On 20 January, in the first of the unit’s operations for the year (as far as the Allies knew) an He 111 of the “Special Detachment” was due to take off at 2230 and cross the coast due west of Bordeaux, its return expected between 0630 and 0730 next morning. At 0557 F8+DI gave its estimated time of arrival at base as 60 minutes hence. It was over Mérignac at 0647 but was unable to land owing to bad weather and was diverted to Istres. Six nights later, the intention was for an He 111 to fly out at 2315 and return by 0800 the next morning. Aircraft “I”, using a II./KG 40 call sign, was in contact with Bordeaux shortly after 0200, when it was plotted about 360 km NW of Mérignac. Just over four hours later, F8+DI was heard in touch with ground stations at Dreux and Bordeaux.
The night’s operation by the Kommando on the 29th sparked a flurry of German activity when F8+DI called in a sighting of 200–300 landing craft 200 km west of Royan. The aircraft’s control ordered it to shadow at 0207, but it failed to reply to a call 20 minutes later. It probably did little to alleviate the tension that the crew was similarly unresponsive when asked at 0352 if it was indeed shadowing, and to a request at 0510 to report the vessels’ course. However the Heinkel was homing on Mérignac from the NNW at 0636. After surface units and submarines had been alerted, somewhat anticlimactically the supposed landing fleet was later found to have comprised a mere three dozen trawlers, half of them Spanish neutrals. Even so, a call came through from Gen. Jodl at OKW ordering the 8th Destroyer Flotilla to search the boats “for arms, radar equipment or evidence of British connections” but it seems the Navy was able to reassure him that this was a regular fishing ground and that all searches to date had yielded nothing.
Another aspect of the radio countermeasures war being played out in the Bay came to British attention during January. From the 18th there were operations from Avord by III./KG 40, “as yet unexplained.” A week later these were discovered to be by the 9. Staffel in cooperation with a patrol boat and by the first days of February, the vessel in question was known to be setting out reflector buoys intended to appear identical on radar to a U-boat. These were almost certainly the newly-introduced “Thetis” decoys which could also be deployed by the U-boats themselves.
A nine-hour operation was intended on 5 February but no corroborating W/T traffic was heard. The next day, an He 111 was due to take off at 2345 and come home between 0745 and 0845. Traffic early on the 15th would permit the identification of another of the Kommando’s Heinkels: DT+YI (He 111 H-16, W.Nr. 8308) homed on Bordeaux from 0614, giving its ETA as 0700.
More intelligence was derived the following day: the Kommando had become Horch- und Störstaffel 2 ("Listening and Jamming Staffel 2" to the Allies) and acquired its own unit code, 9U+_B. At 2230 it was reported that He 111, 9U+CB had taken off 15 minutes previously and would be returning between 0615 and 0715. (The same aircraft was identified in W/T traffic between 0228 and 0320 on the 17th). The intention for 16 February (communicated to destroyer ZH 1) was that He 111
A major Luftwaffe effort had taken place in the Bay of Biscay on the 25th, to bring home U-714 which was carrying the survivors of the scuttled U-545. However the submarine had docked in Saint Nazaire by 2230, the time the night’s He 111 was due to take off (with landing foreseen for 0600–0700 the following morning). On 29 February, destroyers ZH 1 and Z 23 were told that 9U+CB was to take off at 2215 and return to Mérignac between 0615 and 0715 next day but—as was far from uncommon—there was no intercepted W/T to show that this sortie took place.
Early in March the Kriegsmarine’s signals division held a conference on the radar war at sea and at least two of the papers presented discussed how Allied systems might be countered, passively or actively. Kapitänleutnant von Schultz provided the exposition that began this article; the former commander of U-106, Kptltn. Hermann Rasch (now head of Section IVD of the Naval Signals Service), offered an overview of the »Stördienst« (Jamming Service) covering land- and sea-based systems as well as airborne ones
Rasch makes it clear that only one airborne jammer was then available, »Kettenhund«, that it was effective only in the 1.20–1.80 cm waveband (the British A.S.V. Mk. II radar operated on 1.70 m) and was not being used on operations because the transmitter could act as a beacon to hostile aeroplanes and could interfere with the search and detection capabilities of the machine carrying it. There was currently no centimetre-wavelength jammer (to counter, for example, A.S.V. Mk. III on 10 cm) while the set under development, »Roderich«, was clearly disappointing.
Between them, Schultz and Rasch offer perhaps the best available picture of what Horch- und Störstaffel 2’s activities actually were, as well as clues to what it had not been doing. Intermittent sorties by one or two aircraft could never have interfered significantly with Allied radars over an area so large as the Bay of Biscay (c. 550 km North–South and 650 km East–West) although it is of course possible that individual jamming trials were carried out. Any local jamming support for, say, a returning U-boat would have been compromised the “beacon effect” mentioned above; a lone aircraft could however be very valuable listening-in on Allied radars and communications during anti-submarine operations. Monitoring electronic emanations was a well-established form of intelligence although in this case it seems that little of significance had been learned despite many months of operations.
The intention on 1 March was that 9U+CB should start from Mérignac at 2215 and return from 0600–0700. Apart from the marginally earlier landing time this mission profile duplicated the previous night’s, right down to the route (Mérignac – 24 West 3951–15 West 9053 – Mérignac) which may be a further indication that the original flight had not in fact taken place. At 2230 on the 3rd, the Luftwaffe issued “data for operation of Horch- und Störstaffel 2”: He 111 9U+CB had started 20 minutes earlier and was due to return between 0610 and 0710 but nothing was heard by the Y-Service. Again two destroyers, Z 23 and ZH 1 were notified and the aircraft was to transmit “858” if “ship targets” were located.
Notice was given on 9 March that an He 111 would be in the air for “target practice” in the vicinity of St. Nazaire from 0900–1100 and again from 1300–1500; on the morning flight it was to drop »Folien« (“foils” = Window) from 0930, suggesting an exercise for radar crews. In 1943 there had been frequent target-towing flights aver the French Atlantic ports, usually by types such as the Fw 44 and Ju W. 34 but these would not suffice for the task at hand:
Although passive jamming was involved, it is far from certain that this was a Horch- und Störstaffel operation since “target representation” was a role normally undertaken by those elements of Fliegerzielgeschwader 2 based in France.
On 20 March the Y-Service picked up traffic from a “new” He 111, 9U+AB, as it was returning to base early in the morning; it had taken off at around 2220 the previous night. Single Heinkels were due to fly on the nights of the 21st and 23rd, concluding known operations for the month.
continued on next page …