General Hans Cramer was a German officer of the formal, Prussian school. Strict, proud and rigid, he did not take kindly to surrendering. Forced to admit defeat in Tunisia in May 1943, his army disintegrating around him, he insisted on wearing his finest dress uniform to the last. He and the general accompanying him when they surrendered to a British officer were dressed immaculately in long-waisted tunics, green breeches and highly polished boots. When asked to hand over their pistols they contemptuously threw them down at the officer’s feet.

However, on arrival in Britain some weeks later Cramer was in a rather better mood. Senior Wehrmacht commanders were sent to Trent Park, a magnificent Georgian mansion to the north of London, and lived in some luxury while incarcerated there. They were served good food, were permitted to take walks in the spacious grounds and allowed a ration of whisky every evening. Cramer had his own bedroom, sitting room and a batman to attend to him. The grandeur of the surroundings played on the general’s sense of self-importance. No wooden huts and barbed wire for him.

Hans Cramer, the last commanding general of the German Afrika Korps before its surrender, in May 1943.

Moreover, Cramer was encouraged to listen to BBC radio and to talk freely with the other senior generals. But there was method in the madness. The house was like a large studio set with hidden microphones behind every painting, inside every plant pot and even under the floorboards. British intelligence officers listened in as the German officers discussed many aspects of the war. Their postprandial conversations yielded many fascinating gems of intelligence about future military plans and scientific projects that some of them thought would help rescue the Third Reich.

In the spring of 1944 Cramer was mysteriously transferred from Trent Park to a camp in Wales. In May, as he was in failing health, it was decided to release him as part of a prisoner exchange. He would be repatriated to the Third Reich via the Swedish Red Cross. On the day of his release a car came for him with a driver, a guard and two British officers as an escort. The journey from Wales to a port on the south coast from where he would sail to Sweden was long. The two escort officers were extremely friendly and chatted in German with him. Soon they found themselves surrounded by large numbers of Allied troops, American and British, all clearly preparing for a big event — the invasion of occupied Europe.

Cramer grew wide-eyed at the scale of activity he saw out of the car window. He was also amazed at how indiscreet the chatty officers were. Another sign of the lack of soldierliness of the British, he thought. The two officers let it be known that they were driving through Kent. As all road signs had been removed years before to confuse the Germans in the event of an invasion, Cramer had no reason to doubt what he heard.

In fact the pair were not army officers at all. They were from MI5 — part of what was known as the Double Cross team. The whole charade was just one element in the deception leading up to D-day — a grand plan to convince Hitler that any Allied invasion of mainland Europe would come not on the beaches of Normandy but 200 miles away to the north, around Calais.

The house was like a large studio set with hidden microphones behind every painting.

In 1944 the Germans had a large force, the 15th Army, consisting of two panzer divisions and several infantry divisions, protecting the well-fortified Calais coast. The objective of the ambitious British deception plan was to keep that army there, well away from the Normandy landings.

On returning to Germany, Cramer was soon telling his old boss, Rommel, that he had seen evidence of a large army in Kent preparing for an invasion just across the Channel to the Pas-de-Calais. Cramer had seen genuine troops preparing for a real invasion. But in reality he had not been in Kent. He had been driven near to the Dorset coast, where Allied troops were amassing before D-day.

Cramer was whisked away to Hitler’s mountain retreat in Berchtesgaden, where he repeated what he had seen and heard to the Führer. How could Hitler fail to be impressed by a report from one of his most-decorated generals of what he had seen with his own eyes? Misleading Cramer was an ingenious piece of playacting from inventive minds within British intelligence. But it was only one of many deceptions.

The Real Army—and a Pretend One

The planning for Operation Overlord, the Allied invasion of northern Europe, was on a colossal scale. A quarter of a million men assembled in a series of encampments across southwestern England with all their vehicles, weapons and armored support. Seven thousand vessels would carry them across the Channel to Normandy.

The invasion fleet of transports, landing craft and assault ships was supported by 7 battleships, 23 cruisers and 104 destroyers. Dozens of squadrons of Allied fighter aircraft would keep the skies clear of Luftwaffe counterattacks. The night before the invasion three divisions of Allied airborne troops would be dropped to secure key points on the flanks of the assault. By sea more than 132,000 men would land on five beaches on a 50-mile stretch of Normandy coast. Two gigantic floating harbors would be towed in separate pieces across the Channel from ports as far north as Scotland and assembled off the beaches. Overlord was probably the most daring and certainly the most complex operation of the war.

The American military leaders had wanted an invasion of northern Europe at least a year earlier. The British prime minister, Winston Churchill, and his military chiefs had argued for postponement. They had lived through the disaster of Dunkirk, the evacuation of more than 338,000 Allied troops in 1940, and knew that a failed landing before aerial and naval supremacy had been secured would spell disaster and set the war back by at least a year. Finally, under pressure from Stalin, who rightly felt the Soviets were bearing the brunt of the land war with Nazi Germany, it had been agreed to go ahead with the invasion in June 1944.

