[Crowd cheers] -Firepower, fortifications, troops, and tanks often dominate stories of the Second World War.

What can sometimes go unnoticed is the role of deception in military strategy.

Camouflage, decoys, and disinformation all became tools for the Axis and Allies alike.

-Deception played a major role in the Second World War.

It was practiced on the largest scale it's ever been practiced in the history of warfare.

-Strategies ranged from a simple feint performed in the midst of battle to complex, long-planned campaigns designed to completely alter the enemy's perspective.

-The whole point in military deception and intelligence operations is to try and get the enemy to do what you want them to do, because that means you have a better chance of things going your way.

-There's no doubt that deception helped to save lives and bring a swifter end to World War II.

-The stories behind some of the most extraordinary feats of espionage and strategic subterfuge the world has ever seen.

-It changes the character of war, and it changes the way that war is waged.

And that's not gonna change back.

♪♪ [Gunfire] [Indistinct shouting] -On June 6, 1944, 156,000 British, American, and Canadian troops invaded Normandy in northern France as part of the largest amphibious military operation in history -- D-Day.

The liberation of Europe was about to begin.

-We believe that the Nazis and the fascists have asked for it, and they're going to get it.

-As the Second World War approached its climax, stolen secrets, decoy missions, and international espionage by both sides played a decisive role in the outcome of the war and changed the world forever.

♪♪ Weeks after the Western Allies invaded Normandy, Soviet Russia launched a vast offensive against Germany on the Eastern Front.

-German priorities had shifted.

No longer was the Eastern Front the dominant area for all priorities.

That's now shifted to the West, and the Eastern Front is just having to make do with what it has.

It makes intelligence more important than ever.

-Using secrecy and stealth, Soviet intelligence set out to deceive the Germans into making a fatal mistake.

♪♪ ♪♪ By June 1944, German forces had been in Soviet Russia for almost three years.

-After initial, rapid advances, albeit in the face of increasingly ferocious Soviet resistance and difficult environmental conditions and poor transport infrastructure, the Germans were rapidly worn down by the effort involved in trying to defeat the Soviet Union, and by the summer of 1944, the Red Army had advanced on the north of the front and particularly in the south, in the Ukraine, as it was called then.

And the result was that German Army Group Centre's position in Belorussia jutted out in the middle of the Eastern Front, and it was vulnerable to Red Army attack.

♪♪ -As dawn broke on June 22, the Red Army opened fire on the German-held salient surrounding Minsk, known as the Belorussian Balcony.

The German Army Group Centre was faced on three sides by 1.7 million Soviet troops.

They were taken by complete surprise.

Soviet maskirovka -- the Russian term for the art of deception -- had convinced German leader Adolf Hitler that any Soviet offensive would come hundreds of kilometers south.

Months earlier, Soviet intelligence reported that Hitler suspected a Red Army attack in Ukraine.

In response, Soviet leader Joseph Stalin ordered a deadly double bluff, codenamed Operation Bagration.

The Soviets began to simulate military preparations in Ukraine to distract the Germans from their real target, the Belorussian Balcony.

Only Stalin and his most trusted generals knew of the full extent of the deception.

-Operational security, which is another major tenet of maskirovka, is absolutely in evidence here.

They are being super secretive, not just for the Germans, but for their own forces.

And they are giving strict instructions that the normal intelligence operations that would precede a major offensive -- aerial overflights, seizing prisoners -- these are not to take place really in any part of the front that isn't absolutely a priority, again giving the Germans the impression "Nothing to see here."

-By day, the Soviets assembled huge phantom forces -- false concentrations of men and vehicles in Ukraine.

Dummy artillery and tanks were conspicuously moved into position along the Ukrainian front.

Meanwhile, by night, the Soviets moved 75,000 railway carriages of troops, vehicles, and weapons to the Belorussian Balcony.

-How are they doing that?

They are driving at night with no lights.

They can't be seen doing it.

So what the Soviets do is they put white posts all the way along these roads, and they paint white stripes on the back of all the vehicles so that they can have some idea of where they are having to move.

