Spies, espionage, resistance, and double-crossing were standard practices during the days of WWII. The Allied and Axis powers went to great lengths to spy on the opposing force. So in 1941, when a young ambitious Spaniard, Juan Pujol Garcia, approached the British’s Intelligent Service, MI6, offering to spy on the Germans, you would think they would’ve been only too happy to accept his offer. Surprisingly enough, he was denied three times by MI6.

This denial didn’t phase Juan. Instead he approached the Nazis, offering his services to them, with the full intent to be a double-agent and spy for the Brits. He told the Germans he was a Spanish government official with Nazi allegiance. Juan explained that the nature of his work involved his travelling to London. The Nazis were also hesitant at first but decided to bring him on board. They gave him a quick rundown on the basics of espionage and sent him on his way to England — or so they thought.

Instead, Juan Pujol moved to Lisbon, Portugal, and continued making efforts to work for MI6. In the meantime, he began to fabricate fictitious agents, making the Germans believe that he was indeed in England and that he had recruited new spies that were loyal to Nazi Germany. These “agents” would be pivotal in the years to come.

Finally, in 1942, Juan was able to connect with MI6 and was brought to London. Once in England, he was transferred from MI6 to MI5, the Security Service. This is where he was given the codename “Garbo.” He was assigned a handler, Tomas Harris. The Official History of British Intelligence described their relationship as “one of those rare partnerships between two exceptionally gifted men whose inventive genius inspired and complemented each other.”

Throughout the next two years, Garbo and Harris would create 27 fake agents, with full life stories, occupations, and roles. Harris and Garbo were constantly submitting false intelligence to Berlin, under the guise of these “agents.” The amount of work to accomplish this feat was staggering.

By the time 1944 came around, the Germans had full faith in Garbo and his army of “spies.” This proved priceless for the Allied build-up and invasion on D-Day.

The Nazis weren’t ignorant; they knew that a mass-scale invasion was inevitable. So, in January 1944, the Nazis tasked Garbo and his “team” to begin collecting any information pertaining to an Allied invasion of France. This request opened the doors for Garbo and the Allies to implement the biggest ruse and fake-out the war had ever seen. This would be Garbo’s greatest piece of work yet.

The Germans’ desperation for gathering intelligence, played right into the hands of the Allies. Operation Fortitude, the deception operation to mask the Normandy landings, was born and Garbo would play a key role in its success.

The Germans were correct that the Allies had began planning for an invasion of France. This plan was Operation Overlord, the famous invasion on D-Day.

Allied leaders knew that it was critical to convince the Germans that they would be invading France at Pas De Calais. Conveniently, that is where Hitler and others expected the invasion would happen.

Garbo’s mission was not to only trick the Nazis about the location of the invasion. After D-Day he had to continually convince the Germans that the main invasion had not landed and that the Normandy landings were a mere distraction from the main attack force that would be coming to Calais.

To accomplish this epic feat, an entire First U.S. Army Group, composed of 150,000 men, was staged in Kent and Essex under the command of General George S. Patton. The only catch: there was no real First U.S. Army Group. The Allies filled the area with blow-up tanks, fake trucks, empty barracks, and a mock oil depot. Meanwhile, Garbo and his agents continued sending messages to Berlin, telling them the invasion was coming from the Calais area. The Germans completely fell for it. He sold this so well, that until August the Germans still believed that another invasion was imminent.

Yet, not all high ranking German officers were convinced. Famously, Rommel had requested to move his forces to Normandy, but was denied. Speaking to Garbo’s contribution, the Official History of British Intelligence claimed that “intervention in the Normandy battle really might have tipped the balance.”

Hitler was so happy with Garbo’s work that he personally awarded him the Iron Cross for “extraordinary services.” Garbo’s response was his “humble thanks” and that he was truly “unworthy.”

Garbo would also receive an MBE from the British, presented by Sir David Petrie, the Director-General of the Security Services.

Thanks to Garbo, all German spies operating in England were caught during the war; many were turned into double agents.

Garbo eventually moved to Venezuela. MI5 did not release Garbo’s true identity until 1985, when Juan Pujol Garcia admitted his connection to the Security Service, in a book he wrote called “Operation Garbo.”