streamlined SIGINT system in the west. However, the changes came too late to cope with the challenge of the invasion, and MI-14, the War Office intelligence branch charged with the daunting task of studying the enemy’s order of battle, was clueless when it came to Axis SIGINT arrangements.

  KONA 5 remained unchanged throughout most of 1944 but later in the year, after the invasion, an attempt was made to centralise the western field organisation and a new senior communications intelligence post, the Hoeherer Kommandeur der Nachrichten Aufklärung (Hoeh Kdr D Na), was established with Colonel Walter Kopp attached to OB West, in charge of all SIGINT activities in the west, subordinate to Senior Commander of Signal Intelligence in the West, General William Gimmler. Additionally, KONA 6 was transferred from the Russian front to support KONA 5 and was assigned to Army Group B on the northern end of the western front.

  When this change occurred, KONA 5 was reduced to just two signal intelligence battalions, NAA 12 and NAA 14. NAA 13, which had been composed of Feste 2 and 9, and FAK 613 were disbanded and their personnel redistributed. Feste 2 was placed under direct supervision of Colonel Kopp; Feste 9 was shifted from Norway to Italy, where it joined KONA 7; and NAA 12 with FAK 613 was assigned to KONA 6. However, KONA 5 gained one long-range intelligence company, FAK 626, which was withdrawn from KONA 8 in the east.

  KONA 6, consisting of NAA 9 and NAA 12, had been created and activated in Frankfurt in 1941, and was posted to the Crimea. After the campaign in the Caucasus it was reassigned to work on the interception of Russian partisan traffic, and was finally transferred to the western front. When NAA 9 was withdrawn from the east in November 1944, it absorbed FAK 956, which had been established in October 1944, and the Long Range Signal Intelligence Company, FAK 611, which was also transferred from the east. This apparently endless process of reorganisation proved impossible to monitor externally, but reflected the strategic priorities of the Axis, such as the shift from the Russian front towards the west. Thus NAA 13 was assigned to KONA 6 from KONA 5 with the Long Range Signal Intelligence Company, FAK 613. Subordinated to NAA 12 were also FAK 610, which had been brought from the east in November 1944, and NAK 953, which had been reassigned from the east also in October 1944.

  FAK 613 was given by KONA 5 to KONA 6 in late 1944. TICOM could not find out much about this unit, but concluded that most likely it was the same as other Long Range Signal Intelligence Companies.

  FAK 6111 had been active on the eastern front during the Russian campaign from BARBAROSSA in June 1941, and had been stationed in Poland where it was attached to Army Group Centre. In November 1944, FAK 611 was moved to the western front and subordinated to KONA 6. NAA 9 was small enough to occupy a house at Zutphen, in the Netherlands, and consisted of thirty to forty radio and telephone operators, ten cryptanalysts and cipher clerks, and twenty-five analysts.

  FAK 610 had been activated in 1940 for operations on the eastern front, and from September 1940 was based at Tilsit, subordinated to KONA 2. Later it transferred to Volkhov, where it intercepted Russian traffic until November 1944 when it moved to the western front and was assigned to NAA 13 of KONA 6.

  These Wehrmacht SIGINT units, of which MI-14 had spotted only the faintest of traces, were considered by TICOM to be the foundation of all German intelligence assessments. Similar judgments were to be reached about the OKH/GdNA, as having accurately plotted the pre-war French, Dutch and British order of battle through a concerted cryptanalytical attack on the French codes and Dutch Army double-transposition ciphers, and through D/F and T/A operations aimed against the British Army. During the 1940 French campaign, with new opportunities offered by vastly increased traffic, it established the French mobile order of battle by cryptanalysis. OKH/GdNA also plotted the Red Army order of battle and located all the Soviet strategic reserves until 1943 through traffic analysis and cryptanalysis of the Soviet two-, three-, four- and five-figure codes, employed by both the Red Army and the NKVD.

