On D-Day, June 6, 1944 - 160,000 Allied troops stormed the coastline of Normandy France which began the liberation of Western Europe and brought years of careful and covert planning to an end. Preserving the element of surprise was crucial to D-Day’s success and there is one person whose singular contribution as a double agent played an instrumental role in the victory.

His name was Juan Pujol Garcia (codename: GARBO), a Spanish national hailed by MI5 as 'the greatest double agent of the second world war.'

Originally rejected by British intelligence services, Garcia would go on to infiltrate Nazi intelligence at the highest levels while working as an unauthorized, amateur spy. It is the incredible arc of his life story – a chicken farmer turned decorated double agent who faked his own death that is just as unlikely and fascinating as the web of lies he told the Nazis while operating as a rogue, one-man disinformation unit.

After being rejected on multiple occasions by MI5, the eccentric poultry-farmer decided to become a spy on his own, delivering fabricated intelligence to the Nazis in an effort to foil their strategies. The self-taught agent mastered the art of deception and disguise and was eventually recruited by MI5 to join their Double Cross System

Passports and exit visas were hard to come by during WWII but Juan Pujol Garcia traded six bottles of prohibited Scotch with a defunct Spanish Duke for a passport and convinced a print shop to forge him an exit visa

Prior to his successful career in espionage, Juan Pujol Garcia did not have much to show for himself. Born in 1912 to a wealthy family in Barcelona, he dropped out of boarding school and squandered away his privilege to attend an academy for poultry farmers. The hapless Spaniard was a chronic failure at almost everything in life. By the time he reached 30; Garcia had deserted the military, twice served time in prison, worked as a chicken farmer in France and completed two short lived stints as an owner/ operator of movie theaters.

'He had about as much chance of becoming a world-class intelligence operative as you or I have of winning the gold in the Olympic steeplechase,' said Stephan Talty, author of 'Agent Garbo' an interview with NPR.

Garcia was 24-years-old and unhappily engaged to a woman when Spain plunged into civil war. He was thrown into prison for failing to report to duty on the Republican side but escaped in the dead of night during a jailbreak led by a resistance group. Garcia then went into hiding and never saw his fiancee again. After spending a year in a Barcelona safe house, he emerged looking emaciated with forged identity documents that deemed him too old for the military he inexplicably joined the fight again, switching sides twice before he ended up back in prison for expressing sympathy toward the monarchy.

'Pujol was the Walter Mitty of the war,' Talty explained to NPR. The inveterate daydreamer with grandiose, (and often misguided) ambitions became disillusioned by the Spanish Civil War. Once Hitler began to wage his reign of terror across Europe in 1939, Garcia was determined to act on what he called a 'contribution toward the good of humanity.'

In an autobiography co-written by espionage expert, Nigel West, Garcia said: 'My humanist convictions would not allow me to turn a blind eye to the enormous suffering that was being unleashed by this psychopath.'

Juan Pujol Garcia poses with his wife, Aracelli who was very helpful in the beginning of Garcia's self-made spy career, acting as his emissary on the many overtures he made toward British intelligence services but eventually she tired of his lifestyle

Araceli instantly hated her new life in life in war-torn London; and MI5 was worried that she might turn on her husband and divulge top secrets to the enemy. Declassified MI5 documents reveal their effort to appease her; famously sending an MI5 agent to Lisbon to purchase 12 pairs of silk stockings as a bribe. Documents in the National Archive show that on March 4, 1943, CP Harvey, the agent sent to retrieve the stockings wrote: 'Herewith 12 pairs of stockings for Mrs Garbo for which I expect to be repaid 10 Shillings customs duty'

Garbo invented a fake network of 27 made-up operatives with very imaginative personas from a cave-dwelling waiter from Gibraltar to a retired Welsh sailor cum-Fascist-mercenary and an obsessive-compulsive Venezuelan codenamed MOONBEAM that lived in Canada. Germans were so grateful that they code named Garbo's network ‘Arabel,’ which means ‘answered prayers’ in Latin

It was around this time that Garcia was working as manager at a shoddy hotel in Madrid when he decided to pursue work as an Allied spy. Blinded by self-confidence and undeterred by his own tragic record of flops, he approached British intelligence officials at the embassy for an espionage job no less than four times, to which they politely declined, citing his obvious inexperience. Though he remained undaunted by rejection and resolved to become a spy on his own initiative.

