This article was prompted by a post on Neil Page’s (highly recommended) FalkeEins blog. Reviewing a recent book on the Battle of Britain, he remarked that it said nothing about ULTRA intelligence and its role in the campaign. Having already written something about ULTRA and Adlertag, I decided to look next at the period leading up to it.
Although the Battle of Britain continues to be written about 80 years after the events, the part played by ULTRA intelligence has received little detailed attention. It was never the sole source of intelligence on German dispositions and intentions: shot-down aircraft were examined, prisoners were interrogated, information passed through neutral embassies, aerial photos were taken, wireless traffic was plotted, useful knowledge was derived from newspapers and broadcasts. All of these methods contributed to the overall picture.
Deciphered signals rarely revealed the plans for a major air operation before it happened but offered clues which, taken along with other current and earlier traffic, enabled analysts to draw conclusions about the state of enemy forces, their capabilities, intentions and operational patterns (e.g. routine reconnaissances). In the summer of 1940 Bletchley Park had yet to build up the extensive card indexes that later in the war would allow it to make the most out of messages that on their own might seem inconsequential. Then they were encountering names, places and formations for the first time. The year had brought two major breaks into machine-ciphers: from the Norwegian campaign in early April and from the campaign in France in the third week of May. Since, except in rare cases, we do not have the individual decrypts, we do not know at what time each was issued. The only pinpoints we have are the times and dates of the compilations—sometimes three per day—of paraphrased information. From these it seems that traffic was generally being broken within about 24 hours of transmission but we cannot be more precise.
We do however have a description of the Air Ministry’s procedures for handling and distributing this special intelligence. The material came direct from the Secret Intelligence Service (M.I.6) by teleprinter and was handled by a staff of specially selected officers who were always on duty. A message of operational value went to the Duty Group Captain, “to take the necessary operational action through the operational director, or, if necessary, direct to to commands”. These items and ones which did not demand “immediate operational action but [did] require analysis” went to various sub-sections of the German Section to “extract … all information of value”, such as orders of battle, locations and commanders’ names. The Section would only ask for the German-language original in exceptional cases, where part the translation was in doubt.
With the end of the fighting in France imminent, it did not require secret intelligence to work out that Germany would now turn her armed forces against Britain. How soon this might happen and the form the attack would take were areas that ULTRA could shed light on. By 0700 on 20 June, the following information had been deciphered:
Late on 18/6/40 Luftflotte 3 gave orders that as the forces had suffered severe disintegration owing to operations being maintained on a wide front, their reorganisation was to be brought about by every possible means. Discipline had also deteriorated considerably and this must be rigidly enforced, primarily through the example of officers.
The rapid advances and flexible deployments of the past six weeks had come at a price and the Luftwaffe would evidently need some time to reorder itself for a new campaign. By mid-afternoon on the 20th there was a sign of where the next blow might fall: "A request for 400 copies of some publication entitled “Notes on English Navigation (or ships: Schiffskunde) — Schattenrisse (outlines or silhouettes) was made on 19/6 by Flakkorps I." Another translation might be “Notes on English Shipping Intelligence”, the silhouettes suggesting that this was a recognition manual. Within 24 hours it was also known that “the remaining aircraft” of I./KG 76 loaded with 250 kg bombs, had been ordered to St. André as a jumping-off airfield for an attack on shipping. Other messages suggested that this Geschwader was in some disarray since another nine “returning aircraft” were also to be rearmed and the Kommodore was demanding the immediate return of crews and machines loaned to the III. Gruppe). On the afternoon of the 20th, Luftflotte 3 ordered Stuka and fighter units to seek out advanced airfields in the Calais area. Another directive that afternoon had historical if not operational significance: Hitler had personally forbidden any flying over the town and forest of Compiègne. On the 21st, Flakkorps II reported that two Abteilungen had been sent there and the Franco-German armistice was signed in the forest the next day.
