I have argued elsewhere in this series of articles that it is a mistake to see ULTRA decrypts as a series of dramatic yet timely warnings and equally mistaken to overlook the value of information read, as it mostly was, after the events concerned had taken place. Although warnings would sometimes arrive over the next five years, what ULTRA did most of the time was enable the Allies to build up a picture of where Luftwaffe units were based; their subordination to higher echelons; who their officers were; their communications, state of equipment, logistical problems and modes of operation. This is apart from the insights into the Luftwaffe, unavailable from other sources, which ULTRA offers historians.
Even so, a warning from Bletchley Park on 12 September implies some concern that recipients were relying too much on deciphered messages:
That said, we now turn to what can be learned from ULTRA in the period 14 August–15 September 1940.
Efforts to install armour protection in all classes of aircraft and to increase the defensive armament of bombers continued throughout this period. One 13 August a signal from KG 55 disclosed that Landsberg, Leipheim and Gablingen would be fitting “MG’s 5 and 6 and oxygen apparatus No. 5” to 10 aircraft. On the 15th, the Geschwader’s II. Gruppe was advised that an He 111 it was expecting was having armour installed in Schwäbisch Hall; on the 26th Luftflotte 2 was allocated an He 111 H-2 with armour and “4–6 machine guns”. That this was mentioned at all is an indication that armour protection was not yet standard. The same day I./LG 1 was told that a Ju 52 would fly over 24 machine guns from Langenhagen. A message of 9 September advised that He 111 W.Nr. 2957, 2976, 2945, 2969 and 2950 had been armour-plated and would join KG 55. Unteroffizier Reichert of KG z.b.V. 1 was ordered on 2 September to take Ju 52 1Z+EY to Kölleda where he was to collect 15,000 rounds high explosive incendiary ammunition for the MG 131 heavy machine gun on behalf of KG 54 at Évreux.
Two messages sent on 13 August showed that I. and II./KG 77 were in Germany, at Illesheim and Füdstenfeldbruck respectively, receiving new Ju 88s. The same signals made plain that the Ju 88 was being produced by Siebel at Schkeuditz and Dornier at Oberpfaffenhofen. Fliegerkorps V directed on 24 August that until further notice Ju 88 formations were only to bomb horizontally and that dive-bombing must only resume on special orders from the Korps. On 2 September, 4U+OL of 3.(F)/121 landed in Würzburg owing to bad weather and a faulty fuel pump. It had been en route to Weimar and once it arrived was fitted with photographic apparatus, “bombing gear and machine gun roof” (presumably a bombsight, racks and the bulged Ju 88 rear canopy with two gun mounts) and armour. On the 7th however, the RLM told Obtn. Kurt Wenzel of 1.(F)/123 that long-range reconnaissance Ju 88s were not to be fitted for bombing and so his request for four M2 sets was declined. Two days later Wenzel asked that Ju 88s W.Nr. 379, 383 and 385 should have machine guns installed below and forward—»nach vorne unten«—as on W.Nr. 258. On 10 September the Staffel’s Ltn. Traffelmeier notified Würzburg that the first Ju 88 for fitting with a »Bildboden« (literally “picture floor”) would arrive the next afternoon.
The cockpits of ZG 2’s Bf 110s were being fitted with safety-glass panes on 26 August and Fliegerkorps V asked for a report on how many had not yet received them. As late as 10 September I./ZG 2 was reporting that none of its Bf 110s had yet been armoured. Deciphered five weeks after it was sent, a document of 27 July noted that so far nine Bf 110 had been refitted with DB 601N engines and another 15 would be completed by the 31st. A directive to use all surplus engines would permit the conversion of 100 machines during July and August; some of the work could be undertaken at Gablingen and might take around three weeks. On 1 September the Kommodore of ZG 76 told Hptm. Walter Grommes to organise the equipping of 36 Bf 110 the III. Gruppe with automatic variable-pitch propellers while on the 5th an element of the Geschwader asked when it would receive the rubber dinghies it had ordered. I./ZG 2’s Technical Officer on 15 September asked elements of the Gruppe at Dieppe-St. Aubin how many aircraft had not received alteration No. 90 to the DB 601, only to be informed in reply that nobody there knew anything about this modification.
A decrypt on 17 August had revealed details of the Bf 110 D series: the D-0 had a fixed belly tank; the D-2 had two external racks which could take either bombs or the belly tank; the D-3 could only carry bombs; and Staffeln were to be equipped entirely with the D-2 or D-3 to ensure consistency on operations. In so far as training “with the new type” (presumably the D-series) had yet to be take place, one Kette at a time should be attached to Erprobungsgruppe 210 for instruction. A month later, problems with the “Do. type (Me 110) aircraft” (i.e. the D-0: Enigma keyboards had neither a hyphen nor a zero) were coming to light and in the words of Bletchley Park, “A galaxy of senior engineer officers from Luftflotte 2, as well as Hauptmann Lutz of Erprobungsgruppe 210” (the Gruppenkommandeur) had been “conferring, writing and telephoning about this trouble”. Apparently as a result of ice forming in the rear fuselage, these machines frequently suffered damage at frame 18 near the dinghy stowage and at the tailwheel support. It was agreed that affected aircraft would go back to Messerschmitt at Augsburg for repairs and that the firm should work out how best to strengthen others of the type.
On 6 August the order had been reiterated that Bf 109s could only be employed as bombers after express instructions from the Luftwaffe Operations Staff, and Fliegerkorps V repeated that warning two weeks later. The same authority had issued directions on the 18th to JG 2 and ZG 2 that when their aircraft were operating in the normal fighter role ETC bomb racks and associated electrical connections could be removed. Luftflotte 2 was assigned two Bf 109 E-1b and one Bf 109 E-3b on 26 August to complete its reserve; they were to be delivered from Erding to Reims-Bétheny. Two days later came a request for the delivery by the 30th of the month of 20 Bf 109 and 15 Bf 110 “for the enlargement of our Staffel”. This mixed inventory suggests that the unit in question was Erpr.Gr. 210. The Bf 109 E-7 was just entering service and on 15 August JG 2 was due to pick one up from Romilly. Four days after that Kapitäne Ness and Fetzler were expected in St. Omer where they were to fit Bf 109s with special compass equipment.
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