  Thus, by a combination of conventional SIGINT techniques, the OKW had developed a comprehensive British order of battle, and exploited the traffic generated by the British Expeditionary Force (BEF) to complete an impressively accurate wiring diagram of the entire British Home Army. In his assessment of British radio procedures, General Praun expressed a favourable opinion:

  British radio communication was the most effective and secure of all those with which German communication intelligence had to contend. Effectiveness was based on World War I experience in radio procedure and cryptology, in which the British Army learned many a lesson from the Navy. The higher-echelon cryptosystems of the British were never compromised in World War II. The radio operators were well trained and performed their work in an efficient and reliable manner. Nevertheless, there were al
so some defects. Feeling safe because of the security of their cryptosystems, the British neglected to take into account the openings which their radio communication left to German traffic analysis. Plain-text addresses and signatures contained in otherwise securely encrypted messages revealed the make-up of the British nets and thereby also the tactical interrelationship of units in which the Germans were interested. The stereotyped sequence in which stations reported into their nets indicated the structure of the chain of command, while British field ciphers were too simple and did not provide adequate security over extended periods of time. Either the British overestimated the security of their own systems, or underestimated the capability of German communication intelligence. The same was true of the radio traffic of British armored units, which used such simple codes and so much clear text that the Germans arrived at the conclusion that the British were not aware of their field radio communications being observed.

  In spite of impenetrable higher-echelon cryptosystems, excellent operating procedures, and efficient personnel, the security of the British radio communication in the United Kingdom during 1940–42 and especially in Africa in 1941–42, was so poor that, for instance, until the battle of el-Alamein Field Marshal Rommel was always aware of British intentions.

  It was Rommel who repeatedly emphasized the predominant significance of radio intelligence reports in making an estimate of the enemy situation.

  In this connection it may be pointed out that by no means all German field commanders recognised the utility of radio communication and intelligence. Many of them were quite prejudiced against these technological innovations. This may help to explain why the performance of some field commanders and their subordinate units so conspicuously surpassed or fell short of the general average. They were the ones who either deliberately or unconsciously simplified or complicated their mission by making full use of or neglecting the facilities which were at their disposal.

  What surprised the Germans was that the many tactical successes scored by Rommel as the result of his unusually profound knowledge of the enemy situation did not arouse the suspicion of the British and lead them to the realization that their own carelessness in radio communication was at fault.

  As in the case of the other Allied armies, the Germans observed a general relaxation in British Army radio discipline, particularly in voice communication, during the course of large-scale fighting. As a result, the secrecy which had been maintained up to the beginning of an offensive was quickly lost. A few other deficiencies continued to be evident in British radio communication until the end of the war, such as for instance the inadequate encoding of place names in connection with grid co-ordinate designations.

  The surprise achieved by the British during their landing operations was remarkable. It was accomplished simply by imposing radio silences. The British Army probably acquired this device from [the] Navy.

  Only in very rare instances did the British observe radio silence during ground operations. It seems incomprehensible why the British military leaders did not impose radio silence and use it in its more refined form, that of radio deception, more often. By achieving surprise, even during relatively minor engagements, they would have been able to reduce their losses.

  In answer to the third question in this analysis it must be pointed out that even British radio communication was afflicted with a deficiency destined to compromise many of the Army procedures which had been so excellently devised and implemented. This deficiency was to be found in the radio communication of the Royal Air Force. The only possible explanation was interservice jealousy which led the RAF to overestimate the quality and security of its radio communication and to refuse to let it be subject to the supervision and control of the Army. At the same time Great Britain seems to have been without a unified armed forces command which would have restricted such separatist tendencies by exerting an authoritative, standardizing influence on the individual services.

  The RAF was certainly not aware, however, that it was responsible for revealing many carefully guarded plans of the Army and thus for many losses and casualties.

  Whereas the RAF failed to adopt the superior radio operation procedures of the British Army and Navy, other Allies who subsequently entered the war, especially the United States, introduced the proved British methods, much to their advantage. Only France failed to do so, much to its disadvantage.

  During the last year of the Italian campaign the exemplary conduct of the British, with their wealth of experience, confronted German communication intelligence with a variety of problems. In this slower and more orthodox type of warfare strict control by the British achieved a high degree of radio discipline and was able to eliminate most of the national idiosyncrasies that characterized their radio communication. The standard of security in the Italian theater was extremely high.

  Praun also commented on the US Army, although he was unaware at the time of writing that many of the supposed indiscretions in signals security that he had observed, and commented on critically, had been deliberately co-ordinated as part of Allied deception:

  American radio communication developed very much along British lines.