A message early on the 21st speaking of “Undertaking Strassburg” and “final position of ships etc.” was followed by one from Fliegerkorps IV describing the balloon and gun defences around Southampton. The British deduction that “Strassburg” was Southampton went untested as the operation was called off late in the afternoon. Over the next few days, British analysts remarked that II./St.G 2 and KG 1 were likely soon to operate against England, despite the latter having only 52% of its aircraft serviceable. The men, but not the aircraft, of III./St.G 77 were brought back to Köln-Ostheim for the setting up of “an experimental unit, ‘Gruppe 210’”. Some of I./ZG 1’s Bf 110s were to go there too, others being surrendered to ZG 26 “to fill up gaps”(see sidebar). Likewise 5.(F)/122 went to Münster-Loddenheide to refit. KG 2 on the 25th had 95 aircraft but only 53 serviceable. By contrast, Stab, I. and II./JG 53 had 67 Bf 109s ready for action but complained that shortage of fuel at Rennes and Dinan might prevent them from operating.
By the 27th Bletchley Park knew that KG 1 was returning individual Staffeln to Germany to overhaul their aircraft and that the III. Gruppe had none ready for action: it soon transpired that the latter was back on home ground “to re-equip … with technical apparatus in readiness for fresh operations”. On 29 June I./KG 1 had 11 machines serviceable and 19 not. For its part that day, III./KG 76 began an overhaul of its aircraft which was expected to conclude five days later; the Gruppe reported having 17 machines at “(UOF) Baden”—Schwäbisch Hall, perhaps—none of which was currently serviceable. Airmen of units moved to rear areas were to be allowed leave up until the day before their aircraft were repaired, with recall expected on 1 July.
JG 51 on 27 June ordered an immediate journey by car to scout two or three sites for jumping-off strips in the Boulogne – Cap Gris Nez – Marquise – Colombert area, dispositions well-suited to fighter operations against England. Two days later aircraft of the Geschwader asked that an afternoon sighting of a 32-ship convoy off Dover be passed to Fliegerkorps 2 “immediately”. On the 26th, Bletchley Park had issued a paper on “Reorientation of the German Air Force” based on the many unit locations disclosed by ULTRA. It noted that Western France had been allocated to Luftlotte 3, the East and Belgium to Luftflotte 2 and:
… As regards disposition of types of a/c we find the 2 O/C Fighters immediately on the coast, Jafü 3 at Lisieux and Jafü 2 at Étaples. A fringe of fighter units have been located along the coast, while the Kampfgruppen seem to be at Amiens, Beauvais, Noyon, Laon, Rheims, Mourmelon, Mézières for the most part.
Luftflotte 3 sent an urgent request to expedite the delivery of life-jackets, dinghies and “parachutes for emergency descents at sea” to FAGr. 123. By the end of the month, ZG 26 too was asking for these items, as was V.(Z)/LG 1 but the depot near Dreux had none in stock and wanted to know where it might obtain them. On 27 June the Luftflotte ordered a six-day withdrawal of one third of its units to make good damage and losses, as far as possible on their home aerodromes in Germany. The day also saw a strength return from Fliegerkorps I showing that Stab, I. and II./ZG 26 had 59 Bf 110 (34 of them serviceable) while KG 77 had 95 Do 17 (62 serviceable). The same report detailed the French bases of the constituent Gruppen but shortly afterward it was announced that the entire Geschwader was to convert to the Ju 88 on Bavarian airfields, starting in mid-July.
The logistical difficulties being experienced in France were illustrated by a warning about “entirely inadequate” fuelling facilities at Le Bourget causing 3-hour delays. A sign that there would be no immediate all-out assault was the amount of attention devoted to arrangements for a “a grand parade of the armed forces of the Reich” to be held in Paris sometime between 30 June and 7 July. Representatives of the various units were detailed to participate in a flypast and protection was to be provided by redeploying Flak batteries alongside several Gruppen of fighters and Zerstörer under the control of Jagdfliegerführer (Jafü) 3. The proposed date was soon put back to 15 July, then to the 23rd at the earliest, before cancellation was announced on 21 July.
continued on next page …