He then offered his espionage services to the Germans knowing that if he could establish trust with the Nazis, he could eventually turn into a double agent for the Allies. This plan worked out better than he could have ever imagined.

In order to become a spy, Garcia first needed to procure a passport and exit visa; two precious items that were impossible to come by in the war torn country. Though he was nothing, if not resourceful and Garcia saw his opportunity when the Spanish Duke of Torre walked into the hotel one day lamenting his two aunts, pro-Franco princesses that were unable to find scotch during the war. Knowing he could obtain the liquor in Portugal, Garcia struck a deal with the Duke: a Spanish passport in exchange for six bottles of the illegal booze.

With a passport, Garcia arranged to meet with Gustav Leisner, head of the German military intelligence organization known as the Abwehr. Born with the gift of gab, Garcia professed his devout (albeit bogus) love for Hitler's Third Reich and spun circles around Leisner with his web of lies in which he listed names of non-existent diplomats that he was affiliated with. He was hired on the spot, given a crash course in spying and cryptology and sent on his way with a bottle of invisible ink, a codebook and £600 (roughly $40,000 in today's money) for expenses.

His marching orders were to go to London and establish a network of operatives, but Garcia did the exact opposite. Instead he moved to Lisbon to begin his self-made, imaginary spy career by delivering mocked-up reports to his Abwehr case officer in Madrid. He used maps, guidebooks and railroad timetables borrowed from the local library to make his reports seem more realistic. With information his wife, Araceli gleaned from newsreels and headlines, Garcia wrote lengthy, fictitious missives in his characteristically florid writing style about Allied airfields, British artilleries, and an entire Allied armada in Malta that Axis forces mistakenly responded to on the basis of Garcia's bogus intelligence, wasting precious time, resources and fuel.

Garcia was always ready with an excuse and despite the mishap, the Germans continued to trust him. In 1942 Karl-Erich Kühlenthal, a major in the Abwehr wrote to Garcia: 'Your activity and that of your information gave us a perfect idea of what is taking place over there; these reports, as you can imagine, have an incalculable value, and for that reason I beg of you to proceed with the greatest care so as not to endanger in these momentous times, either yourself or your organization.'

Soldiers carry a decoy rubber tank that was part of the large scale deception campaign known as 'Operation Fortitude.' From German spy planes flying overhead at high altitude, the phony munitions and fake military bases looked very real

Garbo went back to Normandy on the 40th anniversary of D-Day, the same year Ronald Reagan, Francois Mitterrand and Margaret Thatcher walked beaches attended the commemoration. One soldier present that day took Garbo by the hand and brought him to a group of veterans and said: 'I have the pleasure of introducing Garbo, the man who saved our lives'

As Hitler considered moving his fleet of deadly Panzer tanks to Normandy, Garbo wrote: 'I am of the opinion.. that these operations are a diversionary maneuver designed to draw off enemy reserves in order then to make a decisive attack in another place ... it may very probably take place in the Pas-de-Calais area.' One of Hitler's intelligence officers (assumed by historians to be, Friedrich Krummacher) underlined 'diversionary' in red pen

So beloved and valuable was Juan Garcia to the Nazis that he was given the codename 'Alaric,' which means 'everyone's ruler' in German and his phantom network of 27 operatives, was dubbed 'Arabel' meaning 'answered prayers' in Latin. Garcia's inveterate imagination proved handy when it came to inventing personas for Arabel, which included: a travelling salesman, a KLM pilot, an Indian poet named RAGS, a cave-dwelling waiter from Gibraltar, an employee of England's Ministry of War, a retired Welsh sailor cum-Fascist-mercenary and an obsessive-compulsive Venezuelan codenamed MOONBEAM that lived in Canada. These fictions spies filed expense reports and earned salaries, which amounted to a total of £17,554 (roughly $1million today) over the course of the war.

