[Narrator] THE BIGGEST CONSTRUCTION PROJECTS OF WORLD WAR II, ORDERED BY HITLER TO SECURE WORLD DOMINATION.

NOW THEY SURVIVE AS DARK REMINDERS OF THE FUHRER'S FANATICAL MILITARY AMBITION.

THESE ARE THE SECRETS OF THE NAZI MEGA WEAPONS.

[Speaking German] [Narrator] 6TH JUNE, 1944.

THE D-DAY INVASION HAS BEGUN.

IN NORMANDY, 1,500 GERMANS FACE AN ALLIED FORCE OVER 150,000 STRONG.

[Speaking German] SOLDIERS SUCH AS TEENAGER FRANZ GOCKEL ARE RELYING ON BUNKERS LIKE THESE TO REPEL THE INVASION FORCE.

BUNKERS THAT FORM AN EXTRAORDINARY 3,000 MILES OF FORTIFICATION KNOWN AS THE ATLANTIC WALL.

THE NAZIS BUILT THIS MEGA STRUCTURE ALONG EUROPE'S WEST COAST TO PROTECT HITLER'S EMPIRE FROM AN ALLIED INVASION.

DR PETER LIEB, FORMER GERMAN OFFICER AND WAR STUDIES EXPERT, HAS EXAMINED THE WALL'S CONSTRUCTION.

There were bunkers all over France along the coastline, in Belgium and the Netherlands.

It is the most gigantic fortification that were ever built in history.

FOUR YEARS BEFORE D-DAY, WHEN HE FIRST GUN POSITIONS WERE CONSTRUCTED, THEIR PURPOSE WAS NOT TO DEFEND BUT TO ATTACK.

HITLER'S ARMY HAD CONQUERED BELGIUM, LUXEMBOURG AND THE NETHERLANDS IN LESS THAN THREE WEEKS IN THE SPRING OF 1940.

FRANCE SURRENDERED ON 22ND JUNE.

[Crowds cheering] BATTLEFIELD ARCHEOLOGIST, DR TONY POLLARD, SPECIALIZES IN THE NAZI DEFENSES OF THE SECOND WORLD WAR.

We have most of Europe falling to the might of Nazi Germany and to the Blitzkrieg, and really one of the only opponents still standing against them is the little island of Britain.

HITLER ORDERS HIS GENERALS TO CONSTRUCT MASSIVE GUN POSITIONS AT CALAIS WHERE THE FRENCH COAST IS NEAREST TO BRITAIN.

THE JOB OF BUILDING THEM FALLS TO ONE MAN... - Heil Hitler!

- Heil Hitler!

[Officer] Attention.

These are the Fuhrer's latest orders.

The coast must be armed with as many heavy guns as possible.

FRANZ XAVER DORSCH IS A CHIEF ENGINEER OF THE TODT ORGANIZATION, GERMANY'S BIGGEST ENGINEERING COMPANY.

These guns are to be enclosed in concrete.

DORSCH AND HIS COLLEAGUES ARE EXPERTS IN LARGE-SCALE CONSTRUCTION.

THEY PIONEERED NAZI GERMANY'S FAMOUS AUTOBAHNS, THOUSANDS OF MILES OF ROADS THAT STILL EXIST TODAY.

I will personally direct the work.

Is that all clear?

DORSCH MOBILIZES 9,000 MEN TO BUILD TWENTY LARGE-CALIBER GUN POSITIONS IN CALAIS.

IN THE SKIES OVERHEAD, THE GERMAN AND ALLIED AIR FORCES ARE FIGHTING FOR AIR SUPREMACY.

PROTECTING THE GIANT GUNS FROM ALLIED AIR ATTACK WILL REQUIRE MILLIONS OF TONNES OF CONCRETE.

Concrete is, I suppose, an unpromising product.

It's just natural geology that's bound together in a powdered form with water.

But the Germans have learned that it can take a heck of a pounding, and so they learned to work with it on a huge scale.

BUILDING WITH CONCRETE ISN'T NEW, BUT THE SCALE OF THE NAZI STRUCTURES IS EXTRAORDINARY, WITH WALLS AND CEILINGS 10-FEET THICK, ALL REINFORCED WITH A LATTICE OF STEEL.

[Pollard] Then, against that, they put up wooden shuttering.

On both sides, that shuttering creates a mould.

What you then do is simply pour in your concrete through the top.

When you take your shuttering away, you've got a concrete structure.

EACH OF THE TWENTY GUN POSITIONS REQUIRE OVER 40,000 TONS OF CONCRETE.

ENGINEERED TO BE INDESTRUCTIBLE, MANY STILL SURVIVE TODAY.

Visiting these bunkers, it's like a step back in time.

ARTHUR VAN BEVEREN IS AN EXPERT IN THE ATLANTIC WALL AND HAS BEEN EXPLORING ITS RUINS SINCE HE WAS A BOY.

These walls are 3.5 meters thick and if you look at this corner, you can still see the shape of the wood in the concrete.

It left its marks in the concrete while it was being poured.

The huge dome-like building is the actual gun emplacement.

which the 38-cm gun was beneath.

On this side, we have the crew rooms, kitchens, first aid and ammunition.

[Beveren] A very atmospheric place, back then.

And I think it still is.

THE SHELLS ARE 5.5 FEET LONG AND WEIGH 1,800LBS.

