In the final years of World War II, both the Allied and Axis Powers knew that there was no chance of defeating Hitler without cracking his grasp on Western Europe, and both sides knew that Northern France was the obvious target for an amphibious assault. The German high command assumed the Allies would cross from England to France at the narrowest part of the channel and land at Pas-de-Calais. The Allies instead set their sights some 200 miles to the west. The beaches of Normandy could be taken as they were, but if the Germans added to their defense by moving their reserve infantry and panzers to Normandy from their garrison in the Pas-de-Calais region, the invasion would be a disaster. (Edit 4/16: A reader pointed out that the original post was incorrect about the Germans' assumptions about the invasion site. This paragraph has been changed to correct that information. -Matt)

Success, the Allies decided, would rest on distracting German forces and spreading them too thin across multiple invasion sites. They needed a way to credibly threaten Pas-de-Calais, scaring the Germans into keeping the reserves there and away from the actual battle. The resulting plan, Operation Fortitude, is one of the greatest lies ever told.

George and His Imaginary Friends

The Allied intelligence services created two fake armies to keep the Germans on their toes. One would be based in Scotland for a supposed invasion of Norway and the other headquartered in southeast England to threaten the Pas-de-Calais. The northern operation relied mainly on fake radio traffic and the feeding of false information to double agents to create the impression of a substantial army. Fortitude South, though, was well within the range of prying German ears and eyes, so fake chatter alone would be uncovered too quickly. The Allies would have to make it look and sound like a substantial army was building up in southeast England. They needed boots on the ground there, without actually using too much of their precious manpower.

When intelligence officers learned that the First U.S. Army Group (FUSAG) was to be redesignated the 12th Army Group, they knew they had their Pas-de-Calais invaders. The FUSAG was kept alive on paper, and the phantom army was given a few real soldiers and placed under the command of one of the era’s great military leaders.

General George S. Patton, nicknamed Old Blood and Guts, was feared and respected by Germans, more so than any other Allied commander. Today, he’s an American legend and a military icon, but in early 1944 he was almost out of a job. During the invasion of Sicily the previous summer, Patton had been visiting wounded troops at a field hospital when he came across Private Charles H. Kuhl slouched on a stool and suffering from battle fatigue. When Patton asked him where he was injured, Kuhl explained that he wasn’t wounded, but just couldn’t take it.

Patton didn’t like the answer, so he pulled out his gloves, slapped Kuhl across the face with them, and literally kicked him out of the hospital tent with an order to return to the front line. A media firestorm followed, and Patton was deemed a public relations liability and relieved of his command. He spent the rest of the year hopping around the Mediterranean making speeches, inspecting facilities and having his picture taken with troops.

When the phantom FUSAG got its marching orders, General Dwight Eisenhower, Supreme Commander of the Allied forces, struck a deal with Patton. The general would take command of the fictional army and stay out of trouble, and when the U.S. Third Army actually invaded France, he’d be given the reins.

Tricks of the Trade

Patton’s ghost army was based out of Dover, East Anglia and other areas of southeast England. The choice of location made it look like the Allies were going to push across the English Channel straight into the port of Calais, but also left the operation vulnerable to German snooping. To leave no doubt in Hitler’s mind that FUSAG was a formidable threat and that an attack on Calais was imminent, Allied intelligence launched a multi-pronged campaign of deception against the Germans.

Throughout most of the war, the German intelligence service and military brass believed that the Allied command in Europe was crawling with German spies. In reality, the British had quickly rounded up most of the Nazi agents as they arrived in the UK and turned them into double agents. Two of these spies were instrumental during Fortitude. Roman Garby-Czerniawski (codename Brutus) was a former Polish military officer who pretended to spy for the Germans and convinced his Nazi handlers that he was a liaison between Free Polish forces and Patton’s FUSAG headquarters. Juan Pujol (codename Garbo) was a Spaniard who’d previously trolled the Germans on his own before being recruited by the Allies and put to work feeding fake info to the Nazis on FUSAG’s manpower, maneuvers and battle readiness. British intelligence also passed fake info off to Germany through civilian channels. For example, letters were printed in the local newspapers near FUSAG’s supposed base voicing complaints from citizens about noise and the behavior of the troops.

On the ground in southeast England, something also had to be done about the Germans’ reconnaissance planes. There were a few real American and British units in the area, temporarily assigned to FUSAG before actually heading to Normandy, but the view from above was not impressive. The fake intelligence and chatter was creating the impression that FUSAG was larger than any other Allied army operating in Europe, so now it had to look real and like it meant business.

To bring FUSAG off of paper and into the real world, the Allies built a cleverly conceived, sort-of-real-but-mostly-fake base for the army. Mess tents, hospital tents, ammo caches, toilets, fuel depots and parking areas were built all over the southeast. The parking lots were filled with fake jeeps, trucks and tanks built from cloth and plywood. Inflatable rubber vehicles were also deployed (but frequently fell victim to curious cows from the local farms). Every night a group of soldiers was responsible for picking up and moving the fake vehicles around the bases for the sake of realism, one of them using a custom-made rolling tool to make “tire tracks” in the dirt.

The harbors of the area likewise had to be populated by a false Navy, and British movie industry pros were brought in to “dress the set.” They constructed landing craft, support boats and even an oil dock from wood and fabric and floated them on oil drums.

Waiting for the End of the World

As D-Day loomed, the Allies wondered if their ruse was working. The interception and decryption of German radio traffic (aided by the well-timed arrival of a captured German code machine) gave them a resounding “yes.” The Germans were buying FUSAG and the Pas-de-Calais invasion hook, line and sinker, but the lie could not unravel just yet.

On June 6, the Allies landed at Normandy. As the battle raged there and the Germans considered sending reinforcements, the Allies kept spinning the story, lest the panzers in Calais roll up behind the real Allied armies as they moved up and off the beaches. The waters around southern England were jammed with fake boats and even a few real battleships, the scripted radio traffic went silent, smokescreens were laid, and boats swept the Channel for mines, all to give the impression that another attack was imminent. Brutus and Garbo continued to mislead their German superiors, telling them that Normandy was just a distraction and Patton’s army was going to embark in just a few days for the real invasion.

On June 9, Garbo radioed in to his German contacts and transmitted for a full two hours with false troop movement reports, descriptions of the landing forces, and a reassurance that FUSAG’s true target was the Pas-de-Calais.

The message went all the way up the chain to Hitler, who not only cancelled an order to send the Calais forces to Normandy, but actually rerouted reinforcements coming from other areas away from Normandy and to Calais. During the D-Day landings and for weeks after, as the Allies - including Patton and the US Third Army - moved deeper and deeper into France, the Germans continued to hold onto Calais for dear life. It wasn’t until Patton’s real army began to prod them from the south that the panzers and infantry moved out, after they’d spent almost the whole the summer waiting for an assault that never came from an army that didn’t exist.