Codeword Overlord

by Nigel West

  Upon taking up his appointment, Wild split Ops (B) into an intelligence sub-section, headed by Jervis Read, and a Special Means sub-section led by an inspired peacetime architect, Roger Hesketh. Wild, Jervis Read and a third ‘A’ Force veteran, David Strangeways, would form the core of BODYGUARD, the cover plan designed to conjure plausible Allied threats to Norway, code-named FORTITUDE NORTH, and to the Pas-de-Calais (FORTITUDE SOUTH). Also assigned to Ops (B), to work alongside Strangeways, was the first American deception officer, Colonel Temple.

  Their first task, though euphemistically termed ‘Special Means’, was to promote certain falsehoods, such as a shortage of landing craft and other equipment, to give the impression that the planned assault timetable would have to be delayed. The second was to suggest road-widening schemes in Portsmouth and Southampton were underway, albeit at a leisurely pace, to accommodate major road traffic. In the same vein, artesian wells were being sunk in the Kent countryside in preparation for the arrival of new military encampments in the south-east. Thereafter, the deception planners would apply their developed tradecraft to create wholesale misdirection, which they accomplished on an epic scale.

  The post-war recovery of FHW estimates gave a very clear picture of how the German assessment of the Allied order of battle had developed during the nine months before D-Day. This calculation did not allow for any Allied deceptive measures, but was drawn principally from SIGINT, aerial reconnaissance, prisoner interrogations and agent reports. A starting point might be assessment No. 36, issued on 7 October 1943, which described forty to forty-two infantry divisions (plus four independent infantry brigades); nine to ten tank divisions (plus eleven independent tank brigades), and two to three airborne divisions (plus seven paratroop battalions), making a total of fifty-one to fifty-four divisions and fifteen brigades.

  Two months later, assessment No. 42, dated 21 December 1943, showed little significant change, with forty-one to forty-two infantry divisions (plus five independent infantry brigades), eleven to twelve tank divisions (plus twelve independent tank brigades) and four airborne divisions (plus six parachute battalions); making a total of fifty-six to fifty-eight divisions and seventeen brigades.

  On 25 April 1944 FHW’s assessment No. 47 identified fifty to fifty-one infantry divisions (plus five independent infantry brigades), seven airborne divisions (plus eight parachute battalions), and fourteen to fifteen tank divisions (plus thirteen tank brigades), amounting to seventy-one to seventy-three divisions and eighteen brigades.

  On D-Day itself FHW produced a detailed estimate of the British, American and French formations in the British Isles, which it assessed as forty-one British infantry divisions (plus five independent infantry brigades), five airborne divisions (plus six parachute battalions), and ten tank divisions (plus thirteen tank brigades). The American contribution was considered to be thirteen infantry divisions, two airborne divisions and three tank divisions (plus one tank brigade), and two French parachute visions, adding up to fifty-nine infantry divisions (plus five independent infantry divisions), seven airborne divisions (plus six parachute battalions), and fifteen tank divisions (plus fourteen tank brigades).

  What makes these figures so remarkable is the constancy of their inflation, considering that on D-Day Eisenhower’s total Allied strength amounted to twenty-three infantry divisions, ten tank divisions and four airborne divisions, making a grand total of thirty-seven divisions, which means that FHW was out by some twenty divisions. In contrast, von Rundstedt commanded thirty-three static divisions in defensive positions; thirteen mobile infantry divisions; five panzer divisions and two parachute divisions, plus four panzer and panzergrenadier divisions in reserve, making a total of fifty-eight divisions. Furthermore, the OVERLORD plan called for just six or seven divisions to be landed on the first day, with the full amount of thirty-seven divisions not landed for some weeks.

  3

  LUFTWAFFE AERIAL RECONNAISSANCE

  ‘The part played by German air reconnaissance in assessing the Allied position was of major importance. A considerable amount of shipping would be involved in a large-scale invasion and must, of necessity, assemble at some point.’