It wasn't until 1942 when Garcia finally (and accidentally) grabbed MI5's attention after one of his concocted reports regarding an Allied convoy of ships headed to Malta came dangerously close to the truth. They launched a massive manhunt for the suspected mole that they feared was trading their secrets only to discover the diminutive man living in Portugal that was single-handedly responsible for propagating a massive misinformation campaign to Nazis. Juan Pujol Garcia suddenly became MI5's most valuable asset.

Smuggled through Gibraltar, he was brought to the UK and worked as a double agent in the 'Double Cross System'- a top secret, counterespionage operation during WWII. His mastery in deception and disguise won him the codename 'GARBO' after Greta Garbo, the legendary Hollywood actress. Together with his MI5 field officer Tomas Harris, Garbo wrote 315 letters that averaged 2,000 words each, so satisfied were the Germans that they stopped recruiting spies all together.

More importantly, Garbo's letters were crucially used in breaking the enigma cipher. Nigel West, espionage expert and co-author of Garbo's biography told DailyMail.com: 'Garbo played a very significant role in that because if you have a cipher machine and you don't know the un-encrypted message at one end, then the encrypted message at the other end will be gobbledy goop. But if on the other hand, you already know the content of the original message, you can reverse engineer the cipher machine in order to get the key and read the traffic.'

Allied soldiers arrive in Normandy on D-Day which has been registered as the greatest-ever amphibious military offensive - a triumph of soldiering and seafaring, of industry, ingenuity and logistics

D-Day (also known as Operation Overlord) was not a guaranteed success. On June 5 1944, the night before the landing, Winston Churchill told his wife Clementine: 'By the time you wake up in the morning, 20,000 young men may have been killed.' Likewise, General Eisenhower was reduced to tears when a paratrooper in the 101st Airborne Division paused while boarding his plane to salute the Supreme Allied Commander who flashed a smile and responded in kind with the military gesture before he turned away and wept

In the beginning, Garbo gave Germans little bits of nonessential factual information to re-establish trust, overtime he would mix in falsehoods to throw them off and by the end he was passing on entirely invented information. In one instance, he sent a letter to the Abwehr that explicitly outlined details of the Allied attack on North Africa but intentionally delayed sending it by one day so it looked like a mere timing accident with the post. When it became clear that the Nazis intended to bomb civilian commuter trains, he sent them an outdated timetable. In 1943, Germans shot down a civilian plane carrying the Hollywood actor, Leslie Howard while travelling between Bristol and Lisbon and Garbo scolded them for doing it, mentioning that his imaginary agent working on their behalf could have been on board.

By 1944, the Allies devoted all their attention to planning the D-Day invasion of France and keeping its details secret was of the utmost importance. In an effort to do this, they launched a massive disinformation campaign that became known as Operation Fortitude. In unison with Double Cross spies that disseminated false intelligence, the plot also used false headlines, spoof radio broadcasts and even fake inflatable munitions to deceive the enemy. Meanwhile, Hitler knew that an attack was imminent and had prepared his defensive response for months but one crucial detail eluded him: the exact timing and location of the Allied landing.

Keeping the planned attack a surprise was key to the success of D-Day. Had the Germans been given any time to prepare, the outcome out have been very different. When Hitler finally realized that the Normandy invasion was no feint, General Eisenhower said, it was 'too late to have any effect upon the course of victory'

This is when Garcia's mastery in the art of espionage came into play. He was tasked with convincing Hitler that the attack would happen 200 miles away from Normandy in the more obvious location of Pas-de-Calais – the French region in closest proximity to Great Britain. He convinced Nazis that General Patton was forming an illusory million man army that was given a realistic name: the First United States Army Group (FUSAG). To corroborate this lie, newspapers published forged letters from local residents that complained about the noise and disorder from the amassing soldiers and printed images of King George VI visiting the pretend military base that was created with inflatable tanks, plywood planes, faux airstrips and empty buildings. Messenger pigeons tagged with FSUAG IDs around their legs were purposely released inside enemy lines.

On June 5, Garbo gave the Nazis instruction to standby for a very important message at 3am. In order to preserve his reliability with the enemy, he was going to reveal the actual targeted location (Normandy) but purposely too late for them to prevent the invasion that was already well on its way. But by luck, the Nazis missed the call as Madrid's radio operators were off air from 11:30pm until 7am. Garbo reprimanded his German case officer for missing the crucial dispatch, saying: 'I cannot accept excuses or negligence. Were it not for my ideals, I would abandon the work.'

