German SIGINT in the Desert Campaign

The story of Capt. Seebohm has reached almost mythical levels when it comes to reviewing the part he played in Rommel’s successes in the Desert campaign. Rommel had arrived in Tripoli on 12 February 1941 for ‘Operation Sunflower ‘ (Operation Sonnenblume) the deployment of German troops (the Afrika Korps) to North Africa in February 1941. These troops were to reinforce the remaining Italian forces in Libya after the Italian 10th Army had been virtually destroyed by British attacks during Operation Compass.

Capt. Seebohm and his unit had docked at Tripoli on April 24th together with another radio intercept platoon, a radio direction finding platoon, and a group of cipher specialists under Lt. Wischman. In all more than 300 men of the sigint company linked up in Sirte. The unit’s nomenclature initially was 3rd Company attached to the 56th Signals Battalion. It did not become the 621st (as it is always known) until April 1942, in a move aimed at deceiving the British.

Lt. Wischman, who later had the good fortune to be attached to Rommel and was not with Seebohm, when the unit was attacked thus avoiding capture, said in 1974: ‘Captain Seebohm was extremely ambitious and always wanted to win glory in Rommel’s eyes by obtaining impressive results from our company. For that he needed . . . a site for our radio monitor offering good reception conditions and the possibility of picking up all the important enemy wireless nets loud and clear . . . Rommel thus often had signals in his hand before the enemy commanders to whom they had been addressed’

Seebohm’s 621st Company was merely a set of ears for Rommel and it is important to keep this in context as its reputation and importance have grown over the years. This is not an attempt to downplay the unit’s successes; rather, it is simply putting them in perspective. Too often there is a tendency to attribute success in intelligence to a single source. The 621st certainly provided some excellent intelligence all on its own but many of the unit’s successes are better described as ‘successes of German intelligence’; combined efforts in which the various sources worked together, fusing their outputs to give a much better picture than any one of them could individually. Undoubtedly the combined loss of Fellers and then of Seebohm later, would prove to be a disaster for Rommel.

Seebohm issued his first report on May 2nd only days after arriving in Tripoli. But the best reports in the world are meaningless if they arrive too late. Rommel was always on the move, so Seebohm attached a small liaison team that travelled constantly with Rommel. Seebohm’s first success was in mid-May when the 621st correctly evaluated British movements as ‘offensive’, allowing Rommel to respond quickly. They did not predict the offensive, but they did take note of the various indicators  that had occurred before it, especially the use of a single codeword sent to all units.

The direction-finding platoon detected a shift of British armour on the Sollum front in early June and Seebohm correctly deduced that another offensive was in the making. On the evening of June 14th, the use of a single codeword was heard again. Seebohm informed Rommel that a British offensive was imminent and Rommel immediately shifted his forces. The British BATTLEAXE offensive started the next day. The German unit intercepted a lot of significant traffic in the clear during the battle, including British commanders debating what to do and units complaining about the lack of ammunition – all in plain language! The capture of a British code book early in the battle also helped the 621st, giving them a much better understanding of what they were hearing—including a message that indicated the British now intended to retreat. After these disclosures, (following the capture of the 621st) the British finally tightened up some of their radio procedures. Not surprisingly, it worked. Radio silence allowed the British 7th Armoured Division to withdraw undetected. The 11th Hussars and the 4th South African Armoured Car Regiment switched radio operators, a move that deceived the 621st as to which unit they were hearing.

Radio intercepts weren’t the only source of information; successes also came from close cooperation with other intelligence sources, for example, a reconnaissance regiment was detected by the 621st and their position was then confirmed by German air reconnaissance. The same procedure confirmed the location of the 1st South African Division in early November 1941.

British communications security was considerably better by their November CRUSADER offensive, and their units got into their assembly areas undetected by the 621st. However, a captured code list once again aided the unit during a British offensive. Seebohm learned that the 5th South African Brigade had been destroyed, as repeated calls to it were not answered. The offensive lasted long enough for the 621st to once again compile a revised Allied order of battle. Seebohm noted the 70th British Infantry Division was newly deployed at Tobruk. His direction-finding platoon detected the British withdrawal as the locations of the various divisional  headquarters shifted to the rear. In January 1942 the 621st learned that the 2nd New Zealand Division was leaving due to a careless message in which they said goodbye and wished the other units well. They had been mauled in CRUSADER and were withdrawing to Syria. Seebohm learned of the British retreat on January 24th. The 621st detected units of the 1st Free French Division in late January. Direction finding was also quite active, placing the 11th Indian Brigade at Maraua, the 1st South African Division at Bardia, and the 1st Armoured Division at Mechili.