THEY ARE SO BIG THAT THEY HAVE TO BE MOVED INSIDE ON A SYSTEM OF OVERHEAD RAILS.

So you can see the rail from the outside, going through this gap up here.

But you can still see a part left in this gap.

It was used to transport the ammunition.

This is now just an empty gap, but 70 years ago there would have been a door here.

And there was a table up here.

The ammunition was prepared, lain on the table, and on this side there was a little train driving along the gun.

The ammunition was put on the little train and transported to the gun.

WITH A RANGE OF 40 MILES, THE GUNS WERE ABLE TO BATTER THE BRITISH COAST.

From here on a clear day, you can see Britain on the other side of the Channel.

Britain is only 36km away, and these guns could reach 30km inside Britain.

THE BOMBARDMENT BEGINS IN AUGUST 1940.

THEY DESTROY OVER 10,000 HOMES AND KILL HUNDREDS OF CIVILIANS ON MAINLAND BRITAIN.

BUT OVERHEAD THE GERMAN AIR FORCE HAS LOST THE AERIAL WAR.

SO, IN SEPTEMBER, HITLER CALLS OFF HIS PLANNED INVASION.

Britain really isn't worth his time.

It's a tiny place, it doesn't have many resources, he's playing a much bigger game.

Soviet Russia is massive, that's where he turns his attention.

So he cancels all the activity in the west, and in 1941 he invades Russia, Operation Barbarossa.

IT IS A MASSIVE STRATEGIC BLUNDER.

THE SOVIETS PUT UP TOUGH RESISTANCE.

GERMANY'S ARMIES GET BOGGED DOWN IN A BRUTAL CAMPAIGN ON THE EASTERN FRONT.

THEN, IN DECEMBER, HITLER'S WORST FEAR BECOMES A REALITY: AMERICA JOINS THE WAR.

Hitler knew this was coming and he knows it's very bad news.

Not only is he heavily engaged in Russia to the east, he now knows that Britain has got a very strong ally to the west in the form of the USA.

NOW THE WESTERN SEABOARD OF THE NAZI EMPIRE LOOKS WEAK AND VULNERABLE.

FOR THE FIRST TIME HITLER'S ATTENTION TURNS TO DEFENSE.

And so he puts out his famous Directive 40, which is basically rattling the cage and saying, "Enough, we need to get our act together."

And in a series of bullet points, he states, in no uncertain terms, what is expected of his fighting forces and of his engineering organizations.

THE TWENTY GUN POSITIONS BUILT AROUND CALAIS TO ATTACK BRITAIN NOW BECOME PART OF A DEFENSIVE ATLANTIC WALL THAT WILL STRETCH ALL THE WAY FROM SPAIN TO NORWAY.

FOR GERMANS BACK IN BERLIN, UNAWARE THAT THE WAR IS GOING BADLY, THESE FORTIFICATIONS ARE PORTRAYED AS A TRIUMPH.

NEWS REELS PROUDLY BOAST OF THEIR AWESOME FIREPOWER, AND NO ONE IS FOLLOWING PROGRESS MORE AVIDLY THAN 16-YEAR-OLD FRANZ GOCKEL.

[German news voiceover] [Gockel] 'I'd seen so much reported about the Wall 'in the newsreels that I was sure we'd be invincible.'

[German news voiceover] THESE PICTURES ARE POWERFUL PROPAGANDA.

BUT WHAT HE DOESN'T KNOW IS THAT HE WILL SOON SEE THE ATLANTIC WALL FOR HIMSELF, AND ON D-DAY HIS LIFE WILL COME TO DEPEND ON IT.

AT 3,000 MILES LONG, THE NAZI'S AIM TO BUILD A DEFENSIVE LINE NEARLY TWICE THE LENGTH OF AMERICA'S EAST COAST.

AND THEY PLAN TO MAKE THE STRUCTURE ABLE TO WITHSTAND ANY ALLIED ATTACK.

BUT IN SPRING 1942, THE WALL, THE BRAIN CHILD OF HITLER, IS NOTHING MORE THAN A HANDFUL OF GUN POSITIONS.

[Lieb] The Atlantic Wall is very much a product of German propaganda, and should give confidence to the Germans that they are prepared to defeat the Allies.

In reality, it was only a string of pearls.

HITLER KNOWS AN ALLIED ATTACK WILL COME, BUT THE QUESTION IS: WHERE?

THERE ARE DEFENSIVE HOLES ALL ALONG THE WESTERN SEABOARD.

ACROSS THE CHANNEL, BRITISH PRIME MINISTER, WINSTON CHURCHILL, WANTS TO FIND THESE WEAK POINTS.

PATRICK BURY IS A FORMER BRITISH ARMY INFANTRY CAPTAIN AND EXPERT IN MILITARY STRATEGY.

How does Churchill keep the morale of the nation high and keep the initiative, keep the Nazi's guessing where they are going to land?

He doesn't have many resources, he doesn't have many troops, one thing he can do is some strategic raiding.

CHURCHILL ORDERS A SERIES OF COMMANDO RAIDS TO PROBE THE ATLANTIC WALL.

THEY WANT TO DESTROY NAZI BASES AND FIND OUT WHERE THEY COULD LAND AN INVASION FORCE, SO THEY TARGET RADAR STATIONS AND HARBORS.