One of the many lies leading up to D-Day that Garbo told was of the illusory 'million man' army that was commanded by General Patton. He called this fake division the 'First United States Army Group' (FUSAG) he led Germans to believe that FUSAG was gearing up for an attack 200 miles north of Normandy in Calais to which Hitler responded by reserving the majority of his military might for the supposed 'imminent' offense

Nigel West, the journalist who spent 12 years looking for Garbo eventually found him living with a new wife and children in Venezuela. He took flew with him back to France for the 40th Anniversary and recalls how Garbo returned from visiting one of the American cemeteries in tears. Confused, West reminded him that he was a beloved hero, to which Garbo replied, 'No. I was told that I saved many thousands of American lives, but looking at all these gravestones, I didn't do enough'

Juan Pujol Garcia reunited with his children in 1984 after Nigel West discovered Garbo living in Venezuela with a new family, 40 years after he faked his own death- neither his first or second families knew of each other's existence until he became headline news

Hitler was thoroughly confused. Thanks to Garbo he also believed that an impending attack in Norway was also in the cards and therefore reserved 250,000 troops in Scandinavia that were not present on June 6, 1944 – D-Day. His fleet of deadly Panzer tanks were standing-by in Calais for what they believed would be the real attack. Operation Fortitude worked so well that two days later, the Nazis still failed to throw the full weight of their military might on the beaches of Normandy.

On June 9, Garbo send a follow-up dispatch to the Germans: 'I am of the opinion, in view of the strong troop concentrations in southeastern and eastern England, which are not taking part in the present operations, that these operations are a diversionary maneuver designed to draw off enemy reserves in order then to make a decisive attack in another place ... it may very probably take place in the Pas-de-Calais area.'

This allowed the Allies to secure a strong foothold in France, even an entire month later, German troops were still waiting in the Pas-de-Calais. General Eisenhower said, 'The German 15th Army, which, if committed to battle in June or July, might possibly have defeated us by sheer weight of numbers, remained inoperative throughout the critical period of the campaign…' When Hitler finally realized that the Normandy invasion was no feint, Eisenhower said, it was 'too late to have any effect upon the course of victory.'

Berlin awarded Garcia an Iron Cross after the War, an accolade reserved for soldiers on the front line. In 1944, the King of England made Garcia a member of the Most Excellent Order of the British Empire but there was never an official ceremony since it had to be done in conditions of secrecy, Garbo was still an active agent. In 1984, the Duke of Edinburgh, a 'huge spy fan' according to West held a formal; investiture for Garcia

For his work, Garbo became the only person to have ever been awarded the Iron Cross from Germany and be made a member of the Most Excellent Order of the British Empire which is the country's greatest honor.

After the war Garbo moved with his wife, Araceli and three children to Venezuela where he eventually faked his own death with the help of Tomas Harris, his MI5 case officer and started a new family. It wasn't until 1984 when journalist, Nigel West discovered him living in Caracas after spending 12 years searching for him around the globe, convinced that his death was a mere 'cover-up.' West told DailyMail.com: 'Araceli was a very difficult woman and was very homesick and didn't like living in either London or Venezuela, she really wanted to go back to Spain. And Juan agreed that they would sell up and go back to Spain.' It was agreed that Araceli would take their three children to Madrid first and Garcia would follow a few weeks later after he finished tying up loose ends in Venezuela. 'But what actually happened was that quite soon after she arrived in Madrid, while waiting for her husband, a guy showed up from the British embassy and said, 'I'm very sorry, your husband has died,' which was not true.'

Nigel West escorted Garbo to Normandy for the 40th anniversary of D-Day when Reagan, Mitterrand and Margaret Thatcher walked the beaches. 'We left him alone in one of the American cemeteries and he came back after 20 minutes with tears rolling down his cheeks,' recalled West to DailyMail.com. Confused, West reminded him that he was a beloved hero to many to which Garbo replied, 'No. I was told that I saved many thousands of American lives, but looking at all these gravestones, I didn't do enough.'