Although the Germans knew an Allied invasion of north-west Europe was going to come - it was critical that the key details of exactly when and where remained a complete surprise. By 1943 Hitler was defending the entire European western coast, with no clear knowledge of where the Allied invasion would take place. The German tactic was to defend the entire length of the coastline whilst relying on reinforcements to quickly respond to any landings. A series of plans designed to confuse and mislead the German High Command was devised, under the broad scheme known as Operation Bodyguard.
The Allies had already mounted successful deception operations against the Germans. One notable action, codenamed Mincemeat, involved releasing a dead body from a submarine that would surface just off the Spanish coast. The aim was that the body would drift to shore on the tide, appearing to be a military passenger from a downed Allied aircraft. Dressed as an officer of the Royal Marines, personal items were planted on the body and a briefcase containing faked documents secured to its wrist. The documents were in the form of correspondence between two British generals which suggested that the Allies planned to invade Greece and Sardinia, with Sicily - the Allies' real objective - being just the target of a diversionary assault.
The design of the operation called for the body to be recovered by the Spanish. Although Spain was supposedly neutral, the British believed that representatives of the Abwehr, the German military intelligence organisation, would be informed of the discovery and the documents shared with them. The Spanish did discover the body and the documents and effects were subsequently returned to the Vice-Consul Francis Haselden. Following a forensic examination back in England, it was established that they had been read, and later decrypts of German communications suggested that the Germans had been fooled. German reinforcements were shifted to Greece and Sardinia both before and during the invasion of Sicily, whilst Sicily itself received none.
In wartime, truth is so precious that she should always be attended by a bodyguard of lies.
Planning for Bodyguard started in 1943 and a draft strategy, referred to as Plan Jael, was presented to Allied High Command at the Tehran Conference in November, before finally being approved on Christmas Day. The objectives of the operation were to deceive the enemy as to the timing, scale and direction of the Allied invasion in France. Its three main goals were to: make the Pas de Calais appear to be the main invasion target; to mask the actual date and time of the assault and to keep German reinforcements in Pas de Calais (and other parts of Europe) for at least two weeks following the actual landings.
The overall Bodyguard plan entailed numerous sub-operations. The largest of these was Operation Fortitude - itself split into two. Fortitude North was intended to convince the German high command that the Allies, staging out of Scotland, would attempt an invasion of occupied Norway. Fortitude South, meanwhile, had the intention of presenting the Pas de Calais area as the objective - sometime in mid-July - as it was likely that Germans reconnaissance would successfully discover invasion preparations in the South of England. Following the real landings in Normandy, six fictional divisions would keep this threat to the Calais area alive.
A key element of Fortitude South was Operation Quicksilver. It entailed the creation of the belief in German minds that the Allied force consisted of two army groups, 21st Army Group under Montgomery (the genuine Normandy invasion force), and 1st U.S. Army Group (FUSAG) (a fictitious force under General George Patton), positioned in south eastern England for a crossing at the Pas de Calais. FUSAG was a skeleton formation formed for administrative purposes, but never used. However, the Germans had discovered its existence through radio intercepts.
General Montgomery, the commander of the Allied landing forces, knew that the crucial aspect of any invasion was the ability to enlarge a beachhead into a full front. He also had only limited divisions at his command - just 37 compared to around 60 German formations. Fortitude South was key to giving the impression of a much larger invasion force in the South-East of England, to achieve tactical surprise in the Normandy landings and, once the invasion had occurred, to mislead the Germans into thinking it a diversionary tactic with Calais the real objective.
To "sell" this deception to the Germans, the set-building staff from film studios and theatres were hired and transported to Kent to help build the fake army. Numerous buildings were constructed whilst inflatable trucks and tanks, dummy aircraft and fake landing craft were positioned around possible embarkation points. General Patton was photographed visiting many of these sites.
One clever piece of misinformation was inadvertently supplied by a Panzer officer. The badly injured POW was being returned to Germany and thought he was traveling through Kent and witnessing the Allied military build-up in the east of England. In fact, he was being driven through Hampshire, and was actually seeing parts of the invasion force destined for Normandy. At his debriefing upon returning home, has was able to provide credence to the other intelligence estimated the Germans had developed.
