Editing Double-Cross System (section)

{{Short description|British counter-espionage and deception operation of WW2}}
{{more citations needed|date=March 2018}}
The '''Double-Cross System''' or '''XX System''' was a [[World War II]] [[counter-espionage]] and deception operation of the British Security Service ([[MI5]]). [[Nazism|Nazi]] agents in Britain – real and false – were captured, turned themselves in or simply announced themselves, and were then used by the British to broadcast mainly [[disinformation]] to their Nazi controllers. Its operations were overseen by the '''Twenty Committee''' under the chairmanship of [[John Cecil Masterman]]; the name of the committee comes from the number 20 in [[Roman numerals]]: "XX" (i.e. a double cross).

The policy of MI5 during the war was initially to use the system for [[counter-espionage]]. It was only later that its potential for deception purposes was realised. Of the agents from the German intelligence services, ''[[Abwehr]]'' and ''[[Sicherheitsdienst]]'' (SD), while many who reached British shores turned themselves in to the authorities, others were apprehended after they made elementary mistakes during their operations. In addition, some were false agents who had tricked the Germans into believing they would spy for them if they helped them reach England (e.g., [[Nathalie Sergueiew|Treasure]], [[Roger Grosjean|Fido]]). 

Later agents were instructed to contact agents who, unknown to the Abwehr, were controlled by the British. The Abwehr and SD sent agents over by parachute drop, submarine, or travel via neutral countries. The last route was most commonly used, with agents often impersonating refugees. After the war, it was discovered that all the agents Germany sent to Britain had given themselves up or had been captured, with the possible exception of [[Jan Willem Ter Braak|one who committed suicide]].<ref name=Masterman/>