A number of German Shepherd dogs were dropped with the British Airborne Forces. Their acute hearing enabled them to give advance warning of incoming artillery rounds and they were also capable in some circumstances of sniffing out landmines. When not engaged in these tasks they were used for guard duties.
Glider Snatch Pick-up
In the first quarter of 1944 another, somewhat dubious, method of delivering stores was proposed. Maj R.F. Turner wrote to Brig Mockler-Ferryman, Director of London Group of SOE, advocating the use of gliders for the silent and possibly more accurate delivery of supplies. The gliders then available were designed for carrying troops or even a light tank and had to be towed by a twin-engined C47 Dakota aircraft or the much larger four-engined Halifax or Stirling bombers. Without troops the gliders could certainly have carried a substantial payload of arms and equipment but landing sites would have had to meet much more stringent criteria than those for parachuted supplies. Turner also saw the possibility of later pick-up of the glider if devices then under consideration could be developed sufficiently. The idea had several glaring disadvantages, chief of which were the cost, the depositing of another supernumary in enemy-occupied territory and the difficulty of transporting and hiding the glider till pick-up time.
The pick-up device then under consideration was originally intended for use with messages. Two masts were erected between which was strung a taut rope. Attached to this was a nylon rope fixed to a bag containing the items to be picked up. Torches would be laid out in a predetermined formation to guide the aircraft which would be trailing a rigid pole with a hook on the end. Capt Tice reported on a demonstration of the system at Station 61 on 26 July 1943 which must have shown some promise for a Lysander was modified for this work by 9 August. In fact, the system had already been used by Army Cooperation Command in the North Africa Campaign. But snatching up a message in a bag is a far cry from picking up a glider. To pick up a glider the ‘snatching’ aircraft must fly in extremely low, precluding the proximity of any trees or similar features which could afford cover for the waiting glider. Although the Americans developed a system for use with the C47 Dakota aircraft, it was not used widely and the SOE scheme appears not to have been pursued. When sporting gliding resumed after the war, the ‘snatch pick-up’ type of launch was strictly forbidden.
Human Pick-up
In 1944 SOE showed an interest in a technique developed at Wright Field in the USA for picking up a person from the ground by an aircraft flying overhead. A film of the trials in the USA using live sheep was shown at the War Office and reported upon by Everett. Despite an anticipated acceleration force of 10g and a 10 per cent casualty rate these trials had been completely successful, except for the loss of one sheep which had been strangled by its harness.12 Sacks and packages had also been picked up, but this was, in effect, an extension of the established Army Cooperation Command technique for picking up messages with a Lysander equipped with a trailing hook.
The person to be picked up was positioned in a suitable harness on the ground between two poles about 25 feet high. A long rope ran in a loop through the harness and across the tops of the poles. The aircraft – in the film a US twin-engined Stinson although an Avro Anson was also modified for this work – was fitted with a trailing hook and a means of winding into the aircraft the person snatched off the ground.
SOE subsequently arranged some trials using two human volunteers; an expert US parachute jumper and a British Commando Officer, Capt Lee-Warner. To get them used to the sensation they were first trailed behind the pick-up plane at a speed of 165 mph. For the actual pick-up the man would sit on the ground in his harness facing the oncoming aircraft and leaning back with his knees up to his chest. The aircraft would approach at 135 mph and had to climb away at 45 degrees immediately after the man was hooked to ensure he didn’t swing downwards after the initial acceleration and strike the ground or some obstruction. A recommendation was for the aircraft to have a safety device to cut the cord instead of hooking it should the run-in be found to be too low.
The man experienced a maximum G-force of 4.7 and accelerated to a speed faster than that of the aircraft, due, no doubt, to the elasticity of the shock absorbing devices. He was not wound in to the aircraft until he had stabilised on the trailing rope. Surprisingly, Capt Lee-Warner likened the discomfort to no worse than the jerk experienced when making a bad gear change on a motor cycle.