  Colonel Walter Gaul

  At the end of the war advancing Allied troops discovered several caches of Luftwaffe aerial reconnaissance photographs, maps, target data and photo-mosaics concealed in various parts of the country. The project to assemble this material was code-named TURBAN and the bulk of it, amounting to 16 tons, was recovered from the German spa town of Bad Reichenhall, in Upper Bavaria, close to the Austrian border, designated DICK TRACY. Further archives were found in Vienna, code-named ORWELL; at Oslo, code-named MONTHLY; and in Berlin, code-named TENANT.

  In June 1945 the booty was crated and flown to the RAF Central Interpretation Unit at Danesfield House in Medmenham, Buckinghamshire, where the material was cataloged, analysed and prepared for post-war exploitation. The imagery, designated GX, proved to be the foundation of Allied geophysical intelligence and, in the total absence of Soviet maps, provided an unrivalled source of accurate information, especially about railway routes, until the introduction in 1954 of the U-2 surveillance aircraft, and then the CORONA satellite programme in 1960.

  The captured archives confirmed that Germany’s wartime aerial photo-reconnaissance (PR) capability on the western front consisted of Kampfgeschwader 51’s converted Junkers Ju 88 T-3 three-seater bombers attached to KG 54 which, with a top speed of only 317mph and a ceiling of 29,500ft, made easy targets for Spitfires unless they flew at very high altitudes. Although more than 1,000 Ju 88s had been built in the year before D-Day, most had been deployed to the Russian front and attrition rates had been so high that only two were available for missions over the Channel on 4 June 1944. The photo-interpreters were further handicapped by the camera equipment fitted to the aircraft, which was not stereoscopic and therefore did not offer the three-dimensional effect enjoyed by their counterparts at RAF Medmenham, who employed sophisticated electro-mechanical imagery apparatus that could detect and defeat camouflage netting.

  The Luftwaffe’s reconnaissance flights were limited by three factors. Firstly, Berlin had decreed that the defence of the Reich against Allied air raids should be the overriding priority, and the rate of attrition inflicted on the Allied daytime and night heavy bombers was viewed, over-optimistically as it turned out, as close to catastrophic, and certainly unsustainable. Fighters previously based at Lille, which had been vulnerable to surprise enemy raids, had been transferred to Metz in a ground defence role, and therefore were unavailable at short notice to engage in aerial combat over western France. Secondly, a shortage of aircrew meant there were fewer pilots available to be diverted to what OKL considered non-priority missions; and thirdly, the German Air Section at Bletchley Park, headed by Joshua Cooper, had concentrated its resources on monitoring communications to and from the specific units earmarked for reconnaissance flights. The traffic consisted of Enigma-encrypted radio messages and abbreviated signals sent in a three-letter hand cipher designated RHN that was known at Bletchley as RHINO.1 This source provided some significant (and comforting) information, such as evidence that the OKW had come to think that an invasion was likely at the end of April 1944, as indicated by the temporary assignment of four of the new, twin-engined Me 410 A-3 fighters to fly missions along England’s south coast, and over Scapa Flow.

  The RAF Y Service, having assigned intercept operators at Cheadle, Chicksands Priory, West Kingsdown and Church Green, was so successful in its blanket coverage of these channels that any attempt by Luftwaffe PR to penetrate British airspace would be detected and interdicted. Naturally, very high loss rates had an impact on morale and may have encouraged aircrew to find excuses to avoid flying.

  The German analysts were starved of material for a ten-day period in the middle of May 1944 when no reconnaissance missions were flown, leaving them dependent on results obtained on 25 April that had revealed 234 landing craft, 254 small boats and 170 auxiliaries mo
ored along the south coast and concentrated on Portsmouth and Southampton. According to Colonel Walter Gaul, formerly the Luftwaffe’s liaison officer to the Kriegsmarine, this single flight venturing over Spithead in the Solent, between Portsmouth and Southampton, spotted 264 Liberty ships, possibly tank transports:

