Operation Copperhead Operation Copperhead was a small military deception operation run by the British during the Second World War . It formed part of Operation Bodyguard , the cover plan for the invasion of Normandy in 1944 , and was intended to mislead German intelligence as to the location of General Bernard Montgomery . The operation was conceived by Dudley Clarke in early 1944 after he watched the film " Five Graves to Cairo " . The German high command expected Montgomery , one of the best - known Allied commanders , to play a key role in any cross - channel bridgehead . Clarke and the other deception planners reasoned that a high - profile appearance outside England would suggest that an Allied invasion was not imminent . An appropriate look - alike was found , M . E . Clifton James , who spent a short time with Montgomery to familiarise himself with the general ' s mannerisms . On 26 May 1944 , James flew first to Gibraltar and then to Algiers , making appearances where the Allies knew German intelligence agents would spot him . He then flew secretly to Cairo and remained in hiding until Montgomery ' s public appearance in Normandy following the invasion . The operation did not appear to have any significant impact on German plans and was not reported high up the chain of command . It was executed some time before D - Day , and in the midst of several other Allied deceptions . German intelligence might have suspected a trick , or not attributed much importance to the visit . Following the war James wrote a book about the operation , " I Was Monty ' s Double " . It was later adapted into a film , with James in the lead role . Background . In preparation for the 1944 invasion of Normandy , the Allied nations conducted a complex series of deceptions under the codename Bodyguard . The overall aim of the plan was to confuse the German high command as to the exact location and timing of the invasion . Significant time was spent constructing a notional army , the First United States Army Group , to threaten Pas de Calais , as well as political and visual deceptions to communicate a fictional Allied battle plan . Copperhead was a small portion of the overall Bodyguard plan , conceived by Dudley Clarke . Earlier in the war , Clarke had pioneered the idea of strategic deception , forming a deception department in Cairo named ' A ' Force . Clarke and ' A ' Force were not officially in charge of Bodyguard planning ( a role that fell to the London Controlling Section ) , but because of the location of the deception the Cairo planners organised much of the operation . On a visit to Naples in January 1944 Clarke had seen the film " Five Graves to Cairo " , in which actor Miles Mander makes a brief appearance as Bernard Montgomery . The film involves one character impersonating another ; Clarke suggested attempting the same trick in real life . He proposed an operation to mislead German commanders as to Montgomery ' s location in the days immediately before the Normandy landings , codenamed Operation Neptune . Montgomery was one of the most prominent Allied commanders , and the German high command expected him to be present for any invasion of France . Clarke hoped his apparent presence in Gibraltar and Africa would lend support to the idea that the Allies might be planning landings in Southern France as part of Operation Vendetta , rather than across the Channel . While in London in February , Clarke , along with the London Controlling Section and Ops ( B ) , drafted Copperhead in support of Vendetta . Operation . Mander , the actor from " Five Graves to Cairo " , was located in Hollywood but found to be too tall in real life . A second look - alike was found , but soon afterwards was injured in an accident . Eventually , Lieutenant - Colonel J . V . B . Jervis - Reid , head of Ops ( B ) , spotted a photograph of Meyrick Clifton James in the " News Chronicle " . James , an Australian , had spent 25 years as an actor before the war , and at the time was assigned to the Royal Army Pay Corps . Colonel David Niven , a well - known British actor , was asked to contact James and offer him a screen test for future army films . When he arrived at the meeting , James was told his true role . James was not a perfect stand - in for Montgomery . He had lost a finger during the First World War , so a prosthetic had to be made . He had also never flown before , so the London Controlling Section ' s Dennis Wheatley took James up for a test flight to make sure he did not suffer from air sickness . Finally , James both drank heavily and smoked cigars , while Montgomery was a teetotaler and disliked smoking . The deceivers were worried that James might be spotted drinking , spoiling the performance . Despite these hitches , and with Montgomery ' s approval , the plan went forward . To get into character , James spent some time with the general , posing as a journalist , to study his mannerisms . Allied deceivers used their double agent network to circulate the idea that Montgomery would command ground forces during the invasion . Then , on 26 May 1944 , James flew overnight from RAF Northolt to Gibraltar , where the Germans maintained an observation post overlooking the airport from across the Spanish border . The plane had to circle for an hour before landing to allow James , who had smuggled a bottle of gin onto the flight , to sober up . He then attended breakfast with the British governor , Sir Ralph Eastwood , before departing again for the airfield . The Allies had arranged for Ignacio Molina Pérez , a Spanish envoy known to be a German spy , to visit Government House . After observing James ' s departure , Pérez hurriedly crossed the border to place a call to his German handler . James then flew to Algiers , where he was publicly paraded through the airport and driven to meet General Maitland Wilson , ostensibly for a meeting to discuss operations against the south of France . Instead , he was moved quietly to a remote villa by ' A ' Force ' s Rex Hamer . Rumours suggest this was because James had been spotted smoking and staggering around Algiers , so the deceivers decided to cut his appearances short . Whatever the reason , the next day , out of character , James was flown to Cairo . He was to remain hidden there until the public disclosure of Montgomery ' s presence in France . Meanwhile , double agents in North Africa were used to extend the masquerade for a few more days , by hinting Montgomery was still in the region . Impact . The precise impact of Copperhead is unclear . The visit was reported up the German chain of command , and some double agents later received requests for information about Montgomery ' s movements . However , there is no indication that Montgomery ' s appearance affected German views of the imminent invasion threat . Writing in 2011 , Joshua Levine attributes this to the fact that the deception was carried out some ten days before D - Day , arguing that there would be no reason for a flying visit to North Africa to preclude an imminent invasion . Another factor was that , in early May 1944 , an uncontrolled agent based in Spain ( who sold fictional intelligence to the Germans ) had passed on details of a meeting in Gibraltar between several high - ranking Allied officers . Documents found after the war indicated the Germans found this information suspect , and that they might have treated Montgomery ' s appearance as equally so . Although double agents received a number of urgent requests from the Abwehr about Montgomery ' s whereabouts it does not appear that this information was passed on to the German commanders in France . The Bodyguard deception had successfully created confusion within German command as to Allied intentions , and the appearance of Montgomery in Gibraltar added little to the picture . James did not enjoy the experience . Although he received equivalent pay ( £10 per day ) to Montgomery during the operation , it was a high - pressure assignment . Following Montgomery ' s public appearance on the Normandy beachhead , James was flown back to England and resumed his role within the Pay Corps . He was also warned not to discuss the operation . Dennis Wheatley , in his memoirs , commented that he felt James had been treated " shabbily " for his efforts . Later depictions . In 1954 James wrote an account of the operation , entitled " I Was Monty ' s Double " ( published in the United States as " The Counterfeit General " ) . The British government made no attempt to stop publication , and in 1958 the book was adapted into a film of the same name . James starred , both as himself and Montgomery , alongside John Mills , as an intelligence agent .