Original subtitles

(dramatic music)

A ghostly hulk on a sandy grave

off the South American coast.

Yet this crumbling tomb was once a pride of the Nazi fleet,

a deadly weapon of war that sent scores

of sailors and ships to the bottom.

They were in fact one of the best submarines

in the German Navy.

She's armed with 15 torpedoes as well as a deck gun,

and she is absolutely deadly weapon of war.

In command, a legendary U-boat ace,

respected and admired on both sides.

Guggenberger was an excellent commanding officer

and leader of men.

He was in the finest tradition

of the German submarine commanders.

But the tide turned and the wolfpacks

were ruthlessly hunted down.

They call for battle station,

so all the guns are manned.

Every bomb can be a hit.

If someone says they weren't afraid, they're lying.

(shouting in foreign language)

(explosion booming)

The U-513 vanished,

but the U-995 is a rare survivor.

More than 600 of her type were unleashed to prowl the seas.

She's the only one left.

Captured in 1945, she now rests on a beach

below a memorial to the thousands of German sailors

who didn't come back.

It's interesting how the legend of the German Grey Wolves

endures to this day.

It's particularly interesting that people in the US

and Britain seemed to be more fascinated

by German submarines than they are

with the exploits of their own.

And I think we can only put it down really

to the fascination with the underdog,

with the defeated enemy, with the lost cause.

Brazilian sailor and entrepreneur

Vilfredo Schurmann is one of those

captivated by the legend.

When he heard the intriguing tale

of a U-boat sunk off the coast of his native Brazil,

he had to find it.

(speaking in foreign language)

The U-boat has an incredibly

engaging history.

It enthralled me immediately.

It was as if I was being pulled into this search.

Of course, not least because of my family.

My father is German.

I'm desperate to find out what this U-boat

meant for the war.

The Brazilian businessman was chasing a ghost,

a legend that vanished under the waves in 1943, a lone wolf.

The U-513.

People said, "Forget it, Vilfredo.

You will never find a thing.

Give up, you're dreaming."

I said, "No, we will find it."

(speaking in foreign language)

He wandered back through time

to the desperate early days of the war

when the so-called wolfpacks ruled the waves.

German U-boats tore into Atlantic convoys.

Vital supplies needed to keep Britain and her Allies afloat

were sent into the abyss,

along with many thousands of merchant seamen.

There's no doubt that early in the war

the Germans could have knocked Britain out using U-boats.

Even the mightiest warships

in the sheltered British naval base of Scapa Flow

weren't safe after a Grey Wolf crept in.

(dramatic music)

Probably one of the greatest successes scored

by the U-boat arm was Guenther Prien's penetration

of Scapa Flow in 1939.

This was striking at the Royal Navy

right in its lair, in its prime base,

and the propaganda's success of this was extraordinary.

It was a navigational masterpiece.

And on top of that,

there were barriers in front of the entrance

in this relatively small space.

Strong currents were also prevalent there.

(speaking in foreign language)

An American journalist described

Guenther Prien as clean cut and cocky.

He was also persistent.

He fired three torpedoes at the battleship Royal Oak.

All three failed.

At great risk he launched another attack.

(explosion booming)

British power was symbolized by its fleet, by sea power.

And here are young representatives of the Third Reich

proving that the old British Empire hasn't got the strength.

Royal Oak was an old ship.

She hadn't been modernized,

but to sink her in Britain's base,

the base of what was still seen as

the greatest Royal Navy in the world,

the greatest navy in the world,

was an extraordinary success.

(speaking in foreign language)

Prien became a celebrity,

paraded before the propaganda cameras.

(speaking in foreign language)

The Nazi propaganda machine went into overdrive

after Prien's success.

So he was interviewed by Hitler.

He was filmed.

He was awarded the Knight's Cross.

He was made into a young hero of the Third Reich.

Hitler was delighted.

His plans to conquer Europe and the Soviet Union

would be much easier with Britain out of the war.

U-boats could cut supply lines

and starve the island nation into submission.

Dönitz, the German commander of the German submarines,

argued this.