  A photograph of the two harbours showed a collection of landing craft and other vessels which unquestionably denoted preparations for invasion; it comprised two battleships, six cruisers, thirteen destroyers and escort vessels, three submarines, eleven minesweepers, three tank transports, five hundred and ten landing craft of all descriptions, fifteen transports of 128,000 G.R.T., fifteen steamers of 19,000 G.R.T. and two hundred and ninety small vessels. The Germans calculated that this amount of shipping could transport three divisions. The assembly of ships at Spithead Reede was a striking one, resembling the preparations for the raid on Dieppe in the summer of 1942. Thus from the activity centred around the Portsmouth/Southampton area, this appeared to be the probable starting point of the invasion. The Plymouth/Brixham area, photographed from the air in the last week of April, showed landing craft capable of transporting 2½ divisions, which, together with two monitors, one battleship of the King George class and several large transports, might form a self-contained landing formation. On 27 April, in the Falmouth sector, ten tank transports and ninety landing craft were identified, enough for the possible transport of one division.2

  The absence of the Luftwaffe was noted on 6 May by MI5’s Guy Liddell, who recorded that, ‘The Germans are sending very few reconnaissance planes over here. During the last ten days, however, they seem to have confined themselves to areas west of Portsmouth.’

  The last PR missions were flown on 24 May that covered Bournemouth, Poole, Portland, Weymouth and several river estuaries.

  Folkestone and Dover were also photographed. Portland, Weymouth and Poole were particularly crowded with landing craft (LSI loaded with LCP) and all kinds of shipping. Twenty-five possible moles received special attention since the photograph of 25 May had already made mention of ‘large landing stages’ measuring 68 × 20m. Further efforts at reconnaissance on 28 and 29 May failed owing, partly, to British fighter defence, partly to icing conditions at a height of 11,000m. All in all it might be assumed that the landing craft comprised some 500 LST, approximately 3,600 LCT/LCE and 4,000 LCP/LCA and other smaller units. Including the merchant ships that were in readiness, the Germans calculated that there was transport for some sixteen and a half divisions; German estimates at the end of May and beginning of June 1944 put British and American forces in the United Kingdom and Northern Ireland at a total of ninety divisions and twenty-two brigades, comprising fifty-six infantry divisions, six infantry brigades, nine airborne divisions, seven paratroop divisions, sixteen mechanised divisions, sixteen mechanised brigades and twenty Commandos.

  These flights, penetrating the airspace over Dover, Folkestone and the Thames Estuary, were taken very seriously by von Rundstedt and Rommel, who noticed the lack of any apparent build-up in the number of landing craft moored in the Channel port harbours. Still convinced that the invasion was intended for an area north of the Seine estuary, they were reassured by the absence of naval vessels that no assault was imminent. On the issue of the concrete structures, known to the planners as PHOENIX, the German photo-interpreters could not agree on whether they were grain elevators, huge landing barges of a novel design, or maybe replacement jetties for damaged docks. This development became known on 19 May when Bletchley Park cryptanalysts solved a message dated 11 May from the Japanese naval attaché in Berlin who described Luftwaffe imagery taken the previous week that had shown a mass of landing craft in south coast ports, and some submersible pontoons that were thought to be prefabricated piers for some kind of harbour.

  Luftwaffe Enigma decrypts revealed that that the enemy had failed to complete a single overland mission between 25 April and 8 May, and confirmed that several attempts had been deterred over the sea by early interdiction by the RAF.

  German attitudes to PR differed markedly from the British, and was fragmented, with individual Luftflottes conducting their own operations for their own specific objectives. Furthermore, the interpreters tended to be NCOs, not officers, who were discouraged from specialising in any particular subjects. This meant the relatively junior personnel did not necessarily know what to look for, or how to recognise technical apparatus, such as the antennae associated with radar, which was considered secret. In contrast, the RAF’s work was centralised at RAF Benson in Oxfordshire, not far from Danesfield House, and most of the interpreters were well-briefed officers who had been indoctrinated into many of the secrets of Allied scientific intelligence, and therefore knew what to look for.

  By the middle of 1942 about half of the Luftwaffe’s reconnaissance aircraft had been shot down and, because of competing operational demands, the depleted squadrons were not replaced. The original Dornier Do 17s, operating at 20,000ft, were replaced by the Junkers Ju 88, which could fly faster and higher, but could not capture the same quality of imagery. Because of the high rate of losses, not a single PR mission was flown over London between January 1941 and September 1944, and when the Me 262 jet was deployed over the capital, to identify V-2 bomb-sites, the analysts had little to work on as their earlier pictures dated back to the bomb damage inflicted during the Blitz and it was hard to discriminate between the two.