German aerial reconnaissance capabilities, however, were overestimated by the Allies, and the physical deception methods using "spoofs" - such as rubber tanks - were of far less significance than other methods. Of far more importance was a huge amount of false radio traffic generated intended to simulate routine communications between different units.
Perhaps the most importance tactics employed in Operation Fortitude was the use of the Double Cross system. MI5's counter-intelligence operatives had been very successful in managing to identify all of the German agents in Britain - and in many cases turning them into double agents. Those agents that had been "turned" were being used to feed Hitler's commanders false information. The most notable double agent was not a "turned" German spy at all but rather an eccentric Spaniard name Juan Pujol García. He had presented himself to the Germans offering to spy for them - but then approached the British offering to act as a double agent for them. Although rejected at first, MI5 eventually agreed to use him and moved Pujol and his wife to England.
Through his MI5 handlers he created a network of fictional contacts who "reported" information to him which he duly passed on to the Nazis. Codenamed Garbo by the British, and Alaric Arabel to the Germans, Pujol's reports to his German contacts were treated with such high confidence that he was actually awarded the Iron Cross for his services to the Reich. He eventually operated a network of some 27 agents across the UK, all of them works of imagination.
In January 1944, the Germans told Pujol that a large-scale invasion of Europe was likely to be imminent. He sent over 500 radio messages between January 1944 and D-Day, at times more than twenty messages per day. In order to maintain his credibility, it was decided that GARBO, through one of his agents, should give some forewarning of the actual invasion, albeit transmitting the details too late for the Germans to take effective action.
Arrangements were made with the German radio operators to be listening to GARBO during the night of 5/6 June 1944, under the guise that one of the fictitious sub-agents was due to appear with some important information. At 03:00hrs, Pujol's transmission went unanswered until 08:00hrs. In colourful terms, Pujol expressed his disgust at their "negligence". However, due to the later-than-planned timing of his transmission he was also able to add more operational details to his report, which simply added to his credibility and value in the eyes of the Germans.
I think that diversionary actions will take place in a number of places - against Norway, Denmark, the southern part of western France, and the French Mediterranean coast. After that, when they have established bridgeheads in Normandy and Brittany and have sized up their prospects - they will then come forward with an all-out second front across the Straits of Dover.
Fortitude North was designed with the intention of misleading the Germans into believing an invasion of Norway was going to take place. The Allies hoped that the threat to the weaker defences in Norway would prevent or delay the reinforcement of German forces in France following the Normandy landings. The plan involved simulating a build-up of forces in northern England and political contact with Sweden.
The Allies felt that Scotland was out of range for German aerial reconnaissance - at least without being intercepted first - so Fortitude North relied more heavily on fake wireless transmissions and false information passed through double agents. Even the British media cooperated by broadcasting fake information to the non-existent troops, including football scores and wedding announcements.
In the early spring of 1944, British commandos attacked targets in Norway to simulate preparations for invasion. They destroyed industrial targets, such as shipping and power infrastructure, as well as military outposts. This coincided with an increase in naval activity in the northern seas, and political pressure on neutral Sweden.
Operation Skye was the codename given to the radio deception component of Fortitude North. It is not possible to tell what impact the operation had on the Germans as there is no evidence they were even monitoring the transmissions emanating from Scotland, however, by late spring 1944, Hitler had thirteen army divisions stationed in Norway. Every soldier in Norway was one fewer available to resist the Allied invasion of Normandy. Following the D-Day landings, Hitler delayed moving reinforcements from the Pas de Calais to Normandy for almost seven weeks.
During the course of the operation, but lack of German aerial reconnaissance along with the absence of uncontrolled German agents in Britain rendered the physical deception tactics almost irrelevant. The use of German double agents proved to have the most impact. A post-war examination of German records found that during Operation Fortitude no fewer than sixty-two of Agent GARBO's reports were included in German Armed Forces High Command (OKW) intelligence summaries.
By the end of September 1944 the Allies had agreed to end the Fortitude deception, moving entirely to operational deceptions in the field through the use of dedicated tactical deception units. The 23rd Headquarters Special Troops, known as the "Ghost Army", were an American unit that carried on deception operations in Normandy and for the remainder of the war in Europe, using visual, sonic, radio and atmposhperic deception.