It was concluded that the pilot of the pick-up plane had to be 100 per cent accurate in speed, height and course of his run up and 100 per cent accurate in the timing of his climb after the snatch. Too early and the hook could miss the rope; too late and the man could be dragged along the ground. The sudden drag of the pick-up would tend to slow the plane, so the pilot had to be sure he had sufficient speed and power to avoid stalling as he entered the climb. It was further recommended that all parties have a knowledge of the equipment and that it should be used only in favourable weather. No records have been found of this technique being used during the Second World War although it was subsequently developed using C130 Hercules aircraft to pluck persons from the sea.
With the invasion of the European mainland only a few months away, the availability of aircraft for personnel and stores drops became critical. 138 and 161 Squadrons at Tempsford were assigned to drops on northern and north-western Europe but were equipped with only 23 Halifax aircraft, just sufficient to maintain an adequate number of drops to SOE’s existing circuits but certainly insufficient when the significant operational requirements of the Jedburgh teams was taken into account. Assistance was to come from the Americans who operated B24 Liberators for OSS in a similar manner from what they termed the ‘Carpetbagger’ base at RAF Harrington in Northamptonshire.
Despite the problems of air supply and the consequent occasional failure, there is no doubt that this route was the only way of maintaining supplies to the large number of Resistance groups in occupied territories. Improvements in the methods and equipment made it possible to increase the rate of supply from 1.5 tons (1527 kg) in 1941 to 28 tons (28,450 kg) in January/March 1943 and 277 tons (281,500 kg) in October/December 1943.
TWELVE
THE WIRELESS SECTION
An essential need of any secret organisation operating overseas is a clandestine means of communicating with its headquarters. In the mid-twentieth century diplomats had the ‘diplomatic bag’, generally agreed to be inviolable but not to be used for belligerent purposes. Embassies had their fixed wireless transceivers. But these facilities would not be available in time of war when embassies closed and friendly but neutral countries were unwilling to compromise their status by taking over the regular communications role. The normal postal mail service was, of course, nowhere near secure enough to be used for messages of national importance. What was needed was a rapid and secure (from interference by other parties) means of two-way communication.
Coded wireless transmissions in morse code had been established between the wars by SIS. The wireless sets provided then lacked three essential features for wartime clandestine use: range, portability and ease of concealment.
As the threat of war loomed SIS, which was using the 1936 vintage Mk XV wireless sets in their heavy wooden cases – by later standards huge – engaged a technical consultant in January 1939 to look into the requirements and availability of effective wireless communications. Shortly after, a small laboratory was set up at Bletchley Park where SIS, in the guise of the Government Code and Cipher School (GC&CS), had had its wireless headquarters since 1938. This unit was staffed by Capt (later Lt Col) E. Schroter MIEE, Royal Signals and two assistants. On the outbreak of war this embryonic section was moved to the newly requisitioned mansion at The Frythe. Hence the earliest wartime work carried out at The Frythe, even before SOE was set up in July 1940, included the development of means of clandestine communications.
Although the Wireless Section was one of the first (with part of Section D) to establish itself at Welwyn, it is rarely included in
the overall picture of events at Station IX and, indeed, has never been found on an organisational chart of SOE’s Research and Development Section. This can be explained at least in part by the fact that in the early days of SOE, even after Section D had been absorbed into it, the new organisation was dependent for its signals work on Section VIII of SIS. This dependence extended to the provision of the unsatisfactory Mk XV wireless sets.
So when Prof Newitt was appointed Director of Scientific Research at the beginning of 1941 his remit did not include the Wireless Section which remained under the Chief Signals Officer. In due course SOE became independent of SIS, establishing its own receiving stations at Grendon Underwood and Poundon near Bicester. As recorded here, the Radio Communications Division as it came to be known, moved away from Station IX in the middle of the war and was split between accommodation at a number of factories mainly to the north of London. Theirs was a vital contribution to the operation of SOE and its research and development work should be included here.