They are having to reach predesignated depots, where they can all be disguised, so that during the day there's no evidence of this movement.

And in fact, if they don't reach those predesignated employment areas, they are having to camouflage all their vehicles on the road.

At first light, Soviet planes go up, and they are looking for their own troops.

And if they can see them, they drop pennants down to tell them, "You're visible from the air.

Redouble your efforts at camouflage."

And this is very successful.

-Fake radio chatter around Ukraine was amplified to suggest to Germans listening in that Soviet battalions were poised to move forward there.

-The Germans really had no idea where the blow would fall, because they were almost entirely lacking in air reconnaissance by this stage.

And even then, they still had just about enough information from prisoners they were taking on the front line and various other nuggets, but they really had no idea about the numbers of troops massing in the rear along the various sections of the front.

-Soviet tank armies intended for Operation Bagration were held in Ukraine until they were moved north at the last moment.

Yet one highly skilled unit stood in the way of the Soviet plans -- the infamous German Army Group Centre.

Army Group Centre had almost captured Moscow in 1941.

It was made up of 38 battle-hardened German divisions that for three years had ruthlessly spearheaded the invasion of the Soviet Union.

-The Germans expected that the biggest blow the Soviets would inflict upon them at that particular point would not fall against Army Group Centre, but would fall to the south of it against Field Marshal Model's Army Group North Ukraine.

-The Soviet deception was working.

German high command believed it safe to move troops and tanks away from Army Group Centre to reinforce their armies in Ukraine.

-For 2 1/2 years, Army Group Centre had fought on the defensive and fought remarkably successfully.

Army Group Centre was the army group that typically held its line.

And this is the context that those same commanders take into the summer of 1944.

In the first instance, they're being told by their own intelligence services that the Soviets are concentrating on other areas of the front.

And in the second instance, they have confidence in their multiple lines that they have built at the front.

-Hitler's Chief of Staff, General Kurt Zeitzler, redirected 88% of Army Group Centre's tank strength and 100,000 of its men to Ukraine.

This would prove to be one of the most calamitous military decisions of the Second World War.

June 22, three years to the day after the Germans had invaded Russia, the Soviets unleashed their assault on Army Group Centre.

♪♪ ♪♪ Stalin's forces surrounding the Minsk salient struck simultaneously.

Within days, the undermanned and underprepared Army Group Centre was collapsing under the relentless Soviet pressure.

-There were some very sturdy, resilient German generals, but the commander of Army Group Centre, Field Marshal Ernst Busch, was not one of these commanders.

He reacted very much like a rabbit in the headlamps.

-Operation Bagration forced the Germans to fight on two fronts -- France in the west and Belorussia in the east -- draining Hitler of resources and men.

By mid-August, the Soviets had pushed the Germans back to Warsaw.

-It's not just that they've broken Army Group Centre.

It's not just that they've destroyed three German armies.

But from west of Orsha, where Operation Bagration begins, right through to Warsaw is 700 kilometers.

That's more than half of the distance from the starting Soviet positions to Berlin.

It's only another 500 kilometers from Warsaw to Berlin.

-A disastrous, indeed catastrophic blow for the Germans on the Eastern Front.

This is symbolized by the sight of 57,000 German prisoners being paraded through the streets of Moscow in the aftermath of the operation, like something from an ancient Roman triumph.

♪♪ -The Western Allies had delivered the first blow against the Germans when they invaded Normandy.

The Soviets dealt the second blow with Operation Bagration, signaling the beginning of the end for Hitler's Third Reich.

Whilst the German war machine was starting to fall apart in Western Europe, in the Far East, a decisive battle in the Pacific was about to begin.

October 1944.

As American troops fought for control of the Philippines, the Japanese lured Admiral William Halsey and his mighty 3rd Fleet away from the action, leaving the United States invasion force on the very brink of catastrophe.

♪♪ ♪♪ October 20.

American troops landed on the island of Leyte.

-By the fall of 1944, General Douglas MacArthur wanted to return to the Philippines.

He had evacuated in 1942, but he'd promised the Filipino people that he would return.

So in October 1944, it was decided that he would land 200,000 soldiers of the Sixth US Army on the island of Leyte.

-General MacArthur landed at Red Beach, followed by 130,000 troops who disembarked from Admiral Kinkaid's 7th Fleet amphibious landing vessels.

As the Americans stormed ashore, they were protected from a Japanese naval counterattack by the formidable U.S. 3rd Fleet, commanded by an admiral with a reputation for risky, aggressive tactics -- William "Bull" Halsey.

-You have this incredible armada.

However, there were some problems with this, because Kinkaid reported directly to Douglas MacArthur and Halsey was in another chain of command.

And so the communications among the three commanders were not very effective.

-The Japanese moved to defend the island, and the largest naval battle of the Second World War began -- the Battle of Leyte Gulf.

♪♪ ♪♪ Amid fierce fighting, Halsey met Vice Admiral Takeo Kurita's Center Force and sank the Musashi, pride of the Japanese Navy, pushing Kurita rapidly back westwards in retreat.

Halsey was buoyant.

♪♪ At 16:40 on October 24, a U.S. reconnaissance plane spotted a second Japanese fleet under the control of Vice Admiral Ozawa, 480 kilometers north of Leyte.

For hours, Ozawa had sailed back and forth across Cape Engaño, hoping to be spotted.

-The Japanese wanted to deceive the Americans by utilizing Sho-Go 1 battle plan.

This would be a plan in which Vice-Admiral Ozawa would basically lure or decoy Halsey away from the Americans at Leyte Gulf, away from MacArthur, away from Kinkaid, leaving them vulnerable to this battleship surface attack.

-The deception worked.

Halsey, aboard the New Jersey, set off after Ozawa, along with every available ship under his command.

Six battleships, 5 aircraft carriers carrying 600 aircraft, and 40 destroyers steamed northwards.

-That was a major error.

Admiral Halsey never admitted that he made any error.

The answer is simply this -- if you are doing something what your enemy wants you to do, you possibly cannot claim that the decision was sound.

-Kinkaid's 7th Fleet and MacArthur's invasion force were now left dangerously exposed.

That night, Admiral Kurita's Center Force, including the Yamato, the sister ship of Musashi and one of the biggest battleships ever built, doubled back.

Kurita passed through the San Bernardino Strait unchallenged, with the American amphibious forces in his sights.

As the sun began to rise, 7th Fleet lookouts saw pagoda masts on the horizon -- Kurita's advancing Center Force.

All that stood between Kurita and a massacre of the Americans at Leyte Gulf was a small 7th Fleet escort carrier group known as Taffy 3.

They were not at all prepared for the mighty Japanese fleet that confronted them.

In desperation, Kinkaid called for assistance.

But Halsey turned a deaf ear, ignoring pleas for help.

Informed of the impending disaster, Admiral Nimitz sent one of the most notorious messages in naval history to the New Jersey -- "Where -- Repeat, where is Task Force 34?

The world wonders."

The final three words had been intended as nonsensical padding to confuse enemy cryptanalysts, but Halsey interpreted the phrase as a sarcastic rebuke.

Incensed, Halsey waited another hour before responding.

Instead, Halsey continued his pursuit of Ozawa's decoy fleet.

In chasing the Japanese deception, Halsey lived up to his reputation as a risk-taker.

but his gamble did not pay off.

Although he destroyed four of Ozawa's carriers, he had left Taffy 3 and the American amphibious forces facing almost certain annihilation.

♪♪ In the early hours of 25 October 1944, Admiral Kurita's Center Force closed in on Rear Admiral Clifton Sprague's Taffy 3 near the island of Samar.

Watching their approach, Lieutenant Commander Robert Copeland addressed the crew of USS Samuel B. Roberts, one of Taffy 3's destroyer escorts.

He told them, "This will be a fight against overwhelming odds from which survival cannot be expected."

Taffy 3 had neither the firepower nor the armor to match the 23 ships of the approaching Japanese force.

-Admiral Kurita enjoyed every advantage over the Americans at this point.

He had four battleships.

He had several cruisers and destroyers.

The combined weight of the American forces did not equal the 70,000 tons of the super battleship Yamato.

In fact, one of the turrets with the 18.1" guns on the Yamato was equal in weight to an American destroyer.

-At 7:00 a.m., the Japanese opened fire.

♪♪ Rear Admiral Sprague knew that thousands of Americans landing at Leyte would die if the Japanese reached them.

In desperation, Sprague ordered his ships to billow dense smoke from their funnels.

Camouflaged, the American destroyers began what seemed a suicidal charge towards the Japanese armada.

The USS Johnston was among the first to engage the Japanese, zigzagging at maximum speed in and out of the smoke.

She fired 500 shells into Kumano, a ship five times her size.

As both sides exchanged torpedoes, Sprague ordered Taffy 3 to retreat east into a storm, intending to exploit the bad visibility and stall the Japanese advance.

The smoke-filled melee was confused further by Japanese shells, which each carried different-colored dye so that ships could see where their shots fell.

Blue, green, pink, and yellow fountains of water exploded with every Japanese shell.

As they did, American commanders ordered their ships to weave between the explosions and conceal their ships amid the puffs of color.

♪♪ The American ships were supported by Wildcat fighter planes... and Avenger torpedo bombers which took off from Taffy 3 escort carriers.

-Those airplanes on those light aircraft carriers were armed to bomb ground targets on Leyte to help MacArthur's forces.

They would fly just dry runs against the Japanese warships, even if they had no bombs or no ammunition, no bullets, just to try to disrupt the Japanese operations.

♪♪ -Amid the mayhem, Kurita mistook Taffy 3's ships for much bigger warships.

-They put up a heroic, courageous fight.

They basically deceive him.

Their bravery made Kurita begin to think to himself, "Well, if destroyers are attacking me like this, maybe there's a major fleet beyond the horizon or beyond that smokescreen."

-Unaware that Bull Halsey was still chasing Ozawa hundreds of kilometers away, Kurita became convinced that he was in fact facing Halsey's 3rd Fleet.

At 9:20, to Sprague's amazement, Kurita's ships turned away in retreat and withdrew from the San Bernardino Strait.

Admiral Halsey finally sent his fast battleships back, but they were too late to cut off Kurita's escape or help Taffy 3, which had lost 5 ships and over 1,000 men.

Days later, the battle for Leyte Gulf ended in an overwhelming American victory.

-This was the last major offensive that the Japanese would try during World War II.

They were reduced to leaving their warships in harbor and occasionally coming back to attack the Americans and suicide attacks.

♪♪ So this is the last great naval battle of World War II, and the Japanese never again pose a threat to the Americans.

♪♪ [Wind howling] -The winter of 1944 arrived.

Although the Allies were on top in the Far East, the Allied advance in Europe had lost momentum.

-By December 1944, the Red Army in the east and the British and American-led Allies in the west had forced the Germans back to their own frontiers.

But they weren't able to finish the job that year.

-The Normandy landings had given the Allies a foothold in northern France and Belgium, but the German Wehrmacht remained a force to be reckoned with.

-Even at this late stage in the war, there was a great deal of high-quality, resilient manpower in the German Army, very adept at defensive warfare.

♪♪ -Hitler decided to launch one last massive assault against the Allies.

December 1944.

Amid fierce fighting on the Western Front, a band of German commandos infiltrated the Allied camp, sowing chaos and confusion in one of the most audacious undercover missions of the Second World War.

♪♪ 16 December.

In the early hours, two German Panzer armies crashed through a lightly defended section of the American lines in the Ardennes Forest, marking the start of the Battle of the Bulge.

♪♪ -The Ardennes offensive was an offensive -- an armored offensive by German forces through the Ardennes sector on the German-Belgian border in December 1944, and it was Hitler's last throw of the dice.

It was Hitler's final attempt to change the strategic direction of the war.

-As 410,000 Wehrmacht troops poured into the Ardennes, a select group of Germans were given their last orders by SS Lieutenant Colonel Otto Skorzeny, who had led a mountaintop raid to rescue Italian dictator Benito Mussolini from imprisonment a year earlier.

For months, on Hitler's personal orders, Skorzeny had planned Operation Greif.

Its aim -- to sabotage Allied strongholds and cause turmoil behind enemy lines.

-Operation Greif was to be the work of the 150th Panzer Brigade.

Now, this was a very unusual unit.

The bulk of the unit, which was about 2,500 men strong, was to be equipped with German fighting vehicles, rather crudely mocked up to look like American fighting vehicles.

Painted that way, and also with American stars on the side.

They wouldn't have fooled anybody except at night.

But the most famous or infamous contingent of the 150th Panzer Brigade was its commando company.

-These commandos had been handpicked by Skorzeny to cross enemy lines.

-The men selected for the commando company of Operation Greif were selected in theory because they could speak American English well, although in practice very few of them actually spoke it perfectly.

Nevertheless, the net was cast quite far across all of the German armed services to try and find sufficient English speakers.

-On December 16, as the Ardennes battle began, Skorzeny's men, wearing captured American uniforms, slipped across enemy lines.

There, they set about creating havoc.

For two weeks, they directed Allied traffic down the wrong roads, destroyed ammunition stores, swapped road signs, and cut communication lines.

Despite their training, the Operation Greif men soon gave themselves away.

Teams of four traveled in the stolen jeeps when Americans allowed no more than three per jeep.

One unit asked for petrol rather than gas and were taken prisoner.

When questioned by their captors, the impostors' English was so bad that the Allies realized the presence of German saboteurs.

Furious, American General George Patton reported to Allied Commander in Chief General Dwight D. Eisenhower that the Germans were raising hell.

Word of the interlopers spread fast through the Allied troops, who were ordered to tighten their security.

-American sentries across the entire sector became hypervigilant in their efforts to uncover the rest, and they devised a number of tests, a number of questions to smoke out fake American soldiers.

Questions included things like, "What's Sinatra's first name?

What's the capital of Illinois?

Who is Betty Grable married to?"

Some sentries required the soldiers approaching them in jeeps to lower their trousers to see if they were wearing regulation U.S. Army underwear.

So really, within a pretty short space of time, the operation was coming apart.

-Many of the German infiltrators were captured and executed as spies.

Under interrogation, one of Skorzeny's men falsely claimed he was part of a team en route to Paris to murder Eisenhower.

-Eisenhower's headquarters in Paris was fortified, he was effectively kept under house arrest, and he put a body double in his car and had him driving around the city several times a day, ready to take a bullet for him if the Germans tried anything.

♪♪ -On January 3, 1945, the U.S. First Army began a counteroffensive... [Gunfire] ♪♪ ...and the surviving Operation Greif participants were withdrawn.

-Operation Greif really only caused a limited amount of practical disruption.

There was a bit of disruption of communications, there was a bit of misdirection of U.S. Army traffic, but not a great deal.

What it did do was spread a sense of panic bordering on paranoia behind the American lines.

-On January 25, the Allies claimed victory in the Battle of the Bulge.

They had crushed the last major German offensive of the war.

Their next target was Berlin.

Otto Skorzeny had infuriated the Allies with Operation Greif, but he soon met his match in the form of a Soviet spymaster named Pavel Sudoplatov.

By August 1944, the German front lines were being forced back from both east and west.

As the Allied vise tightened, Stalin authorized the use of captured Nazi soldiers as the bait in a lethal Soviet snare.

♪♪ On August 18, German high command received a radio message from a trusted Soviet agent.

Alexander Demyanov informed his Nazi handlers that a group of German soldiers were surrounded by Soviet forces near the Berezina River, desperately in need of help.

Unbeknownst to the Germans, Demyanov was a Russian double agent, acting on the orders of Pavel Sudoplatov, one of Stalin's most senior intelligence officers.

Demyanov's message was the first of a radio deception game.

The Soviet plan, codenamed Operation Berezino, was to create the illusion of a group of German resistance fighters trapped in Soviet territory.

Their intention was to drain Nazi resources by capturing any support that was sent to help this fictitious resistance.

-In the aftermath of Operation Bagration, large numbers of German forces are moving as pockets behind the Soviet advance.

The advances moved much faster than Germans can withdraw, and at the same time, they're not trying to stop and clear every forest.

Now, one of these groups, which was about 1,800 men, is finally reduced into a tiny pocket, and only about 200 prisoners of war are taken.

One of them is a guy named Scherhorn.

He is a commander, a German officer, and he is turned by Soviet intelligence.

Critically, some of his radio operators are also turned.

-Sudoplatov appointed Lieutenant Colonel Heinrich Scherhorn as a front for the operation.

-Scherhorn and his radio men are then dutifully communicating to the German high command, saying, "Yes, we're still here.

We have a huge number of men, with 2,000, and we're gonna keep fighting.

Send us supplies."

-The Germans made Scherhorn's men a top priority.

Otto Skorzeny, fresh from Operation Greif, was appointed to oversee a rescue mission.

On September 16, 1944, on Skorzeny's orders, a group of German commandos were dropped near Scherhorn's supposed location.

♪♪ Waiting was a welcome party of Soviet soldiers, who seized them and forced them to radio Skorzeny, asking for more men to be sent in to help Scherhorn's group reach German lines.

-So the Germans start sending dozens of flights, dropping supplies to Scherhorn.

They even send 2 million rubles.

The idea is this is now going to be the National Socialist resistance fighting behind the Soviet front.

This is all fanciful.

It doesn't exist.

And of course, everything that's being dropped in, including the operatives, are immediately being absorbed.

-Months into the operation, Sudoplatov's plan came perilously close to exposure.

The Germans contacted Scherhorn, telling him they were sending planes to airlift his men back to the German front.

If the planes landed, the Germans would discover that there were no men to rescue.

To protect his operation, Sudoplatov staged a battle between Scherhorn's group and Soviet soldiers.

In the chaos of the fake brawl, the runway lights were extinguished, preventing the German planes from landing and discovering the Russian ruse.

-The Soviet plan here is to consume German intelligence resources, and it's very successful.

In fact, the Germans continue to believe that Scherhorn is continuing his resistance right up until the end of the war.

-On Christmas Day, Hitler radioed messages of encouragement to Scherhorn's men.

A few months later, Scherhorn was given the Knight's Cross, Germany's highest military honor.

As the Allies closed in on Berlin, air supplies dwindled.

Germany was on its knees and had no more supplies to spare for Scherhorn.

The Russians captured 25 enemy agents, millions of rubles, and hoodwinked the Germans.

Operation Berezino was a Soviet triumph.

♪♪ Throughout the Second World War, despite the fact that the Soviet Union and America were united in their fight against Nazi Germany, a deep mistrust existed between the two nations.

-The Russians had never really given up this idea that the great adversary facing them was capitalism.

And America was the classic example of a capitalist system.

That meant that the Russians continued to innovate, think up new, original ways of gathering intelligence.

-As the war drew to a close, the Soviet Union presented America with a gift to celebrate their wartime allegiance.

In reality, however, this was no gesture of goodwill.

It was an act of Soviet espionage.

♪♪ ♪♪ On August 4, 1945, a group of Russian children presented a hand-carved, wooden replica of the Great Seal of the United States to W. Averell Harriman, the U.S. ambassador to the Soviet Union.

-There was a ceremony with all the pomp and significance you can imagine, where these small children passed over this wooden seal to Harriman.

And there's a photograph of him holding it up, looking very proud of this great symbol of the friendship between East and West.

-Harriman placed the plaque in the library of Spaso House, the American ambassadorial residence in Moscow.

He had no idea that the Great Seal was more than just a wall decoration.

Hidden under the eagle was a sophisticated Soviet listening device.

This bug was a passive-cavity resonator, meaning that it only became active when a radio signal of the correct frequency was sent to the device from an external transmitter.

If the Soviets suspected that an important meeting was scheduled in Spaso House, they parked an unmarked van close by and activated the bug.

When anyone near the device spoke, sound waves entered the bug through tiny holes beneath the eagle's beak... [Beeping] ...vibrating a membrane which transmitted speech to Soviet agents outside, listening in.

No bigger than a pencil, with no internal power source and no wires that could be discovered, the bug had a limitless lifespan and was undetectable except while activated.

For seven years, the bug lay hidden in plain sight inside the replica seal.

Soviet spies eavesdropped on American intelligence agents and congressmen as they discussed state secrets from within Spaso House.

Only by chance was the bug's presence finally discovered.

In 1951, a radio operator picked up the voice of the British Air attaché coming from Spaso House as he was monitoring Russian Air Force radio.

Clearly the Russians were spying on the residency, but repeated searches failed to locate a listening device.

On 10 September 1952, the Americans finally made a breakthrough.

A State Department security technician discovered the bug hidden inside the seal and sent it to Washington for analysis.

FBI technicians were baffled by the bug, and it became known as "The Thing."

When a British former MI5 scientific officer solved the puzzle of how the thing functioned, British and American scientists raced to replicate it for their own espionage activities.

The discovery of the bug was kept secret until a diplomatic crisis erupted years later.

In May 1960, the Soviets shot down an American reconnaissance plane in the Ural Mountains.

Furious, the Soviet Union demanded a U.N. Security Council meeting, where they accused the U.S. of spying.

♪♪ Henry Cabot Lodge Jr., the American ambassador to the U.N., responded by presenting the bug to both the Security Council and the press.

-...as well as the clandestine listening device.

-This, Lodge said, was a concrete example of Soviet espionage and proof that spying between the Soviet Union and America was mutual.

The fact that the world's leading superpowers were spying on each other reverberated across the globe.

When the school children presented Harriman with the replica seal in 1945, they had laid a foundation stone for the forthcoming Cold War.

-If it should ever be accepted that the Soviet Union can maintain a double standard whereby they have thousands of spies and subversive agents everywhere, while protesting one single, harmless observation flight, the free world would surely be in great and peculiar danger.

♪♪ -August 1945.

The United States dropped atomic bombs on Japan, decimating the cities of Hiroshima and Nagasaki.

This was the first time nuclear weapons had ever been used in war.

Days later, Japan surrendered.

The Second World War was over.

In the wake of the war, American intelligence revealed that an international network of Soviet spies had stolen the secrets behind the world's most dangerous weapon.

♪♪ ♪♪ On August 29, 1949, the Soviet Union successfully detonated its first atomic bomb at a remote testing site in Kazakhstan.

The news shocked the Western world.

The United States had believed it would be years before the Soviets would possess an atomic bomb of their own.

The Soviet atomic development was a fraction of the size of the American equivalent, the Manhattan Project.

-Despite the fact that the Russians were wartime Allies, they were not indoctrinated into the Manhattan Project.

This was very much an Anglo-American, Canadian to some extent, enterprise, with a number of other smaller countries.

Russia was not involved.

-The atomic bomb is too dangerous to be loose in a lawless world.

That is why Great Britain, Canada, and the United States, who have the secret of its production, do not intend to reveal the secret until means have been found to control the bomb so as to protect ourselves and the rest of the world from the danger of total destruction.

-Although the Soviets were not included in the Manhattan Project, that did not mean they were unaware of the program's progress.

-There's a sort of classic, ironic moment in all of this towards the end of the war, at the Potsdam Conference, where Harry Truman, who had only just become the president, who had only previously been told about the atomic bomb about a month or so beforehand, gave this sort of nudge, nudge, wink, wink to Stalin, saying, "We've got this great destructive weapon."

And Stalin had a completely blank poker face.

What we now know is that Stalin had known for years, long before Harry Truman did, that the Americans were building an atomic bomb.

And that's entirely thanks to Soviet intelligence.

-Towards the end of the Second World War, the world's major powers had started to compete for atomic supremacy.

-And so it became a race.

The British and Americans wanted to snatch any technology and any personnel, particularly the German scientists who were in hiding in Germany after Germany collapsed in May 1945.

We were already entering the Cold War.

-In response, throughout the 1940s, the Soviet Union recruited informants from within the heart of the Manhattan Project at Los Alamos, New Mexico.

-The espionage to do with the atomic bomb basically depended on idealistic, young scientists who wanted the Russians to have a nuclear chance or didn't want the West to have a monopoly on nuclear weapons and wanted a nuclear balance.

And those young scientists contacted friends who were in the Communist left, and they in turn contacted the embassy, the Russian embassy, where, of course, there were plenty of people undertaking espionage.

-By 1950, the Soviets had a web of agents dedicated to stealing atomic secrets from Britain and America.

On January 27, 1950, that web began to unravel.

Alerted by Venona, an American counterintelligence program decrypting Moscow's communications, British authorities arrested Dr. Klaus Fuchs in London on suspicion of spying.

-Klaus Fuchs was a German who had emigrated to the U.K. in the 1930s.

He was a Quaker.

He hated Nazism.

He hated fascism, everything it stood for.

He saw what was coming in the early stages of the 1930s, and he escaped to Britain.

He completed a doctorate.

And as war broke out, he was one of the leading physicists in the U.K. And so inevitably, he was then brought into the wartime efforts to build an atomic bomb.

He was sent over to Los Alamos in the United States, was a key part of the Manhattan Project, but the whole time was sending information to the Soviets.

-Under interrogation, Fuchs admitted passing technical drawings and data related to the design of the atomic bomb to Soviet Russia.

-He would go to a nearby town and would meet his contact, and they would go and have a coffee in a café or somewhere reasonably secluded, and Fuchs would pass over his information there.

-Fuchs' contact was Harry Gold, an American chemist and Soviet courier who was soon facing questioning.

-When he was put under pressure by the FBI, he revealed everything he knew about the espionage.

-Gold set the FBI on the trail of the second Los Alamos spy, David Greenglass, who, like Fuchs, worked on the atomic bomb.

Recruited by his brother-in-law, committed Communist Julius Rosenberg, Greenglass began handing over top-secret information in 1944.

Forbidden from removing anything from Los Alamos, he scribbled notes from memory, which his sister Ethel turned into neatly typed documents.

Ethel's husband, Julius, took the bundles of information to his Soviet contacts, arranging clandestine meetings by leaving notes in prearranged alcoves in New York cinemas.

By the summer of 1950, Greenglass, Gold, and the Rosenbergs had all been arrested.

♪♪ The American and British investigations exposed more than a dozen people who had passed atomic secrets to the Soviets.

But it is still unknown how many spies escaped undetected.

The atomic spies saved Russia months, if not years, of work.

Head of the Soviet atomic project, Igor Kurchatov, later said that Soviet espionage accounted for 50% of the project's success.

The American atomic monopoly that had begun with the bombing of Hiroshima in 1945 was over.

For the first time in history, the world was living under the threat of nuclear warfare.

The arms race that would define decades of the Cold War had begun.

♪♪ Throughout World War II, both sides used deception strategies of a scale and complexity which remains unmatched.

-Deception was critical to the Allied victory in World War II.

Deception involved disruption, distraction, decoying the enemy into doing things and making decisions that would bring about their defeat.

-The Second World War ushered in a new era of sophisticated espionage.

-And hot on the heels of the Second World War, is the Cold War.

And that's going to be another war in which intelligence is crucial.

The Second World War really was a watershed in that way.

It changes the character of war, and it changes the way that war is waged.

And that's not gonna change back.

-In its aftermath, as ally turned on ally, subterfuge, secrets, and spies would define the decades to come and shape the world we live in today.

♪♪