One of Capt. Seebohm’s platoon commanders, Lieut. Heinrich Habel had asked Seebohn earlier in July why he had sited his ‘Circus’ – as the soldiers dubbed their unit with all it antennae, tents and buses – so far forward.  The answer was a cynical

– “A fine thing to ask me now!” Habel later learned that a ‘Colonel’ had reprimanded Captain Seebohm believing he had left his position (perhaps at Matruh) too early. The  colonel  concerned  had  evidently  not  realized  that  this  company  was  not a

rearguard combat unit but a precious, an almost irreplaceable Intelligence gathering operation. Bound bt secrecy, Seebohm was in no position to correct this misunderstanding. This could well have been the thinking behind his staying and fighting.

In late June, I n preparation for Rommel’s next attack – on the Alamein position – Seebohm had taken up a position on the sea coast on the Tell-El-Eisa plateau west of Alamein, just west of the hill-top which made an excellent site for intercept and D/F, about 600 metres behind the front which was being held by the Italian’s Sabratha Division. It was an exposed position for the main body of an intercept unit to take up but it was well suited for D/F. This was possibly not the only reason for the choice of the site. Seebohm wanted to continue to shine in the estimation of Rommel by producing more and more high quality intelligence. What Seebohm really wanted achieve for Rommel was to discover the British headquarters nets at the brigade level and higher and he found them. The intercept operators continuously monitored the frequencies of these nets, copying and passing along all traffic on them. The direction finders did their part by making sure that the stations in these nets were still in the same locations as previously determined or found their new locations.

The British identified the unit by air reconnaissance flying over its position. They also intercepted and decrypted the Enigma traffic between the unit and the evaluation centre. The British were now fully aware of the company’s mission and planned a raid. Australian troops led the raid on the night of July 10th. Italian troops co-located with the intercept platoons fled. Seebohm happened to be visiting the intercept platoons at the time. Both he and the unit fought as best as they could, but rifles and machine guns were no match for tanks. Seebohm was wounded and died soon after. Seventy-three men of the intercept platoons were captured, along with their equipment and a treasure trove of documents detailing what the unit had done and what they knew. Most of 621 Company Radio Intercept Company was overrun and destroyed as a result of being too far forward at its operating position near Tell el Eisa, and its entire documentation was captured. The operations report of Panzer Armee Afrika related:

“‘Whereas in the south the attack was making good progress and promised well for the next day, on 10th July 1942 at 0600 hrs, the enemy attacked the (Italian) Sabratha division north of the coastal road with a reinforced brigade. After laying down a preparatory artillery barrage for one hour, and with tank support (from the 9th Australian Division) the Australians attacked. The Italian troops, whose artillery seems to have consisted of one light artillery battery and one heavy artillery battalion, either surrendered without resistance or took to their heels. The Sabratha division was largely wiped out or captured and lost its entire artillery except for the heavy battalion. As a result, the Australians advanced so quickly that they were able to destroy or nearly the whole of 621 Radio Intercept Company”.

In the face of a sudden attack at 6a.m by an Australian force led by tanks and preceded by a heavy artillery barrage, the Sebratha Division melted away leaving Seebohm to stay and fight on for a further 11/2 hours, armed with little more than L.M.G’s until they were overwhelmed and 69 survivors taken prisoner, only a few wagons escaping with baggage.

When captured, Seebohm was found to have the British Call-sign book currently in use in the Middle East. In addition, he had the British Map Reference Code for the attacks that would culminate in the attack on El Alamein. with identifications of the units using row numbers and references.

So why didn’t they flee? It could have been due to the dressing down by a colonel that Seebohm had received when the unit had previously pulled out of a position. Was it simply a matter of pride on the part of Seebohm?The colonel did not know the unit’s mission, but Seebohm vowed that it would not happen again. Any really safe position would not have been as effective an intercept position, either. Rommel was furious that the unit had been wiped out. The loss decimated the 621st. The equipment and men could be replaced, but they simply were not as experienced as the original intercept crews.

2Lt. Herz who was the 2 i/c proved to be extremely co-operative during his interrogation when discussing the appalling lack of radio secrecy and security by the British,. This laxity in wireless security was already well-known to the Allied intercept units but because of their own secret role they had been unable to reveal their source of the information and so unable to reveal the problem with any degree of credibility. Learning from the questioning of Herz, at last the British Army adopted the basic German procedure of using the Q code, tightening up on the use of R/T by officers, (the senior officers in particular having been guilty of a lack of security) and avoiding the abuse of low-grade codes such as ‘Codex’ by senior formations. One of the more memorable of Hertz’s remarks during interrogation was “We don’t have to bother much about ciphers, all we really need are linguists, the sort who were  waiters at the Dorchester before this war started”.