The Wireless Section, or RCD, carried out a great deal of research and development work on the wireless transceivers (instruments which can both transmit and receive signals) – and also on navigational aids to assist pilots in locating drop zones and on devices for the recharging of the power sources for agents’ sets. These power sources (accumulators) were normally similar to the car batteries of the day – heavily constructed of glass. To be recharged they required an input of electrical current for several hours; a suitable mains electrical supply was rarely available in the remoter areas of SOE’s theatres of operations.
THE ‘S’-PHONE
One of the earliest projects of the Wireless Section was conceived in the Western Highlands of Scotland. A Royal Signals instructor, Sgt (later Maj) R.C. Bryant, was working at Loch Ailart under Maj (later Col) F.T. Davies using a small microwave radio-telephone (R/T) set for operation in hilly country, where considerable line-of-sight ranges were possible between hilltops. It occurred to Davies that this form of wireless would be ideally suited for ground-to-air communication with aircraft. Trials were arranged at Renfrew airfield near Glasgow in October 1940 under Capt (later Col) J.W. Munn, RA and were sufficiently promising for the development of the idea to be given to the small research team at what was now SOE’s Station IX. This was the start of development of the highly successful ‘S’ phone which eventually enabled a reception committee to ‘talk down’ an incoming Lysander or Hudson aircraft delivering and picking up agents in occupied territory.
The S-Phone was a development of an ultra-high-frequency portable R/T which both civilians and the military had been working on before the war. It came in two parts: the bulky section in the aircraft or ship and the other part being self-contained and carried easily by the operator on webbing braces on his body. Shoulder straps held the set with its directional aerial in front on the chest while a waistbelt held seven canvas pouches: five containing miniature batteries, the others being storage for earphones, microphone, aerial and vibrator power pack. The set transmitted over 337 megacycles and received on 380 megacycles but no switching was required between reception and voice transmission, a very significant advantage for the aircraft reception work SOE had in mind. The power output was only 0.1 to 0.2 watts so the range of communication was limited to about forty miles if an aircraft was at 10,000 feet and about six miles when it was down to 500 feet. Interception by the enemy was hardly possible on the ground. The microphone was shielded so that voice communication was very clear, it being possible to recognise an operator’s voice and hence sometimes to check on the security of the reception committee, but nothing could be heard alongside the user.
A story has it that during a visit to Station IX, Brig Orde Wingate, the Chindit leader who fought the Japanese in Burma so successfully using unorthodox techniques, is reputed to have heard German being spoken from within a shrubbery. He drew a knife and approached stealthily, thinking enemy agents might have somehow infiltrated the guarded site. He pounced on a man in a trench speaking into a radio before handing him over to a guard who recognised the man as a member of staff who was conducting tests with the ‘S’-phone by talking to a colleague in another slit trench in the language common to Hungarian and Norwegian operators.
Even if the principle of this instrument had been originally designed by another agency for other purposes, it was certainly developed and modified to great effect at Station IX. The S-phone proved to be of immense value to the reception committees attempting to guide aircraft to landing fields under a full, or nearly full, moon. One disadvantage of the set was that it was difficult to conceal and impossible to pass off as anything else during a spot check by the Germans.
REBECCA/EUREKA
Another navigational aid was the mobile Rebecca/Eureka radar device invented by the Telecommunications Research Establishment (TRE), a much bulkier apparatus than the S-phone. Rebecca was the airborne component permanently fixed in the aircraft; Eureka was in essence a radar beacon which was set up in the DZ and was coded to respond only to a prearranged signal from Rebecca which would contact it initially when some 70 miles away. With proper use an aircraft could be guided to within 200 yards of its DZ. Both the ground beacon and the airborne portion were fitted with self-destruct devices should unauthorised examination be attempted.