[Bury] They pick the port of St Nazaire, which has got one of the largest dry docks on the western Atlantic approaches.

The idea here is to get a battle ship disguised as a German battleship, pack it full of commandos and explosives and then ram it into the dry dock at night.

THIS DARING RAID IS A GREAT SUCCESS, THE DOCK IS OUT OF ACTION FOR THE REST OF THE WAR.

BUT THE CAPTURE AND EXECUTION OF HUNDREDS OF ALLIED TROOPS FROM ATLANTIC WALL RAIDS HAS TAUGHT CHURCHILL A VALUABLE LESSON.

The Allies drew the conclusion: "In future we mustn't land any more at harbors, "because they are too strongly fortified."

The Germans drew the completely opposite conclusion out of that and thought: "If the Allies come again, they'll try it at a harbor."

So what did they do?

They fortified particularly the harbors.

HITLER'S DECISION NOT TO INVADE BRITAIN IS RETURNING TO HAUNT HIM.

HE KNOWS THE COMMANDO RAIDS ARE JUST THE BEGINNING.

HE BECOMES FIXATED WITH FORTIFYING HARBORS, EVEN AS FAR NORTH AS NORWAY.

MASSIVE AMOUNTS OF MEN AND RESOURCES ARE SENT TO DEFEND THE NORWEGIAN COAST ALL THE WAY TO THE ARCTIC.

Norway was very important initially, because of its location.

There's a lot of iron ore coming out of Sweden, and it's taken aboard ship in Norwegian ports.

IRON ORE IS VITAL TO THE GERMAN WAR EFFORT, PROVIDING THE STEEL IN HITLER'S BOMBS, TANKS AND BUNKERS.

THE NORWEGIAN SUPPLY LINE MUST BE DEFENDED.

SO THE GERMAN ENGINEERS REMOVE A 900-TON NAVAL GUN FROM ITS BATTLESHIP AND MOVE IT TO ORLAND, TO PROTECT THE PORT OF TRONDHEIM.

ASTONISHINGLY, IT STILL SURVIVES TO THIS DAY.

Essentially, this is a ship built on land, built inside this mountain.

A deep shaft five levels deep was cut into the mountain, filled up with concrete, and the turret was placed inside that shaft.

THE OCCUPYING GERMAN FORCES IN NORWAY USE PRISONERS OF WAR TO DIG A 36-FOOT DEEP HOLE THROUGH THE SOLID ROCK.

IT HAS TO BE LINED WITH CONCRETE BEFORE THE TURRET CAN BE REBUILT INSIDE.

The guns were put in parts.

Eighty train loads of parts went to Trondheim, and from Trondheim onto boats up to the island.

The three guns are the only thing you can see on the outside but the actual bunker is inside this mountain.

When you look around it, it's solid engineering everywhere.

It's all separate pieces working together to keep this machine going, like a monster really.

The black floor we see here is the actual tower from the ship.

This part is really the bunker, the shaft into the mountain.

This part will stand still, so this is concrete and this is a five-floor deep shaft from a naval ship.

JUST AS WHEN IT WAS ON A SHIP, THE MASSIVE GUN NEEDS TO ROTATE.

The whole turret is resting on these ball bearings all around us.

Really very heavy, really very heavy.

I guess about 40, 50 kilos.

And they're all around, resting in the reel around the shaft.

138 STEEL BALLS CARRY THE WEIGHT OF THE 900-TON GUN AND ALLOW IT TO TURN SMOOTHLY.

THE SHELL AND PROPELLANT ARE STORED FIVE LEVELS BELOW THE GUN.

We've got three different kind of ammunition here.

We've got high-explosive shells, armored piercing shells, and even shells with time fuses.

TO MANEUVER THESE 600 60-POUND SHELLS, THE NAZI ENGINEERS DEVISE AN INGENIOUS HYDRAULIC LIFT SYSTEM.

The shells will come right out of the walls, the ammunition rooms, slide over here, roll onto this table, roll on further, and when it finally reaches up here, you could traverse the shell... ...up to the lift.

Of course, normally it would be hydraulically operated.

THE AMMUNITION IS LIFTED FIVE STORIES UP TO BARREL LEVEL, READY TO BE FIRED.

The effective range of these guns is about 37km, and that's as far as the eye can see.

From the top in Norway all the way down to the south of France, you can find the same kind of bunkers.

So it's not just concrete blocks, it's massive ships on land.

ALONGSIDE THE HEAVILY DEFENDED BATTERIES AT THE PORTS OF MOVIK, CHERBOURG, BREST AND THE ISLAND OF JERSEY, A FORMIDABLE DISPLAY OF DEFENSE IS TAKING SHAPE.

BUT HITLER REALIZES THIS IS STILL NOT ENOUGH.

BETWEEN THE PORTS, VAST STRETCHES OF COAST REMAIN UNDEFENDED.

Hitler puts out another order that 15,000 bunkers are to be built along a coastline stretching 3,000 miles, and they are to be manned by 300,000 troops.

HITLER WANTS A CONTINUOUS LINE OF FORTIFICATIONS TO DEFEND THE 3,000-MILE COAST, MORE THAN THREE TIMES THE LENGTH OF CALIFORNIA.

AND HE WANTS IT FINISHED BY MAY, 1943, IN JUST SEVEN MONTHS' TIME.

Speer describes Hitler as spending his evenings designing concrete bunkers.

And he had locked in his desk a series of maps of the western seaboard on which he would plot where fortifications would be.

THE WALL NOW BECOMES HIS OBSESSION.

These designs ideally meet all the requirements of a frontline soldier.

During this winter, with fanatical zeal, a fortress must be built which will hold in all circumstances.

Heil Hitler!

[Inaudible whispering] THE TASK OF MAKING HITLER'S WALL A REALITY FALLS TO HIS CHIEF ENGINEER DORSCH.

That is the absolute maximum volume of construction we can handle, we cannot handle any more!

DORSCH MIGHT HAVE CONCERNS BUT NOBODY REFUSES THE FUHRER.

CONSTRUCTION TEAMS TRY AND MEET HITLER'S DEMANDS, FOCUSING THEIR EFFORTS ON AREAS WHERE THEY THINK THE INVASION MIGHT COME, SUCH AS THE BEACHES OF WISSANT, CLOSEST TO THE BRITISH MAINLAND.

We're now standing on top of an anti-tank gun bunker.

It was built here in March, 1943, and it's type 631.

The Germans designed about 500 different types of bunkers.

The Atlantic wall was not one line of bunkers, but it was made out of several strong points with open spaces in between.

WITH THE BRITISH AIR FORCE IN CONTROL OF THE SKIES, THE 475 SOLDIERS HERE LIVE IN CONSTANT FEAR OF ATTACKS.

During an air attack, with soldiers running around, they could see the S and the T, which means this bunkers has walls 2-metres thick.

That means they are safe in any air attack.

Just above the S-T sign, we've got the air inlet.

This posed a threat because any enemy could throw in a grenade or something like that.

This part is interconnected with this one, and there is only one pipe going in.

If you throw a grenade inside this part, you'll see what happens...

It comes out at the bottom again, so the bunker has fresh air, but it's protected against any attack.

WHEN AN INVASION COMES, IT WON'T JUST BE AIR ATTACK AND INFANTRY.

LARGE TANKS WILL ROLL UP THE BEACH, AND THIS BUNKER HOUSES THE GUN THAT CAN STOP THEM.

So we are now in the most important room of this bunker, because this is the room where the gun used to be.

The anti-tank gun, 4.7cm, of Czech origin.

THE MEN STATIONED HERE SPENT MONTHS PREPARING FOR AN INVASION.

THE FIRING RANGE FOR EVERY POTENTIAL TARGET WAS CAREFULLY PRACTICED.

This is a really cool feature in this bunker.

It actually still has these numbers on the plate next to the gun.

And they tell the crew certain points on the landscape how far away they are from the bunker.

We have a church or a house near the beach, so they can measure from these points how to aim the gun.

THE BUNKER WAS DESIGNED TO BE INDESTRUCTIBLE, BUT THERE IS STILL THE RISK OF BEING BURIED ALIVE BY THE DEBRIS OF A BATTLE.

We have another exit here, it's the escape shaft.

You have to get through the brick wall.

You have to dig through four meters of pebbles and then you can get out via this shaft on the side of the bunker.

THE CREW LIVED HERE NIGHT AND DAY FOR TWO YEARS BEFORE THE INVASION CAME.

German veterans and also Allied veterans who entered the bunkers after liberation talk about the smell.

It could differ from bunker to bunker, I guess, but it would definitely be smelly up here.

Walking through one of these structures today, I might as well be walking through Stonehenge, because these are very enigmatic structures.

But if you were to see them operating, with all the hardware, all the guns and the men inside them, I think you'd be fairly impressed at what these things have developed into: very, very frightening fighting machines.

ONLY 30% OF THE REQUIRED BUNKERS ARE FINISHED BY HITLER'S DEADLINE OF MAY, 1943.

AS CHIEF ENGINEER XAVER DORSCH KNOWS, HITLER WILL BLAME HIM.

We have handed over 9,671 ready-to-occupy bunkers and the concrete work has been done for another 1500!

BUT DORSCH LACKS THE RESOURCES THAT HE NEEDS TO INCREASE PRODUCTION.

THE WAR HAS NOW DRAGGED ON FOR FOUR YEARS AND THE GERMANS ARE RUNNING OUT OF MATERIAL, MONEY AND MEN.

And Hitler gets very irritated when resources keep bleeding away from the western seaboard, from his Atlantic Wall, to the war in the east.

He puts out an edict and says: "Nobody moves anything or anyone from the Atlantic Wall "without my prior and direct permission."

OCTOBER, 1943, COLLEVILLE, NORMANDY.

NEW CONSCRIPT PRIVATE FRANZ GOCKEL, JUST 17, ARRIVES AT HIS SECTION OF THE WALL.

THE PROPAGANDA FILMS THAT HE'S WATCHED BACK IN GERMANY SPOKE OF GIANT FORTRESSES AND GUN POSITIONS.

BUT HE'S IN FOR A SHOCK.

[Gockel] 'Imagine my surprise, 'arriving at the beach in Normandy, 'and there weren't any protective bunkers.'

HITLER BELIEVES THE ALLIED INVASION WILL LAND AT CALAIS, THE CLOSEST FRENCH PORT TO GREAT BRITAIN.

THAT'S WHERE HIS ATLANTIC WALL IS AT ITS STRONGEST.

FEW EYES ARE ON THE SHORES OF NORMANDY.

FRANZ GOCKEL'S DIARY RECORDS HAPPY DAYS SPENT SWIMMING AND PLAYING ON THE SANDS AT COLLEVILLE, A STRETCH THAT WILL COME TO BE KNOWN AS OMAHA BEACH.

[Gockel] 'France is a beautiful country, 'and I see the sea every day.

'I don't really have that much to do.'

[Lieb] It was definitely a cushy life compared to the horrors of the Eastern front.

The men here felt very happy that they were here in France.

NOVEMBER, 1943: EVENTS IN RUSSIA ARE GOING FROM BAD TO WORSE.

THE GERMANS HAVE BEEN FORCED INTO RETREAT BY A POWERFUL SOVIET ARMY.

The Germans lost on average 2,000 men killed in action each day, and that was since June, 1941.

HITLER AND HIS GENERALS NOW FACE A CRISIS.

THEY HAVE TO FIGHT ON TWO FRONTS.

MILLIONS OF THEIR SOLDIERS TIED UP IN THE EAST, AND 3,000 MILES OF COASTLINE TO DEFEND IN THE WEST.

THE NAZIS HAVE POSTED 300,000 SOLDIERS TO THE BUNKERS OF THE ATLANTIC WALL, BUT THEY ARE INEXPERIENCED TROOPS.

[Lieb] The crew here of the bunkers were mainly young soldiers 17 or 18 years old, or older family fathers in their late 30s.

The guys in their early 20s, mid-20s, the best soldier material as you would call it in military terms, were mainly on the Eastern front.

THE NAZI HIGH COMMAND ARE COUNTING ON MILLIONS OF TONS OF CONCRETE AND STEEL TO MAKE THE DIFFERENCE AND KEEP THE ALLIES AT BAY.

[Lieb] You can say that the bunkers made the soldiers better fighters.

You could be a bit overweight, you could be a bit over aged, but you could still pull the trigger on a machine gun.

BUNKERS MIGHT COMPENSATE FOR THE PROBLEM OF INEXPERIENCED TROOPS.

BUT ON AVERAGE THERE ARE STILL ONLY 100 GERMAN SOLDIERS TO DEFEND EACH MILE OF COAST.

AND ONLY 50% OF HITLER'S IMPREGNABLE WALL HAS BEEN COMPLETED.

This is hopeless!

I am the greatest builder of fortifications of all time and this is all I get!

BY NOVEMBER, 1943, HITLER RUNS OUT OF PATIENCE WITH THE SLOW PROGRESS OF WALL CONSTRUCTION.

HE APPOINTS A NEW COMMANDER TO TAKE CHARGE, A MAN WHOSE LEGENDARY TOUGHNESS IN BATTLE MIGHT MAKE UP FOR THE WEAKNESSES OF THE WALL: FIELD MARSHALL ERWIN ROMMEL.

[Officer] Quick, quick!

Fall in!

ROMMEL IMMEDIATELY SETS ABOUT INSPECTING THE ENTIRE LENGTH OF THE ATLANTIC WALL.

HE HAS BEEN FIGHTING THE ALLIES IN NORTH AFRICA FOR TWO YEARS.

ROMMEL IS A MASTER OF ATTACK AND DEFENSE.

WHAT HE SEES IN NORMANDY SHOCKS HIM.

Rommel came to this place here on January, 1944, and when he looked at the conditions and how the defense preparations had gone, he was very upset.

He was saying, "You've been here for three years "and what have you done?

Nothing!"

GERMAN PLANNERS BELIEVE THAT THE ALLIES ARE UNLIKELY TO CHOOSE IT AS AN INVASION SITE BECAUSE IT LACKS A PORT, SO FEW BUNKERS HAVE BEEN BUILT HERE.

BUT ROMMEL SEES SOMETHING THEY CAN'T.

[ROMMEL] This beach looks similar to the Bay of Salerno in Italy that the Allies invaded.

It must be instantly secured against Allied landings.

If the British once get a foothold on dry land, they can't be thrown out again.

ROMMEL KNOWS THIS BEACH NEEDS TO BE DEFENDED.

IF THE ALLIES LAND HERE, THE NAZIS COULD LOSE THE WAR.

ACROSS THE CHANNEL, 150,000 ALLIES TROOPS ARE MASSING.

THE ATLANTIC WALL IS ABOUT TO FACE THE ULTIMATE TEST, AND AT OMAHA BEACH, FRANZ GOCKEL WILL FACE THE FULL ONSLAUGHT OF THE INVASION.

BY JANUARY, 1944, SOVIET RUSSIA IS STILL PUSHING THE NAZIS BACK IN THE EAST.

AND IN THE WEST, HITLER'S ATLANTIC WALL IS FAR FROM COMPLETE.

FIELD MARSHALL ROMMEL FACES AN ENORMOUS CHALLENGE TO IMPROVE THE QUALITY OF THE DEFENSES, AS HE RECORDS IN HIS DIARY... [Rommel] 'These fortifications are the work of an engineer 'who is neither strategically proficient 'nor has any knowledge of war.'

ROMMEL'S EXPERIENCE FIGHTING THE ALLIES HAS TAUGHT HIM THAT HOLDING OF AN INVASION WILL REQUIRE METICULOUS PLANNING, AND HE HAS A VERY CLEAR STRATEGY.

Rommel believes that an enemy invasion has to be smashed if not at sea, on the beach.

If the enemy get off the beach, he thinks the game is over.

TO DEFEND EVERY BEACH, ROMMEL WANTS THOUSANDS MORE SMALL BUNKERS FOR INDIVIDUAL SOLDIERS ARMED WITH HEAVY MACHINE GUNS.

THEY WILL BE QUICKER TO BUILD BUT THERE IS STILL THE PROBLEM OF MANPOWER.

As the war develops, they don't have the spare manpower within Germany, and they basically draft in people of these countries, the Poles, the Czechs, you name it, the French, people from concentration camps, allied Prisoners of War, all of which is massively inhumane.

Thousands and thousands of them die in these construction projects through bad diet and bad treatment, and it just becomes slave labor.

32,000 CIVILIANS ARE FORCED INTO CONSTRUCTION, A BRUTAL BUT EFFECTIVE PLAN.

BUNKERS ARE BEING CONSTRUCTED ALL ALONG THE 3,000-MILE NAZI COAST, CLUSTERED IN GROUPS KNOWN AS A WN'S.

A WN is a Widerstandsnest, which translates into English as "resistance nest".

You can say it is more or less a strong point, but a series of strong points, interconnected.

IN NORMANDY, GOCKEL AND 30 OF HIS COMRADES LIVE IN A STRONGPOINT THAT STILL EXISTS TODAY.

We can see here the small room, probably for the NCOs, Here is the accommodation block for the other ranks, amongst them was also 18-year-old Franz Gockel.

But of course the soldiers did not stay here all the time, they were on guard, they had to build up the constructions, there was general training, military training.

GOCKEL'S STRONGPOINT IS AT THE EAST END OF A NORMANDY SHORELINE THAT WILL BECOME INFAMOUS: OMAHA BEACH.

TO DEFEND IT, THEY HAVE 13 GUN POSITIONS, INCLUDING TWO ANTI-TANK GUNS AND THREE MORTARS.

THE LARGEST BUNKERS HAVE A DIRECT LINE OF FIRE TO THE BEACH.

[Lieb] This one here had a 75mm Czech gun.

What is interesting about this bunker is here, the embrasure.

The embrasure protected the Germans, the muzzle flash could not be seen from the seaside.

THE EMBRASURE, OR LARGE WALL, ON THE OCEAN SIDE OF THE BUNKER HIDES THE FLASH OF THE FIRING GUN FROM AN INVADING FORCE, MAKING IT HARDER FOR THE ENEMY TO SEE THE POSITION.

When we also look at the gun, its arcs of fire, they are not pointing towards the sea, they are pointing towards the beach.

This perfectly reflects German doctrine of how to fight the invasion.

THE GUNS WORK IN PAIRS, TARGETING THE BEACH WITH DEADLY ARCS OF CROSS-FIRE.

THIS TACTIC CREATES AN AREA OF MAXIMUM FIREPOWER KNOWN AS A KILLING ZONE.

The killing zone is basically the area where the enemy is going to bring the maximum effect of all their weapon systems in the most condensed space, to inflict the maximum amount of casualties on the enemy, in this case, the Allies.

What you've got over here is two positions.

They've got machine guns, mortars.

And over here another position, machine guns, mortars.

some larger caliber rounds as well.

And the reason this box is here is because the Allies are trying to get up that draw and off the beach.

DEFENDING THIS STRETCH OF OMAHA BEACH IS VITAL FOR THE GERMANS TO THROW BACK AN ALLIED INVASION.

GOCKEL'S JOB IS TO MAN A MACHINE GUN AND HIS POSITION COVERS THIS KILL ZONE.

This is Gockel's position.

Today it's only a hole in the ground.

Back in 1944, it had a machine gun, it was a covered position, and also had two switches for a flame thrower.

GOCKEL'S BUNKER IS FINISHED BY MAY, 1944, ALONG WITH THOUSANDS MORE THAT PROTECT THE COAST FROM NORWAY TO THE SPANISH BORDER.

BUT ROMMEL STILL ISN'T SATISFIED.

THE BUNKERS ALONE ARE NOT ENOUGH.

HE ALSO WANTS OTHER TYPES OF DEFENSIVE STRUCTURE TO HELP REPEL AN ALLIED INVASION.

And what Rommel does, he uses the experiences he's gained in North Africa to bring about dramatic changes.

And one of those involves the laying of massive minefields.

HE ORDERS THE LAYING OF 50 MILLION MINES ALONG THE FRENCH COAST, AT SEA AND ON THE BEACH.

IN ADDITION, HE WANTS THE BEACHES FILLED WITH OBSTACLES, ROW AFTER ROW, LITTERING THE BEACH, TO CREATE IMPENETRABLE LAYERS OF DEFENSE.

THE FIRST LINE, BY THE LOW TIDE MARK, ARE STEEL BARRIERS KNOWN AS BELGIAN GATES.

You've got Belgian gates put along here.

The idea behind these Belgian gates is to block the landing craft, infantry and tanks, and basically hold them as far back down the beach as they can.

BELGIAN GATES CREATE A BARRIER TO SLOW DOWN INFANTRY AND TANKS, GIVING THE GERMANS MORE TIME TO KILL THEM.

IN CASE THE ALLIES ARRIVE AT HIGH TIDE AND SAIL OVER THE BELGIAN GATES, ROMMEL DEVISES ANOTHER SURPRISE.

Right here is where they have the ram logs.

Think about telegraph poles cut, raised above my head at a 30-degree angle, couple of other ones supporting it down here.

At the end of these you have basically saw blades to rip the bottom out of the landing craft if the Allies come in at high tide.

BUT EVEN THAT'S NOT ENOUGH.

THE GERMANS USE ABSOLUTELY ANYTHING THAT MIGHT DISRUPT AND DELAY THE LANDING FORCE.

Here you have the third belt, what they call Czech hedgehogs.

They're steel structures set at angles like this basically to disrupt anyone that's coming up the beaches.

AND IF THE LANDING CRAFT FINALLY MAKE IT ON TO THE BEACH, THESE ARE THE LAST LINE OF DEFENSE TO STOP ALLIED TANKS IN THEIR TRACKS.

So this is a steel-encrusted concrete tetrahedron, and this is one of the last obstacles on the obstacle plan for defending the beaches.

You can imagine a whole load of these all across the beach interlinked every five meters.

A tank's going struggle against this, it's so sturdy.

It's gonna turn the tank which way the tracks go.

Especially thin-tracked tanks will slip off the side.

BY JUNE, 1944, ROMMEL IS STILL TRYING TO COMPLETE GERMAN DEFENSES ALONG THE ATLANTIC COAST.

MEANWHILE, ACROSS THE CHANNEL, THE ALLIED TROOPS ARE READY.

HITLER'S 3,000-MILE ATLANTIC WALL HAS COST BILLIONS OF REICHSMARKS AND CONSUMED MILLIONS OF TONNES OF CONCRETE, BUT IT'S STILL RIDDLED WITH HOLES.

[Lieb] Rommel promised Hitler that he'd have finished everything by May, 1944, but it was still incomplete.

So many of the bunkers on the Atlantic Wall were lacking guns, or were lacking men, or were lacking barbed wire and minefields.

JUNE 5TH, GOCKEL SPENDS THE DAY PATROLLING THE CLIFFS ABOVE OMAHA BEACH.

UNKNOWN TO HIM, JUST OVER THE HORIZON, THOUSANDS OF BRITISH, CANADIAN AND AMERICAN TROOPS HAVE PUT OUT TO SEA TO START AN INVASION.

At two o'clock in the morning on 6th June, the 7th Army gave the alert level 2.

This was the highest alert level in the German army.

And immediately the men from the artillery regiment, and in this case from the 1st Company, moved in to their positions here at WN62.

[Air raid sirens wailing] Wake up!

Get up!

Get up!

This is for real!

The Americans are parachuting in just 30km away!

[Gockel] 'There was an alarm call, 'but none of us believed it.

'We'd had so many in the past weeks 'that we no longer took it seriously.'

[Officer] You, too, Gockel!

Get out!

[Gockel] 'We ran to our positions.

'Machine guns, heavy guns and mortars were prepared.'

GOCKEL AND HIS COMRADES BELIEVED THE INVASION WOULD COME AT A MAJOR PORT LIKE CALAIS.

NEVER DID THEY IMAGINE THAT IT WOULD HAPPEN HERE AT THEIR BEACH.

Has Gockel got ammunition?

Well, go and check!

Hitler and a lot of others were fairly convinced that it would have to be a major port, because they would have to get their materiel ashore.

Little did they know that the Allies had counted that, they had come up with the Mulberry harbors.

THE ALLIES INVENT AN INGENIOUS WAY OF AVOIDING THE HEAVILY FORTIFIED PORTS.

THEY BUILD THE WORLD'S FIRST FLOATING HARBOR, KNOWN AS THE MULBERRY HARBOR AND TOW IT TO NORMANDY.

Gockel, do you need ammunition?

Yes.

Good luck.

[Gockel] 'I tried to concentrate on my weapon 'to take my mind off what was happening.'

[Shouting in German] Normally a German machine gun should be manned by two soldiers.

Here, we had only one man per machine gun.

ALLIED BATTLESHIPS BEGIN A FULL-SCALE BOMBARDMENT OF THE GERMAN POSITIONS.

GOCKEL'S SURVIVAL NOW RESTS ON WHETHER THE REINFORCED CONCRETE OF HIS BUNKER IS TOUGH ENOUGH.

[Gockel] 'Heavy caliber shells continued 'to slam into the earth.

'Howling and hissing through the air.

'They hit against the concrete and ground with a thud.'

GOCKEL'S BUNKERS WITHSTANDS THE ONSLAUGHT, BUT IT'S JUST THE BEGINNING.

WHEN THE ALLIED FORCES LAND, THEY'RE MET WITH A HAIL OF MACHINE GUN FIRE.

JUST 500 GERMANS HAVE TO DEFEND A FOUR-MILE BEACH AGAINST 35,000 AMERICANS.

THE ULTIMATE TEST OF THE ATLANTIC WALL HAS BEGUN.

The Germans are firing with each weapon they've got available here.

With their flame throwers, with their machine guns, with their field guns, with their artillery from further inland.

This was when the German fire power was the biggest.

OMAHA IS JUST ONE OF FIVE INVASION BEACHES.