That if he had enough submarines,

he could sink 600,000 tons of shipping per month,

and this would knock Britain out of the war.

The Nazi Kriegsmarine started

with a fleet of 57 submarines.

More than 1100 U-boats would be launched into battle.

But as well as boats,

the German Navy needed sailors to man them.

A lot of young men would have looked at the U-boat arm

and seen them as glamorous, successful,

the spear point of the German Navy,

when the rest of the fleet was spending

an awful lot of time in port.

And also we must remember that young men everywhere

always think of themselves as invincible.

Horst Bredow was just 17 when he enlisted.

I desperately wanted to join the U-boat units

when I joined the Navy.

You were really put through the mill.

They checked you thoroughly.

You had to prove yourself.

(speaking in foreign language)

Recruits was sworn in

with the Admiral Dönitz mantra.

Attack, approach, sink it.

This was an elite which you would want to

connect yourself with.

And it's a sign, I think,

of the success of the propaganda machine,

the cult of the U-boat aces,

that it was so attractive for people to volunteer

for what turned out perhaps to be a rather nasty,

brutish, and short experience of operating submarines.

But life at sea wasn't always the worst option.

You could sit in a foxhole in the Russian front.

You could perhaps train up

as an ill-trained night fighter pilot,

or you could go to sea in submarines

where the risks on patrol were extraordinary,

but when you came back,

you were in France in relative safety,

in a barracks in relative comfort.

Sailors eager for adventure could travel

across the globe in a new generation

of long distance U-boats.

The U-513 was one of them.

The U-513 was a formidable weapon.

She is a Type IXC U-boat.

These are long range U-boats designed

for distant ocean patrolling.

Sometimes they're called U-cruisers.

So their endurance was something like

13 and a half thousand miles

instead of about eight and a half

for a standard Type VII sea boat.

She's armed with 15 torpedoes as well as a deck gun,

and she is a absolutely deadly weapon of war.

(speaking in foreign language)

Her crew claimed four kills in a month,

but then suffered a series of breakdowns

in mechanics and morale.

The commander was replaced by one of the most

dynamic officers in the fleet,

a 28-year-old who was already a legend.

Friedrich Guggenberger is an interesting character.

He's often portrayed as a maverick U-boat commander,

and in fact Admiral Dönitz used to reprimand him

for the length of his hair.

But he was successful.

He knew how to get results.

By reputation he handled his submarine

in a very aggressive kind of way.

He was in the finest tradition

of the German submarine commanders in that sense.

He'd already sent at least a dozen ships

to the bottom, including one stunning kill

that sunk a prize of Britain's Royal Navy.

Guggenberger's moment in the sun before this,

and the moment where he really becomes a U-boat ace

is when he torpedoes the British aircraft carrier

HMS Ark Royal.

The Germans have been going after Ark Royal

since the start of the war,

and have repeatedly claimed to have sunk her,

but Guggenberger is the man who actually gets her.

(speaking in foreign language)

(explosion booming)

It blasted another hole in British Naval pride.

(speaking in foreign language)

That was a real success

because it created a hole.

And in those days you didn't have this serial manufacturer

of aircraft carriers.

So every one of them was a serious loss for the enemy.

Guggenberger became another fated U-boat ace,

a hero of Nazi Germany.

(speaking in foreign language)

Ark Royal was a very important ship to both sides.

so it was natural that Guggenberger,

as the man who sank her,

should be given the highest possible gallantry award

with the maximum level of publicity.

The British were sad that Ark Royal had finally been sunk.

The Germans were overjoyed.

He was awarded one of the highest honors

by the Fuhrer himself.

The Knight's Cross with Oak Leaves.

In May 1943 he had a new boat and a new mission.

Loaded with torpedoes, enough food for 16 weeks,

and tropical uniforms, they were bound for exotic,

dangerous waters.

The deadly consequences of Japan's surprise attack

on Pearl Harbor in December 1941

had spread far beyond the Pacific.

Hitler declared war on America three days later.

Her vast industrial and military might

brought the wolfpacks to heel.

Once the US is in the war,

the Western Hemisphere basically becomes

just as dangerous as the mid-Atlantic

in the east for U-boats.

The entire might of the US Navy, the US Coast Guard,

plus their Allies eventually like the Brazilians

becomes arranged against the German submarines.

America could build merchant ships

faster than the Germans could sink them.

As well as tanks and planes,

factories churned out a stream of so-called Liberty ships.

The key to the mass production of merchant ships

was to come up with a simple common design

which could be welded together quite rapidly.

The tonnage lost could be replaced,

and indeed the size of the Allied merchant fleet increased.

No matter how many ships the U-boats sunk,

there were two or three more to take their place.

But fear of the Grey Wolves remained,

and for good reason.

Long range U-boats were still prowling far and wide.

In September 1942, the troop ship Laconia

set sail from Cape Town for Liverpool.

Civilians on board included 14-year-old Josephine Pratchett

and her family.

At that time, the Atlantic U-boat war was at its height.

There were huge, tremendous successes for the U-boats.

Our ship was very slow,

belching out black smoke the whole time.

And we knew we had to go through the Atlantic

where they all were.

Unfortunately for the Laconia,

the U-156 was lurking off the West African coast.

The passenger ship Laconia was armed

and operating as a troop ship,

so she was absolutely a valid target.

Lieutenant Commander Werner Hartenstein

sees the opportunity to send another Allied ship

to the bottom.

It was horrendous.

The ship lurched very badly.

The explosion was extremely loud.

And then there was a kind of

incredulity, really.

You know, a hush

before the next torpedo struck.

Many survivors were floundering in the water,

including Italian prisoners,

Lieutenant Commander Werner Hartenstein's allies.

Then he realized there were

Italians on board.

There were prisoners on board,

and his conscience was now stronger than any rules of war.

At great risk to himself and his men,

Hartenstein surfaced and called other U-boats to help.

His periscope came towards us, the submarine surfaced,

and the captain came onto the deck,

and with a megaphone he said in perfect English,

"I would like all the women and children

to come aboard my ship."

Can you imagine the enemy saying that?

We must also remember that what motivated him

was the fact that he heard the voices

of Italian prisoners of war in the water, his allies.

Whether he would have gone to the rescue

of Allied survivors alone, who knows.

But there's no doubt he did try and help everybody

who was in the water.

In times of war when you think what could have happened,

so you expect you could be rescued by your own side,

but you don't expect to be rescued by the other side,

do you really?

But we were.

And not only that, but we were treated extremely well,

and I've lived to tell the tale.

Some survivors were taken onboard the U-boats.

Others were towed in lifeboats behind them.

It was one of the most elaborate

rescue operations of the war.

The lifeboats were being towed by the submarines.

And he tried very hard to save

as many survivors as possible,

making himself extremely vulnerable.

Hartenstein made an open radio call in English,

assuring any ships that helped would not be attacked.

It attracted deadly attention.

It was an enemy submarine.

He has a chance to sink it, try and sink it.

Shoot first and ask questions afterwards.

It's a ruthless decision,

but they've got a chance to get a U-boat on the surface

at a point where the U-boat war is the single biggest threat

that the Allies are facing.

He said, "It's too dangerous.

I can't keep you on board anymore."

Survivors were cut loose.

Many were rescued by French ships.

The U-156 escaped and received a stern general order

from headquarters.

One of the interesting consequences

of the Hartenstein incident is that during its issues,

the Laconian order, forbidding U-boat commanders

from helping survivors.

In reality, it doesn't make any difference.

Conditions for U-boat commanders are getting

very, very difficult at this point,

and it's not long before no commander can afford

the luxury of indulging in this kind of behavior,

regardless of whether they get the opportunity or not.

Like her sister boat involved

in the Laconia incident,

the U-513 was a long range weapon.

She left her French base in Lorient

on the 18th of May 1943.

Her skipper, Friedrich Guggenberger,

could have picked a safer option as an instructor.

The German Navy would try to use the expertise

of somebody like Guggenberger.

And so there was good reason to use people

like him in the training mode.

But of course, these submarine commanders are aggressive.

It's in their bones,

and therefore he wanted to be sent out on patrol again.

For most of her crew,

it was the fourth assignment at sea.

Torpedo mechanic Gunther Bleise was just a teenager,

obliged to serve his Fuhrer.

I was 14 and my husband was 17 at the time,

and our childhood romance grew.

But then he had to become a soldier

before he'd even turned 18.

His engineering skills were in demand.

Most young men who left on a U-boat never came back,

but Margarethe would wait for her sweetheart.

I knew he was the one when I was 13.

And he was.

(speaking in foreign language)

It was a journey into the unknown.

For operational security reasons,

U-boat crews weren't told where they were going

until they'd left harbor.

Obviously what you don't want is the boys out for a night

on the town, in the bars of Lorient,

spouting to the locals about where they're going

the next day.

Walter Wittig was a radio operator

on a sister ship of U-513.

Of course you would think what was ahead

when you left on assignment.

Where are we going?

If someone says they weren't afraid, they're lying.

(speaking in foreign language)

Once out at sea,

the orders finally came through.

The U-513 faced a long voyage far beyond the relative safety

of her home base on the French coast.

(dramatic music)

(speaking in foreign language)

She set a course for the other side of the Atlantic,

for the waters south of Rio de Janeiro.

(dramatic music)

It was a rich hunting ground for freighters

carrying a vital raw material for the Allied war effort.

Brazil is essentially the only large-scale source

of rubber remaining to the Allies.

The Germans ally, the Japanese,

has captured nearly all the other major

rubber producing areas: Indonesia, Malaysia, and so on.

So Brazilian rubber becomes this vital resource

for the Allied war effort.

And the Germans know this.

It's a long, long way away,

but they're still able to dispatch

these long range Type IX U-boats.

On the long, uneventful voyage,

the commander had to ensure his crew was ship-shape.

It gave them the best possible chance

of making it back home to their loved ones.

(singing in foreign language)

He's well aware that he's got perhaps

a less than a 100% efficient crew.

He drills them and trains them relentlessly

as they cross the Atlantic.

(yelling in foreign language)

The big Type IXCs, these were very large U-boats,

and they were known as slow divers.

(speaking in foreign language)

Guggenberger made sure that he ran,

we say in English, a tight ship,

that the training of every member of the crew

was absolutely vital to the efficiency of the submarine.

And that to a very considerable extent

the crew would have to be driven to make sure

that they were operating at maximum efficiency.

(speaking in foreign language)

And with an acknowledged ace in command,

I suspect that the men,

although they might grumble about it,

probably felt confident in the end that they were in fact

in one of the best submarines in the German Navy.

In fact, their boat changed from being one of the worst

to being one of the most potentially

effective submarines in the Kriegsmarine.

In a real attack,

a U-boat on the surface was a sitting duck.

The commander presses the alarm signal,

and that means an emergency dive.

Nobody knows if this is an exercise or the real thing.

It took 35 seconds for a Type IXC to crash dive

and get underwater.

And it was absolutely essential that they shaved

every second that they could after that time.

(watch clicking)

(speaking in foreign language)

U-boats had to maintain a constant watch.

Smoke on the horizon meant a possible target

or an attacker closing in,

but a long voyage to Brazil was mostly uneventful,

hot, stinking and claustrophobic.

We always said that the engineers

designed a fantastic boat with fantastic technology,

but when they finished they realized,

dear god, people have to go in there, too.

A chance to escape the cramped confines

came when the horizon was clear and the water calm,

the open sea a welcome reprieve from a steamy interior

on a tropical voyage.

(upbeat music)

It was a mixture of sweat,

torpedo fumes, chlorine fumes from the battery,

also the smell of the galley.

Now imagine all this together in one room.

Eventually you no longer perceive it,

but the circumstances under which the crew

had to live in the U-boats are hard to imagine.

(speaking in foreign language)

Apart from the occasional rendezvous

with supply vessels, including modified U-boats

dubbed milk cows, crews were on their own.

(dramatic music)

Their lives depended on the seaworthiness of their boat,

and there was a vast array of machinery to maintain.

The all-important batteries needed constant topping up

with fresh water.

U-513 chief engineer Gunter Seidel was fanatical

about preserving water.

One of the major problems submarines face

right from the start was their very limited capacity

to carry fresh water.

And this had effects on submariners' way of life.

Washing and operating conventional submarines

don't go together.

Even today, in fact,

conservation of water is very important.

But when the miserly Seidel banned coffee,

the commander stepped in.

Guggenberger was an excellent commanding officer

and leader of men, but he also has an absolutely,

finely nuanced eye for reading his men's moods.

(speaking in foreign language)

A good example of that is the story of

his chief engineer banning coffee to preserve water,

and one has some sympathy for him.

Water's a vital resource,

but Guggenberger reads the mood and goes, no,

the men are having their coffee

and immediately gets them onside.

(speaking in foreign language)

Comradery was an important thing on board.

Of course, there was a difference between superiors

and subordinates, but not in the same way as it was

on a big ship or on land.

That didn't exist on a U-boat.

It was a tight-knit community.

(speaking in foreign language)

Crammed together in small steel tube

thousands of miles from home,

events like birthdays broke the monotony

of endless days at sea.

(singing in foreign language)

It's not possible to teach someone

who's been blind from birth about color.

And if you haven't lived through it,

this state of being completely reliant on each other,

it's difficult to understand

what this companionship actually meant.

(speaking in foreign language)

Submariners could spend weeks at sea

without seeing another boat,

yet their orders were clear.

Sink ships.

(dramatic music)

You travel back and forth,

hoping you will come across someone, anyone.

(speaking in foreign language)

After two months at sea,

(yelling in foreign language)

the lookouts spotted a target on the 21st of June.

(yelling in foreign language)

Sinking a enemy ship with a torpedo from a submarine

is a really tricky business.

(speaking in foreign language)

It's a scientific mathematical game.

(speaking in foreign language)

What the commanding officer has to do is look at his target

and he has to judge where it's gonna be

when his torpedo reaches it.

So he's looking at the speed and course of the target.

(speaking in foreign language)

He's looking at the speed and direction

of travel of his torpedo.

And if he gets it right, they'll meet on the cross.

(speaking in foreign language)

What a submarine captain can't do is stay on the surface

with his periscope and look at what's happening.

It's far too dangerous.

(speaking in foreign language)

So what he does is he will fire his torpedo

to his calculations, fire his torpedo.

(speaking in foreign language)

(watch ticking)

And then the eels go off

and we sit and we wait.

Eyes on the stopwatch to see how much longer

they should travel, and wait for the bang.

The stopwatch is his running time for that torpedo.

When it reaches, say 50 seconds or two minutes

or four minutes, he should hear the thump.

(explosion booming)

(explosion thumping)

(speaking in foreign language)

(crew cheering)

The Swedish freighter Venezia was sunk.

The crew saved themselves, but this wasn't always the case.

When they managed to one, they all cheered.

The crew was elated.

It's understandable.

This was their job.

For most U-boat crews,

such elation was short-lived.

Allied ships and planes worked together to protect convoys,

and to hunt and destroy boats like the U-513.

By '43, you are facing a mature anti-submarine system.

There are some ships that are in convoy.

Other ships are not.

But the Americans have developed a very effective

hunter-killer system for dealing with submarines.

And as Guggenberger found off the Brazilian coast

in the summer of 1943,

it was almost as bad as being in mid-Atlantic.

Bad weather was no cover.

The hunter-killers could still find a U-boat in a storm.

The most important thing was to get as deep as possible

as fast as possible.

(speaking in foreign language)

On the surface, a U-boat is just a very thin-skinned,

slow, and very vulnerable metal boat.

(speaking in foreign language)

Silence on a submerged submarine is vital

if you're not gonna be found.

