Funkspiel

"Funkspiel" ("radio play") was the name given to a counter-espionage operation carried out by German counter-intelligence during the Second World War. It consisted of using captured and returned clandestine radio operators in France to send false messages back to the enemy (the United Kingdom in particular), and allowed the German services to intercept Allied military information, transmit disinformation to the enemy and to fight resistance movements. So, the German counter-intelligence "played" to be a resistance movement, with a script for the piece written by the Gestapo or the Abwehr.

The last faked message that the Germans would have exchanged with London in this operation was this: "Thank you for your collaboration and for the weapons that you sent us". However, the Germans did not know that the British intelligence services had realised the truth of the German stratagem at least two weeks before this transmission. Thus, if the Germans had been able to gain certain benefits from the operation, the strategy was later used against them and from May 1944 onwards the operation was no longer a success.

Source

*Jacques Delarue, "Histoire de la Gestapo", Paris, Fayard, 1962, p. 521-523.