The use of Rebecca/Eureka for clandestine landings was not popular among resisters due to the bulk of the equipment. Eureka weighed almost 112 lb (50 kg), was barely portable and impossible to conceal adequately. The Special Duties Squadrons of the RAF, however, recognised its value to them and tried unsuccessfully to persuade reception committees to simplify the operation by the use of the Eureka grid. The device was, however, used extensively in British and US airborne landings in 1944– 45.
By September 1941 the Wireless Section was commanded by Maj H. Pickard and had expanded in response to demand to an establishment of 40 persons, some working on the ground set of the ‘S’ phone, while others were exploring the problems of wireless communication between agents on the European mainland and receiving stations in England. It has to be realised that at this time there was no proprietary commercial or service equipment available to communicate 150– 800 miles round the clock and throughout the year, which was what SOE needed. SOE Signals were still frustratingly under the control of SIS, who provided wireless sets such as the Mk XV. By the end of 1941 it was clear that this presented serious problems. Not only was the older organisation able to read the other’s traffic, but it also controlled the numbers and types of wireless sets sent to SOE’s agents. Efforts to separate the two signals operations had been initiated by SOE before Col G. Ozanne was appointed Chief Signals Officer in February 1942 and started looking to the future. The following month the Chief of the Secret Service (CSS) unexpectedly agreed to SOE’s independence but it was not until June that its first wireless station at Grendon Underwood near Bicester began to transmit. Now SOE was in a position to design and develop its own wireless sets in the small section at Station IX.
It is perhaps worth dwelling for a moment on the sets allocated to SOE by SIS up to the time of their separation.
The Mark XV Wireless Set
Even before the outbreak of hostilities SIS depended for its wireless communications with its agents on the Mk XV set which consisted of a separate transmitter and receiver, each bulky, heavy and far from ideal for a clandestine operation. The two-valve transmitter in its varnished plywood case and its three-valve receiver were of similar size and weighed 45 lb (20 kg). Carrying these items without drawing attention to them was clearly no joke. But at least their 20 watts power output was more than adequate. The transmitter covered frequencies from 3.5 to 16 megacycles in three bands and included a power pack for use with either a domestic mains supply or a six-volt battery, the latter being contained in a heavy metal box. The morse key was built into the face of the unit. Its associated receiver covered three to thirteen megacycles in one waveband and had a fine-tuning dial with a frequency range of 200
kilocycles on either side of the frequency displayed on the main dial.
The Paraset
SIS next provided a few Parasets, relatively simple and compact transceivers housed in steel boxes. The transceiver weighed only 3½ lb (1.6 kg) and the power pack 7 lb (3.2 kg). The receiver covered 3– 7.6 megacycles in one waveband while the transmitter had two wavebands covering 3.3– 4.5 and 4.5– 7.6 megacycles. The power output was about five watts. The sets suffered from a number of shortcomings, not least of which was the ability to interfere with any other wireless set within a hundred yards radius, a fault which did not endear them to agents in built-up areas where they could attract the attention of German listening detectors.
STAFFING THE SECTION
One may wonder how such a small, obscure and secretive establishment recruited the highly skilled personnel necessary to staff its laboratories and workshops. The answer seems to be that word got around, in the case of John Brown among officers concerned with wireless communications. His imaginative skills became apparent early in his military career and spawned a number of extremely successful wireless sets. One of the longest-serving and most talented radio technicians to work at Station IX, Sec Lt (later Maj) John Isaac Brown had lived in the Finsbury Park district of London and from the age of eleven was interested in anything electrical. He subscribed to Wireless World (price 4d) and learned enough to take over a kit-built wireless set which a friend had failed to make operational, check through it methodically, find the fault and make it work. When he left school he took his wireless set to the firm of Scott-Sessions in Muswell Hill seeking a job. This firm made custom built wireless sets and were sufficiently impressed to take him on as a junior apprentice. Here he was encouraged to ask questions while in the evenings he attended the Regent Street Polytechnic and Northern Polytechnic colleges to further his theoretical technical education.
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