North Africa was an intercept-operator’s dream for both sides. The campaign’s mobility and fluidity necessitated widespread radio use and there were no landlines of any consequence. However, it was an extremely unhealthy environment in which to work. Sand flies drove everyone crazy and could cause infections. Many men got sick from their salty drinking water. There were sandstorms and relentless heat during the day and cold nights. Operational challenges abounded. They could not intercept or carry out direction-finding if its platoons were on the move. Yet, they had to be on the move in a campaign in which the front line was always changing – often rapidly. Seeboehm had to balance between intercept requirements and allowing communications with the intelligence evaluation centre, and what was safe for what was a support, not a combat, unit

The Germans were no slouches either, when it came to traffic analysis. Allied communications in the main were on the HF bands primarily in Morse code. Seeboehm had started out by having his operators scan the bands for unencrypted English traffic although some was enciphered. A radio network typically has a control station and a number of out stations. All traffic goes through control and for security reasons the out stations generally do not contact each other directly. Each station has a call sign, usually a code word. For instance, the coded call sign for the British 8th Army at one point was “MXQ.”

As the German intercept operators uncovered the various British radio nets, they had to determine what radio network they were listening to and its role. The British made their job much easier in mid-1941 through lax communications security before the capture of Seeboehm’s unit. They did not always use codewords. So a British radio operator might try and contact “8th Army” instead of MXQ so the Germans then knew what MXQ was. The British compounded the problem by not changing the various code words very often. There was also too much chatter on the British radio nets – gossiping really – and no real radio discipline. Another bad British habit was too much “cc’ing” of messages instead of simply leaving these addresses off of messages that did not directly concern them. From just one message, Seebohm could often learn all the out stations (subordinate units) to the control station (commanding unit). He could combine that with a captured codebook and/or good traffic analysis, and a British order of battle could be built up over time. Each Morse operator has a “fist” as unique as his voice. Seebohm’s intercept operators soon learned to recognize the British operators. The British typically failed to move their radio operators around, so each unit had a unique identifier. It did not matter if the unit’s coded call sign changed; the fist allowed the two to be linked. It would appear that the British were determined to make life as easy as possible for the Germans. The intercept operators passed along what they heard to the Company’s evaluation centre. German patience and thoroughness combined with British laxity and mistakes allowed the Company to put together the pieces of the puzzle of ‘who’ they were hearing and the traffic analysts began to create a British order of battle.

Lieutenant Wischmann’s team of cipher specialists now came into play to figure out what they were hearing. His team was co-located with the evaluation centres. German radio intercept companies did not normally have such specialists attached to them but the Afrika Corps was so far from the higher echelon intelligence centres that an exception was made to facilitate the decoding of British traffic.

‘Where’ the British units were was the job of the direction-finding platoon. The platoon’s elements were set up close to the front lines – absolutely vital if measurements were to be of any value with the battle taking place on such a narrow strip – and passed their results to the evaluation centre who then combined the results to determine the rough location of the intercepted call signs.

Amongst the many documents they had failed to destroy were past daily  and monthly reports, code names and code lists which were evaluated by Major Tozer’s staff at MI8 back in Cairo. They were translated and distributed by 30 July, only 20 days later, to all concerned with Allied wireless security, including the S O-in-C GHQ, India and the Signals instructor at the Staff College Quetta. Headed ‘German Wireless intercepts Organisation’ they included full details of the German war establishment, its system of working and the information derived from the interrogation of personnel, who were, in the main, reticent, as they had been trained to be with the exception, as previously mentioned, of the loquacious and forthcoming Lt Herz.

To say that the British High Command was amazed and flabbergasted by the vast array of intelligence that had been passed immediately to Gen. Rommel until then by the lax security and conversations on open radio links between GOC and the Corps Commanders and Chiefs of Staff, as if they had been talking on ‘secure hotlines’, using code-names for formations that were already known to Seebohm, would be the understatement of ALL TIME. Most of the intelligence was established by the almost complete lack of security in the conversations between the senior officers of the Imperial Forces according to Under-officer Fassy. His task had been made easier by such things as one officer asking for another officer to call him at a later (specified) time. When the communication was established it was then an easy matter, Fassy told his interrogator, to establish the identity of the units. There were a large number of captured R.T codes and code-names for units and formations. They had found it easy to take down verbatim, in English, conversations between the Army Commander and Corps Commanders which included operational orders. The British seemingly considered it sufficient camouflage to say, for example ‘the capital of England’ for LONDON. They would resort to Urdu and schoolboy French on occasions to camouflage their conversations. It was of little consolation that no copies of intercepted High Grade messages were captured. Urgent intercepted messages were sent to Rommel by radio and Wishmann claimed that Rommel was reading them while the British signals operators were still cracking the ‘received’ messages before sending them on to the addressee. This is perfectly believable since it has been claimed that some Enigma messages were being decoded and read before the German recipient. The evidence for this however is exceedingly slim based primarily on a request by Rommel for the repeat of a message that Bletchley had already received. On this occasion Rommel was seemingly giving himself time to avoid fulfilling an order from the Fuhrer.

What is salutary is that the history of Sigint in the 1914-18 conflict shows a similar disregard by the most senior of officers of security. Was nothing learned? Seemingly not as identical breaches of security were still being logged in BAOR in the ‘seventies’.

PWC Dec 2014