At the same time, as the Allies agreed to launch the invasion on what would be called D-day, they agreed to begin the deception that would fool the Germans as to when and where it would come. “In wartime, truth is so precious it should always be attended by a bodyguard of lies,” Churchill told Stalin.

General Montgomery’s chief deception organizer argued that it was not enough to make the Germans think an invasion was coming in the Pas-de-Calais; the Allies had to act as though this was the case. The deception planners came up with the idea of creating a hoax army in southeast England, in Kent, Essex and Suffolk, that looked as though it was training to invade across the shortest stretch of the Channel. At first such a vast deceit seemed impossible. How could they conjure an army of a quarter of a million men that didn’t exist? Quickly they realized that they had to find a way.

First they gave the force a name — the First US Army Group — better known by its acronym, Fusag. German signallers had picked up on the existence on paper of such a unit earlier in the year. Now the Allied deceivers pretended that this force was to spearhead the invasion. To make it realistic it had to include some real troops, so several US and Canadian divisions that were in reality training for the Normandy invasion were allocated to Fusag in the early months of 1944.

New fictitious divisions were also added and given names, insignia and located at training camps or barracks. Signals units were dispatched to start sending the sort of messages that such divisions would, in reality, create. A host of orders and instructions were sent down the command chain that would be picked up by German interceptors. They were sent in code, but some so simple that the Germans could easily make sense of them.

How could they conjure an army of a quarter of a million men that didn’t exist?

Along with formal military plans and outlines of training regimes, these signals included gossip about officer promotions and courts-martial, just as would have been the case had such units actually existed. Soon German military intelligence began to report on the assembly of a large army of troops in the southeast of England.

Rubber Tanks and Fake News

This imaginary army had to be equipped accordingly. Set designers and technicians from Shepperton film studios were asked to design dummy landing craft, tanks and aircraft that would look real if photographed by German reconnaissance aircraft. The landing craft were about 170ft long and 30ft wide, made out of heavy canvas stretched across a steel frame and floated on empty oil drums.

Two battalions of the Worcestershire Regiment were trained to assemble them and it took 30 men about seven hours to build a dummy landing craft under cover of darkness. Two hundred and fifty of these were built and “launched” at harbors in Dover and Folkestone. They were moored along the Essex coast, on the rivers Orwell and Deben in Suffolk, and as far north as Great Yarmouth in Norfolk.

Decoy landing craft, made by the “Ghost Army,” a special military unit comprising 1,100 artists, sound engineers, and set designers.

Large numbers of dummy tanks made of rubber and canvas on a metal frame were built and stored in long lines in assembly areas. Dummy aircraft were built and lined up on the tarmac on RAF airfields. And a large oil storage facility was built just outside Dover as a copy of the facilities being built in the southwest. But this one consisted of nothing more than canvas, wooden scaffolding, fiberboard and old sewer piping recycled from bombsites. From the ground it looked like a stage set. But it was only ever intended to be seen by the enemy from the air.

Allied reconnaissance aircraft were flown over the sites to photograph the dummy camps. RAF photo-interpreters were then asked to examine the aerial images. They announced they were not impressed. The machines looked convincing enough but the sites lacked a human presence. They said the formations would not convince an experienced photo-interpreter. So several battalions were ordered in and told to start brewing up in the early morning when the German reconnaissance aircraft were likely to pass overhead. The smoke from their fires would make it appear that large numbers of men were living alongside their equipment. They were also told to hang out towels and underclothes on washing lines.

When everything was ready, the Allied military authorities adopted a policy of what they called “discrete display” in the southeast of England, allowing occasional German reconnaissance planes to fly over the area to observe what was going on. This was in marked contrast to the southwest, where everything was hidden under camouflage and the assembled troops were allowed to use only smokeless fuel so as not to give away their position.

All the dummy sites were closed to the public but there were many challenges in keeping the plans secret. A sailing barge ran into one of the hoax landing craft one night on the River Orwell, near Felixstowe, and it promptly fell apart. No doubt the crew of the barge were astonished — but to prevent them from telling anyone what they had seen they were arrested and held in custody until after D-day. Churchill visited one of the dummy tank assembly areas and was much amused when he saw four men lift up and carry away a Sherman tank that if real would have weighed more than 30 tons.

The deceivers thought creatively about the impact that large numbers of American troops would have had on Kent or Essex villages. They got local newspapers to publish articles about villagers complaining of country lanes being blocked by American Jeeps and trucks. Letters were sent to newspapers about how American GIs were corrupting the local women. And someone wrote in complaining about the disgusting number of prophylactics he had discovered in a wood. These articles and letters were passed on to the various double agents operating under MI5’s control, who duly fed them into German intelligence.