  On D-Day itself SHAEF calculated the Luftwaffe’s strength in northern France at 1,750 fighters and 500 bombers, in comparison with the 7,500 aircraft available to the Allies, of which 3,200 were fighters. In reality Kampfgeschwader 51 only possessed 570 operational aircraft, of which 115 were fighters and 247 were bombers. On 5 June Luftflotte 3 had just 481 aircraft available, of which 64 were reconnaissance planes, and 100 were fighters.

  The Luftwaffe’s contingency plan for the expected invasion was code-named DOKTOR GUSTAV WILHELM, or DGW, which was an abbreviation of Drohende Gefahr West or ‘Imminent Danger West’ and involved the transfer at very short notice of 670 aircraft, including 475 fighters and 109 bombers engaged in Reich defence from Germany in just three days. The actual DGW signal was not authorised until 12 p.m. on D-Day itself, but over the following twenty-four hours an impressive 1,105 aircraft were delivered, including 24 reconnaissance planes, 83 bombers and 998 fighters.

  The consequence of very few Luftflotte 3 sorties, all undertaken at a safe height, was poor resolution over areas of eastern England where air interception was less intensive. These flights, undertaken by Gruppe 122 aircraft, returned with a product that enhanced the Allied deception campaign by revealing large numbers of what appeared to be concentrations of landing craft riding at anchor in harbours and river estuaries, whereas they were actually convincing-looking dummy vessels.

  Luftflotte 3, commanded by Hugo Sperrle from the Luxembourg Palace in Paris, relied on Gruppe 122/3(F), headed by Heinz Maetzel, and flew Messerschmitt Me 109s and Junkers Ju 88s from Soesterberg, 8 miles north-east of Utrecht in Holland, and on Gruppe 123/6(F) at Cormelles-en-Vexin, 16 miles north-west of Paris.

  The Kriegsmarine had always favoured the Seine estuary as the most likely landing area, pointing out the lack of Allied minefields in the area, the excellent beaches and their geographic protection from westerly gales provided by the Cotentin peninsula. On this basis the OKM suggested the end of May, as the tides, moon, weather dominated by light winds and maximum daylight all pointed to it.

  A study of Allied bombing raids noted that in April 1944 the number of enemy missions over France exceeded the 5,500 counted across the North Sea into Germany. The fact that the road and rail bridges along the Seine north of Paris had been targeted for special attention had been noted, but this obviously hampered road traffic in both directions and gave little indication of a potential invasion area.

  On D+1 Guy Liddell reported, ‘For the twenty-four hours preceding the attack the Germans did not send over a single reconnaissance plane to this country. The view is that they ha
d made up their minds that owing to the weather conditions no attack would take place.’

  4

  PROTECTING OVERLORD

  ‘The enemy would undoubtedly know that an attack was coming but it was desirable to conceal from them the exact date, time and targets and numbers of troops involved.’

  Guy Liddell, 6 October 1943

  The requirement to ensure that not even the slightest uncontrolled hint of OVERLORD’s objectives should reach the enemy was a top priority from the earliest moment that the operation was contemplated. Geographically, the British Isles enjoyed many natural advantages from a security standpoint, the only land border being with the Irish Republic. Wireless communications were monitored by the Radio Security Service, and the mails were subject to examinations and restrictions imposed by the postal censorship authorities. Air travel was also strictly curtailed, with civilian flights limited to and from Dublin, Lisbon, Madrid and Stockholm, and ships’ passengers were processed by MI5 Security Control Officers who directed arrivals to interrogation centres where their bona fides were verified. As D-Day approached, the radio links of diplomatic missions (apart from those of the embassies of the United States and Soviet Union) were terminated and three-day delays were imposed on overseas telegrams, the content of which was subject to paraphrasing.

  MI5 was closely involved in the D-Day planning from the outset, with Guy Liddell mentioning in his diary the reorganisation consequences in July 1943, and on 25 January 1944 he disclosed the strategic implications, as discussed that day by the JIC, to his diary: