Seventy five years ago, on June 6, 1944 the largest amphibious invasion in military history occurred – it was D-Day and some 156,000 Allied soldiers landed in Normandy, France, beginning the liberation of Western Europe. The Germans – including Nazi dictator Adolf Hitler – believed this was a feint, a deception, with the real invasion still to come at Pas de Calais.
All the signs pointed in that direction. The First United States Army Group (FUSAG), was based around Dover just across the English Channel from Calais, and it was led by the very prominent U.S. General George S. Patton, considered by the Germans to be the best of the Allied military leaders.
Fake radio communication was sent out, inflatable tanks and faux landing craft were positioned around Southeastern England and soldiers were even sent out wearing shoulder patches on their uniforms for non-existent units. It was all part of Fortitude South, one part of the larger Operation Bodyguard, the codename for the WWII deception plan that was to fool the Germans into thinking that the invasion would be coming someplace other than Normandy.
One of the reasons it worked so well was that the Allies relied on a network of turned German spies. That was critical, because the Germans believed virtually everything these spies had been sending.
By the spring of 1944 the Allies had pretty much arrested or turned all the spies operating in the U.K., and thus began the largest misdirection effort in world history.
“Some of the information was passed on when it was too late for the Germans to do anything about it,” explained Dr. Vince Houghton, historian and curator at the International Spy Museum in Washington, D.C. “This was very coordinated with the British and because the information was true, even if useless by the time it was received, it helped convince the Germans that the agents could be trusted.”
Double Agents and the Double Cross System
Under an operation known as the “Double Cross System” the British turned agents. Among the most notable was Juan Pujol Garcia, a Spanish citizen who was first recruited by German intelligence. He successfully created an identity that he was a Franco-supporter, but in fact he wanted to make a contribution that he said was “for the good of humanity” and he offered his services to the British.
He became known as “Garbo” and misled the Germans, in part by creating a network of imaginary agents. His efforts were so successful that the Germans kept two armored divisions and 19 infantry divisions in Pas de Calais well after the Allies had secured a beachhead in Normandy.
“The combined deception around D-Day was so successful that it continued to work after the attack,” Houghton told ClearanceJobs. “It tricked the Germans so deeply that even as the Allies were breaking out from Normandy, Hitler didn’t want to release the troops from Calais because it was assumed Normandy was still just a diversion.”
Traffic analysis and unit patches: Layers of Deception
It wasn’t just the double agents that were crucial to misleading the Germans in advance of D-Day. Fortitude North, which was directed at convincing the Germans of an impending invasion of Norway, along with Fortitude South, sent out massive amounts of radio communication.
Much of it was in code. There was so much that the Germans simply couldn’t go through all of the intercepted communication. The volume of messages was just as important as what the Germans may have heard.
“This falls into the category of traffic analysis,” said Houghton. “The fact that there was so much radio communication helped make the Germans believe that it was about something important. That is traffic analysis, and even today the NSA sends out massive amounts to confuse those listening.”
Given the efforts with radio communication, inflatable tanks and other tactics – such as the fake shoulder patches –it could be argued it was overkill, given that virtually all the Germans agents were turned. But at the time, it was insurance.
“Hindsight is 20/20 and we know now that there was no German intelligence collection,” said Houghton. “But we didn’t know for sure that the all the German agents were ‘doubled.’ It wasn’t worth leaving anything to chance.”
Another part of it was that something as simple as having a few soldiers in town in different units would get noticed.
“In a way you’re counting on people talking, and understanding that this is the case,” added Houghton. “This was a force multiplier. You get a few dozen soldiers wearing patches with one unit, but the next day those same soldiers change clothes and suddenly it looks like thousands of soldiers. The same holds true for the reasons to put Patton in charge of the First United States Army Group.”
Beyond D-Day
While Operation Overlord, the codename for the overall invasion of Normandy, was a success in no small part thanks to deception, it should be remembered that similar tactics were used throughout the war.
One of the most notable examples of a successful deception effort was Operation Mincemeat, which was used to fool the Germans into thinking that the Allies were going to invade Greece and Sardinia rather than Sicily. This was accomplished by using the body of Glyndwr Michael, a British homeless man who died by ingesting rat poison, and having him dressed an officer of the Royal Marines. He was placed with personal items that identified him as Captain William Martin and his body was dropped in the sea so that he would wash up on the Spanish shore.
Attached to Michael’s body was a briefcase that contained seeming “secret documents” and the hope was that the Spanish might pass on the misinformation to the Germans.
“That effort did trick the Germans into thinking that the invasion was happening elsewhere,” Houghton told ClearanceJobs. “This is an example of how deception worked before D-Day, and continued to work afterward. But we should remember none of this was new just to World War II. Deception goes back thousands of years to Tsu Tzu and even the Greeks with the Trojan horse. It wasn’t something we made up just for June 6, 1944.”