150,000 AMERICAN, CANADIAN AND BRITISH TROOPS ARE LANDING ALONG THE NORMANDY COAST.

AND THE ENORMOUS ATLANTIC WALL IS BEGINNING TO CRACK.

100 MILES AWAY, THE GERMAN ARMORED RESERVE OF TANKS ARE WAITING.

IF THEY ARE CALLED UP TO PLUG THE GAPS, THERE'S STILL A CHANCE THAT THE ALLIES CAN BE THROWN BACK.

BUT THERE'S A PROBLEM.

Hitler was asleep and no one dared to wake him up.

This was crucial because Hitler was the person who could release the armored reserves.

And when he woke up, he still didn't believe it was a full invasion.

THE TANKS REMAIN A HUNDRED MILES INLAND.

AND THE ONLY OTHER MAN WHO CAN MAKE A DIFFERENCE IS EVEN FURTHER AWAY IN GERMANY, CELEBRATING HIS WIFE'S BIRTHDAY.

Rommel said the first 24 hours are crucial to defeat the Allied invasion.

On 6th June, he was not here.

It was only in late afternoon that Rommel rushed back from Germany and arrived in France to coordinate the defense measures.

But by that time, the Allies had already a firm grip on the beaches here.

AT 9:00AM, SEVEN HOURS AFTER THE FIRST SHOTS ARE FIRED, THE BUNKER NEXT TO GOCKEL'S POSITION IS DESTROYED.

HIS MACHINE GUN IS THE LAST ONE STILL FIRING FROM HIS GROUP OF BUNKERS.

[Gockel] 'Sand caused the belt of my machine gun to jam.

'I had to continue, using my rifle, firing single shots.'

AMAZINGLY THE GERMANS ARE HOLDING BACK THE AMERICANS.

BUT DESPITE THE MONTHS OF PREPARATION, THEY ARE RUNNING LOW ON AMMUNITION.

The German's were supposed to have ammunition for 48 hours on the Atlantic Wall.

In reality, they had in this section only ammunition for three and a half hours.

So at 10 o'clock, the Germans were starting to run out of ammunition.

AS THEIR SUPPLY OF BULLETS IS DEPLETED, THE GERMANS BEGIN TO STRUGGLE, AND THE AMERICANS GAIN GROUND.

GOCKEL AND HIS COMRADES ARE FORCED TO FALL BACK.

[Gockel] 'I was making my way up a slope.

'I crawled to the top to reach my comrades.'

[Gockel] 'I saw three fingers on my left hand 'dangling by the threads.'

NOW WOUNDED, GOCKEL RETREATS WITH THE FEW SURVIVORS OF HIS COMPANY.

OMAHA IS THE LAST OF FIVE INVASION BEACHES TO FALL.

THE 3,000-MILE ATLANTIC WALL HAS TAKEN THREE YEARS TO BUILD, BUT IS BREACHED IN A MATTER OF HOURS.

THE GERMANS LOST THE BATTLE AND SOON WILL LOSE THE WAR.

Despite all the cost, millions of Reichsmarks and millions of cubic meters of concrete built in to these structures, the Atlantic Wall could not hold the Allied invasion force.

The Atlantic Wall doesn't work for a number of reasons.

It stretched too far, there are too many gaps in it, the basic policy behind it is flawed.

The Germans never come up with a grand plan of how to fight this machine they've built, how they're going to take it into war.

DESPITE THE WALL'S FAILURE, XAVER DORSCH REMAINED HEAD OF THE TODT ORGANIZATION UNTIL GERMANY'S SURRENDER.

AFTER THE WAR, HE HAD A SUCCESSFUL ENGINEERING CAREER UNTIL HIS DEATH AGED 86.

ROMMEL WAS FORCED TO COMMIT SUICIDE BY HITLER JUST FOUR MONTHS AFTER D-DAY.

FRANZ GOCKEL SURVIVED THE WAR, RETURNING TO GERMANY WHERE HE MARRIED AND LIVED UNTIL THE AGE OF 80.

HE CAME BACK TO NORMANDY SEVERAL TIMES TO REMEMBER THE MEN WHO DIED FOR, AND AGAINST, THE WALL.

I think D-Day is probably the most important event in Europe to have occurred perhaps over the last 500 years, to kick Nazi Germany back into touch and to take back control for civilization.

I think it's an absolutely astounding event.

And it works because the Allies got their act together, and the Germans never did, it's as simple as that.

THE ALLIED INVASION OF NAZI-OCCUPIED EUROPE WAS AN ASTOUNDING SUCCESS.

BUT THE ALLIES SUFFERED 10,000 CASUALTIES IN NORMANDY, INCLUDING OVER 2,000 AMERICANS ON OMAHA BEACH ALONE.

NEXT TIME ON "NAZI MEGA WEAPONS"...

It's one of the biggest construction projects ever attempted anywhere in the world.

That's the thickness of three stories of solid concrete.

The U-Boat War was the only thing that frightened Churchill about the War.

The bunkers would've been the last safe haven they ever knew.

THIS IS THE STORY OF HITLER'S NAZI U-BOAT PENS.

[Announcer] "Nazi Mega Weapons" [Announcer] To learn more about this program or any of the other episodes in this series, visit us online at pbs.org/nazimegaweapons "Nazi Mega Weapons" is available on DVD.

To order, visit shopPBS.org or call 1-800-PLAY-PBS