As with all countries under German occupation, in France the Abwehr (German Military Intelligence) and the Gestapo employed huge resources to track down wireless operators. Apart from resistance movements being unable to function without arms, explosives and other support which could only be obtained through wireless links to London, Hugo Bleicher who was a senior non-commissioned officer with the Abwehr and responsible for crushing resistance in France, said they regarded wireless operators as a rich source of intelligence because they had knowledge of every message and orders received from London.
The headquarters of the French Section in London were aware of the dangers facing their agents and those volunteering for wireless training were told their chances of survival, with a bit of luck, was six-weeks and if captured they would very likely be tortured by the Gestapo for their personal codes which could be used by a German operator to ‘play-back’ their wireless to London. Only later did the section become aware ‘play-back’ had been used by the Germans with great success in the Netherlands and many agents along with members of the resistance had been killed or transported to concentration camps where they were later executed. (information about the Dutch section will found at the link provided)
Jacqueline Nearne, former courier with SOE French seen in the public information film ‘School for Danger: Now the truth can be told’ which was produced after the war.
Agents volunteering for wireless duties were sent on a technically challenging course at the Wireless and Security School and the two main establishments were located at Fawley Court in Henley-on-Thames and Thames House in Oxfordshire. Apart from learning to send and receive Morse Code at a sufficient speed they needed to understand radio wave propagation, the use of cyphers and learn how to repair their wireless in the field. They also needed to prove their competence in the use of various security measures intended to make it difficult for German direction finders pin-pointing the safe houses they were using whilst in contact with London.
A recent photograph of Fawley Court
When wireless trained agents arrived in France their first task was to find several suitable locations from which to use their transmitter to pass messages to London as quickly as possible whilst ensuring they never stayed on the air for over twenty-minutes, but for a variety of reasons some operators broke the twenty-minute rule and did not survive the war.
It was not long before the Germans introduced radio jammers which apart from making it difficult to send and receive messages was also intended to force operators to remain longer on the air to pass messages.
Information about the Wireless War against SOE D Section (Dutch)