So Fusag had the troops needed to make up a large invasion force, was transmitting the sort of signals such units would generate and had the equipment necessary to mount a mighty cross-Channel operation. But it needed one more element to make it credible. Fusag required a commander whom the Germans would believe could lead the invasion.

The Showman General

General George S Patton came from a long line of American generals; 16 members of his family had fought for the Confederacy in the Civil War. He liked to lead from the front, had an aggressive nature and was one of the greatest tacticians and tank commanders of the Second World War. But in 1944 Patton was playing no part in the planning of the real invasion as he had disgraced himself the previous year.

American general George S. Patton arrives in the U.K. to begin his command of the hoax army.

While commanding troops in Sicily, Patton had viciously slapped some hospitalized soldiers suffering from war trauma — what we now know as post-traumatic stress disorder. He had threatened to shoot them if they didn’t pull themselves together and get back into battle. There had been calls to send Patton home, but his commanding officer, General Eisenhower, decided to keep him on in the hope that he could find a role for him. Now his moment had come.

Set designers and technicians from Shepperton film studios were asked to design dummy landing craft, tanks and aircraft that would look real if photographed.

Patton was put in command of Fusag. Without doubt he would have preferred to be leading real troops, but as a natural showman he took to this new task with vigor. With a rodlike straight back, resplendent in a smartly tailored uniform, he looked the epitome of a great commander. Everywhere he went he was accompanied by photographers.

He made speeches to troops in divisions that didn’t exist, inspected tanks in pretend armored units and was even joined by King George VI once or twice as he travelled around the southeast of England. The Germans thought Patton was one of the best generals the Allies had and entirely believed he would be the man appointed to command the upcoming invasion.

Moment of Truth

Germany’s Field Marshal Gerd von Rundstedt, commander in chief of the armies in the west, had become convinced from intelligence reports that the real invasion would come from southeast England to the Pas-de-Calais. But in the early months of 1944 Hitler began arguing that Cherbourg in Normandy would be the Allied objective. At other times he said it might be launched against Norway or the Netherlands. Probably he wanted to record belief in all options so that whatever happened he could claim to have been right. But by late spring he seemed more certain.

On May 27, just ten days before D-day, Hitler had a meeting with the Japanese ambassador to Berlin, Hiroshi Oshima. Hitler spoke openly and honestly, telling Oshima that wherever the invasion came first, this would be a feint as the Allies would then “come forward with an all-out second front in the area of the Straits of Dover”. A transcript of their conversation was sent by Oshima to Tokyo. This was intercepted, deciphered and read with delight by Eisenhower and his team. They could barely believe how Hitler himself had taken the bait. It was as though they had written the Führer’s script for him.

The Germans also had a source in Britain whom they codenamed Josephine. There has been much debate over the years as to who Josephine was. Recent research has pointed the finger at Anthony Blunt, a senior figure within MI5 who was later outed as a Soviet double agent. In any case, in advance of D-day nothing they heard from Josephine contradicted the deception operations.

The D-day landing, at Normandy.

The invasion was finally launched on Tuesday, June 6, a day later than scheduled because of a storm in the Channel. News of the landings was to be withheld until 9.30 that morning, when all BBC radio stations would interrupt their broadcasts for the newsreader John Snagge to announce that “Allied naval forces, supported by strong air forces, began landing Allied armies this morning on the coast of northern France”, but omitting precisely where.

However, Berlin Radio had beaten the BBC to it. At 8am its newsreader had announced that Allied landings were taking place. The news was brief but the radio producers went on to report what they were sure was happening, that Allied troops were coming ashore in the Pas-de-Calais.

In reality from the early hours of June 6 Allied soldiers landed across five Normandy beaches — codenamed Sword, Juno, Gold, Omaha and Utah — eventually linking up to form a beachhead and push inland.

For six weeks after D-day the German high command refused requests to transfer troops from the Pas-de-Calais. Hitler and von Rundstedt continued to believe Normandy was a diversion and that a second more significant invasion was still coming from Patton’s forces into the Calais coast.

Adolf Hitler, Heinrich Himmler (at Hitler’s left), and military staff look across the English Channel from Calais, contemplating the possibility of an invasion.

By inventing an army that never was, the Allied deceivers had kept key German forces twiddling their thumbs around Calais while some of the decisive battles of the war were being fought hundreds of miles away. The invasion proved a great success but would be followed by nearly two months of intense fighting to break out from Normandy. In August the Allies liberated Paris; in September Brussels. But it was another six months before they crossed the Rhine. The final German surrender did not come until May 1945. Without any doubt it would have been much later had D-day — and its extraordinary deception force — failed.

Excerpted from The Army That Never Was: D-Day and the Great Deception, by Taylor Downing, out now in the U.K. and publishing in December in the U.S.

Taylor Downing is a U.K.-based historian and television producer