On 6 June 1944, Allied forces invaded German-occupied France and began liberating mainland Europe from Nazi Germany.
The Normandy landings, also known as Operation Neptune, took months of careful planning and resulted in the largest single-day amphibious invasion in history.
However, while many know about the incredible sacrifice made by troops on D-Day, a lesser-known part of history is what led up to that important day.
Crucial deception plans were key to the success of the D-Day landings and in the Allies' victory over Germany during the Second World War.
Operation Bodyguard was approved at the end of 1943 and it culminated six months later, with the success of the D-Day landings.
Inflatable hardware, as part of Operation Fortitude, was a key element of Bodyguard – the plan to fool Nazi Germany.
A necessary operation
In December 1943, British Prime Minister Winston Churchill, US President Franklin D. Roosevelt and Soviet Premier Joseph Stalin met in Tehran for a conference.
The conference, code-named 'Eureka', was a strategy meeting to discuss the next steps in the battle against Nazi Germany.
During the meeting, the three leaders committed to a plan to attempt to defeat Germany and Japan.
Part of the plan was Operation Overlord – the invasion of German-occupied northern France in what became known as the D-Day landings on 6 June 1944.
As soon as it was decided that the first step was to free Normandy, creating a strategic entry point to the continent, Allied Forces understood the importance of a deception plan.
The decoy plan was code-named Operation Bodyguard and it was one of the many parts of the broader Operation Neptune.
Distracting the enemy
Once the Allies decided the Normandy would be the best place to invade Germany-controlled France, it was necessary to minimise the number of German troops able to counteract the attack.
Before D-Day, Nazi troops controlled the so-called 'Atlantikwall' – a series of coastal defences which extended from Norway to France.
They were strategically placed by the Nazis to defeat any attack coming from the sea.
Operation Bodyguard was aimed at distracting Germany and shifting attention from the coast of northern France to other parts of Nazi territory.
An intricate series of deception operations was put into action 45 days ahead of D-Day, scattering misinformation and doubt behind enemy lines.
Deception on the Western Front
One of the more delicate aspects of the plan was to distract Nazi troops on the Western Front of the territory they controlled, as that was precisely where the landings were going to take place.
Germany already suspected that any Allied attempt at invasion would take place on the French coast and Pas de Calais, the Nazi-controlled territory closest to England, appeared to be the most likely target.
Ultimately, the aim was for the Allies to make Germany believe they were about to strike at the same time in both France at Pas de Calais and in Norway, shifting their attention away from the shores of Normandy.
This part of the plan, which also used inflatable tanks pointing towards Nazi-controlled territories, was called Operation Fortitude.
Meanwhile, a second operation was also in motion to deceive Germany into thinking another attack could be taking place in France.
Operation Ironside did not make use of any type of physical deception like the fake tanks used during Operation Fortitude – instead, it relied purely on controlled misinformation.
Double agents were given the task of confusing the Germans between May and June 1944, passing the message that the Allied block was planning an attack near Bordeaux, along the Bay of Biscay.
Again, the aim was to deflect German assets and attention away from Normandy.
Deception in the Mediterranean
Two more deception operations took place far from French beaches between February and July 1944.
Operation Zeppelin was the equivalent of Operation Fortitude, but with fictitious targets in Mediterranean countries.
The idea was to make Germany believe the British Army was preparing an amphibious operation from North Africa to the Balkans while they received support from Soviet troops, focussing Nazi attention away from Normandy and towards areas that the Allies had no intention of invading yet.
It is still unclear whether German commanders believed there would be a full-scale landing in the Mediterranean, but the key achievement of the deception was that Nazi Germany overestimated the size of Allied military assets.
A few days before D-Day, a further operation was launched in the Mediterranean - Operation Copperhead.
One of the best-known Allied commanders, General Bernard Montgomery, was expected to play a crucial role in any decision to cross the English Channel by the German forces.
In May 1944, an Australian-born look-alike of General Montgomery was flown to the Mediterranean and spent the next few days touring Gibraltar, Algiers and other locations where German intelligence was expected to spot him.
The Allies believed that if the Germans saw Gen Montgomery in the Mediterranean, they would focus their attention on southern Europe.
Game-changer inflatable tanks
The contribution of Operation Zeppelin and Operation Copperhead to the success of the D-Day landings is uncertain but many believe that Operation Fortitude was a game-changer.
Fortitude was crucial in ensuring German reserves were delayed in responding to the situation unfolding on the shores of Normandy on 6 June 1944.
Decoy equipment, including inflatable tanks, timber-and-rubber landing crafts and mock aircrafts replaced real vehicles, vessels and planes during Fortitude.
Non-military camouflage experts, who would normally be working in theatres and film production, were relocated to Kent, where they built a dummy army.
Following deception strategies used in North Africa as part of Operation Bertram between 1941 and 1942, phantom Sherman Tanks were strategically placed on the coast around Dover in order to give German reconnaissance planes the impression of an imminent strike where they expected it: Calais.
Similarly, inflatable military trucks were placed around the coastal town of Hastings, supposedly as reinforcements for the phantom forces that were about to cross the Channel.
A mock fleet of aircraft carriers was also created by the camouflage and prop experts and later placed in rivers close to the English coast.
It is thought Operation Bodyguard was responsible for delaying Wehrmacht forces for seven weeks, making them believe that the attack most likely to happen was at Pas de Calais.
Meanwhile, the Allies had time and resources to focus on Operation Overlord, finalising the preparations for the Normandy landings and succeeding on D-Day, initiating the liberation of mainland Europe from Nazi control and victory in the Second World War.
Cover image: Inflatable Sherman tank (Picture: Imperial War Museum).