  Up to 1942 domestic military traffic in the United States and that carried on by the first units to be transferred to the British Isles, revealed certain distinctive features, such as APO numbers, officer promotion lists, end unit designations and abbreviations which were at variance with their British equivalents. German communication intelligence had no difficulty in driving wedges at points where these features occurred and in compromising the security of American radio communication. The manner in which the U.S. Army handled the traffic showed that its radio operators were fast and experienced. The comments made in the preceding section pertaining to the British cryptosystems are also valid for those of the Americans. The use of field cipher devices complicated German radio intelligence operations, even though their cryptosecurity was far from perfect.

  The Americans deserve credit for the speed with which they adopted British operating procedures in 1942. They must have recognised the progress made by their Allies, particularly after El Alamein.

  The Germans observed a continuous process of co-ordination aimed at eliminating the easily discernable differences between British and American procedures, except for linguistic differences which could not be erased. However, the radio discipline observed by the British and American units alike while they were stationed in the United Kingdom deteriorated rapidly and reached the very limit of minimum security as soon as U.S. troops entered combat. The abundance of radio sets with which the American units were equipped tempted the inexperienced U.S. divisions to transmit far too many CW and voice messages in the clear. They thereby provided the German command with many more clues regarding the tactical situation and U.S. intentions and enabled German cryptanalysis to solve many an American cryptosystem. This criticism pertains particularly to the initial engagements in North Africa, and to the subsequent actions in Normandy and France, and to a lesser extent to those in Italy. In spite of the training during combined exercises in the British Isles, the security of American radio communications was extremely poor. During the latter stages of the war the quality and security of radio communications was far from uniform in all the American armies. There were some armies whose radio traffic could hardly be observed, with the result that their intentions remained a secret. Other armies, either deliberately or unwittingly, denied themselves the benefits of radio security. Needless to say, in spite of their obvious superiority, this deficiency proved detrimental to them and resulted in needless losses.

  The comments made with regard to radio silence and deception in the section dealing with British radio communication apply equally to that of the Americans.

  Apparently there existed no centralized U.S. radio command agency responsible for raising the average performance to the quality and security standards set by the most disciplined units, or for keeping in check the arbitrary and unsatisfactory operating proce
dures of certain armies. Incidentally, the conclusions at which the Germans arrived on this subject were confirmed by MP radio operations during the Ardennes offensive. In this instance all established rules were violated and, given a somewhat less unfavorable distribution of forces, the final outcome might have been very different, since the German top-level command had complete information on U.S. plans and operations. These happenings were in paradoxical contrast to the otherwise exemplary security measures taken by the Americans.

  In conclusion, it may be said that the Americans’ higher-echelon nets were just as secure as their British counterparts. Tactical net operation should indeed have measured up to the required security standards. Actually, however, overall security was compromised by the many openings given to German communication intelligence by insufficiently disciplined lower-echelon units so that a maximum of security could have led to greater security among the U.S. forces in general.4

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  After the withdrawal of the BEF from France in 1940 the OKW had little opportunity in western Europe to conduct SIGINT operations against the British Army, apart from routine radio monitoring, but as the Libyan campaign developed, the focus of attention shifted to North Africa.

  During the offensive aimed to capture Tobruk the OKH/GdNA gave Rommel invaluable support by solving the super-encipherment of an unidentified British code system, and broke the US Army Converter M-209 traffic. Then, as HUSKY unfolded, the German defenders in Sicily captured a full month of keylists a fortnight before they were due to be introduced, a coup that also gave access to the US Army Field Codes 15, 16, 17, 21, 25 and 28, which allowed traffic from Iceland, England, Central America and North Africa to be read undetected, contemporaneously.

  Another of the OKH/GdNA’s successes, as TICOM learned much too late, was a daily solution to the British Slidex, usually within three hours, thus compromising a wealth of tactical information such as weather reports, Allied bombing and artillery targets. Of particular value were the daily returns submitted by US Military Police detachments that manned vehicle checkpoints in France after D-Day. These ‘stereotypes’ followed the same pattern and provided accurate details of all troop and vehicle movements at road junctions behind the front lines. In addition, the OKH/GdNA read some partisan channels from Yugoslavia and Greece, some messages transmitted by Czech and Russian agent networks, and by the Polish resistance.