Operation Fortitude was a military deception operation by the Allied nations as part of Operation Bodyguard, an overall deception strategy during the buildup to the 1944 Normandy landings. Fortitude was divided into two subplans, North and South, and had the aim of misleading the German High Command as to the location of the invasion.
Fortitude had evolved from plans submitted by Noel Wild, the head of Ops (B), and John Bevan, from the London Controlling Section in late 1943. Early revisions in January 1944 suggested a fictional buildup of troops in southern England with the hope of drawing German attention to Pas-de-Calais. Colonel David Strangeways, head of Bernard Montgomery's R Force deception staff, was unimpressed with the approach. He was widely critical of the original plan and eventually rewrote the Fortitude deception with a focus on creating a more realistic threat.
Both Fortitude plans involved the creation of phantom field armies (based in Edinburgh and southern England), which threatened Norway (Fortitude North) and Pas de Calais (Fortitude South). The operation was intended to divert Axis attention away from Normandy and, after the invasion on 6 June 1944, to delay reinforcement by convincing the Germans that the landings had been purely a diversionary attack.
Background
Fortitude was one of the major elements of Operation Bodyguard, the overall Allied deception stratagem for the Normandy landings. Bodyguard's main objectives were to ensure that the Germans would not increase troop presence in Normandy and to do so by promoting the appearance that the Allies would attack in other locations. It consisted of a wide range of deceptions ranging across the European front, with Operation Fortitude representing the main effort to misdirect the Oberkommando der Wehrmacht (German High Command) to believe in specific mainland invasion objectives.
The problem facing the Allies was that France was the most logical choice for an invasion into German-occupied Europe. Therefore, the Allied high command had only a small geographical area across which to mislead the German defences. Montgomery, commanding 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 37 divisions at his command, compared to around 60 German Army formations. That meant that any deception would have to convince the German high command that the Allies were not committing their full forces into Normandy, but holding many of those formations in reserve.
Operation Fortitude focused on creating invasion threats from the United Kingdom into various parts of Western Europe. The plan was eventually split into two parts, North and South. Fortitude South focused on creating confusion about the Allied Channel crossing, and Fortitude North, staged out of Scotland, introduced a threat to occupied Norway.
A deception of such a size required significant organisation and input from many organisations, including MI5, MI6, SHAEF via Ops B, and the armed services. Information from the various deception agencies was organised by and channelled through the London Controlling Section. To help keep the approach well-organised, Strangeways divided the implementation stages into six subplans, codenamed Quicksilver.
During a similar operation in 1943, Operation Tindall, a fictional field army (British Fourth Army) had been created, headquartered in Edinburgh Castle. It was decided to continue to use the same force during Fortitude. Unlike its southern counterpart, the deception relied primarily on fake radio traffic since it was judged unlikely that German reconnaissance planes could reach Scotland without being intercepted. False information about the arrival of troops in the area was reported by the double agents Mutt and Jeff, who had surrendered after their 1941 landing in the Moray Firth, and the British media co-operated by broadcasting fake information, such as football scores or wedding announcements, to nonexistent troops. Fortitude North was so successful that by late spring 1944, Hitler had positioned 13 army divisions in Norway.
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 and military outposts. That coincided with an increase in naval activity in the northern seas and in political pressure on neutral Sweden.
After invasion
On 20 July, Ops (B) took over control of Fortitude South from R Force. The previous month, it had begun work to follow up the operation.
Through the evolved plan, the Allies maintained the pretense of FUSAG and other forces threatening Pas-de-Calais for some considerable time after D-Day, possibly even as late as September 1944. That was vital to the success of the Allied plan by forcing the Germans to keep most of their reserves bottled up in wait for an attack on Calais that never came. That allowed the Allies to maintain and to build upon their foothold in Normandy. He added that he expected the Allies would then attack in force across the Strait of Dover.
Overall, Fortitude was successful for several reasons:
- The long-term view taken by British Intelligence to cultivate double agents as channels of disinformation to the enemy.
- The use of Ultra decrypts of machine-encrypted messages between the Abwehr and the German High Command, which quickly indicated the effectiveness of deception tactics. That is one of the early uses of a closed-loop deception system. The messages were usually encrypted by Fish, rather than Enigma machines.
- Reginald Victor Jones, the Assistant Director Intelligence (Science) at the British Air Ministry, insisted that for reasons of tactical deception, for every radar station attacked within the real invasion area, two were to be attacked outside it.
- The extensive nature of the German intelligence machinery and the rivalry among the various elements.
- General George Patton was the leader whom the Germans feared the most, and they considered him the Allies' best general. The lawsuit would be settled in March 2024.