(speaking in foreign language)

Ping is active sonar.

Passive sonar is a guy with headphones

and effectively ears on the side of his ship,

and they can hear the slightest noise.

You can only be really quiet.

Don't run about.

All machines are off.

But other than that, you can do virtually nothing.

That's the guy who would hear you drop

your pen on the deck.

Once you've done that,

the searching warship knows that there's a submarine there.

(speaking in foreign language)

Then they can start pinging with their active sonar.

(sonar pinging)

That's when they learn to pray.

And find you and find how deep you are,

and find how far away you are,

and then you're essentially dead.

(yelling in foreign language)

(explosion booming)

(speaking in foreign language)

Every bomb can be a hit.

What's important is that the bombs explode

above the boat and not below the boat.

If they explode below, it's usually all over.

(speaking in foreign language)

You can't really describe it.

Once we had a situation where it went on

from eight in the morning until 10 at night.

(speaking in foreign language)

And then you have three ships up there

and they cross over and take turns discharging bombs.

The stress of being repeatedly depth charged

and hunted down for hours and hours and hours at a time

is again almost inconceivable for us today.

The psychological reflex is to fight or flee,

and the submariner can't do that.

He just to sit there and take it.

That's when you try not to

think about anything.

(speaking in foreign language)

American planes sunk at least 16 U-boats

in the South Atlantic in 1943 and '44.

At the beginning of July 1943,

the U-513 had survived to kill another day.

Once a target was spotted, the crew tried to

identify it using a shipping register.

(speaking in foreign language)

(dramatic music)

(speaking in foreign language)

The U-513 scored five impressive kills

off the Brazilian coast,

including two American-built Liberty freighters.

Guggenberger manages to seek five ships

off the coast of Brazil in summer of 1943.

This is not a good time for U-boats.

The U-boat campaign is on the way in here.

The U-boat army is being defeated,

and it speaks volumes for his qualities

as a commanding officer that he manages

to achieve that kind of success rate

in a very difficult period for submarine commanders.

(dramatic music)

But success seems to have sparked

a rare moment of carelessness by the veteran U-boat ace.

(speaking in foreign language)

The U-513 sent a radio report back to headquarters.

(speaking in foreign language)

At the start of the war that was normal,

but other than that we hardly ever sent long radio messages.

(speaking in foreign language)

I only ever sent a single message

from the Brazilian coastline,

and that was a signal with seven letters.

(speaking in foreign language)

Even a short message could reveal

a U-boat's position.

You need two receivers, both of which will intercept

the same wireless transmission.

What you get then is a cross bearing.

And if you run down the bearings where they cross,

that's exactly where the U-boat is,

and then you can dispatch escort forces

and hunter-killer groups to go find the submarine

and sink it.

Basically what he was saying in code was,

here I am, come and kill me.

American mariner sea planes

were a lethal threat,

able to zero in on any U-boat caught on the surface.

The Americans had a very effective

radio direction finding system for, as we say,

queuing flying boats to go out and search in areas.

This is a great, big, lumbering flying boat

bristling with weaponry, capable of flying thousands

of miles out across the ocean and back again.

And when this aircraft encounters U-513 on the surface,

the odds are heavily in favor of the pilot.

I decided to turn on the radar

and flipped it on and started watching it awhile.

And then I saw this very peculiar breadth

which was very sharp and very distinct.

I thought it was a fishing boat at first.

Has a little curve to it, but it was so bright.

It just, just jumped out at you.

It didn't seem quite right for a wooden vessel.

(dramatic music)

And one of the bombardier, he got binoculars,

and he says it's a submarine.

And then Roy, Roy started working his way

into the clouds so that he would be better concealed.

Guggenberger is caught napping

by the mariner patrol aircraft.

There are several options he could have done.

He could have immediately ordered his crew below

and crash dived as soon as possible.

Guns to extension!

But it's still gonna take 35 seconds,

which would have seemed agonizingly long.

(gun firing)

Basically he's lost the battle, really,

when the aircraft catches him unawares.

They call for battle station,

so all the guns are manned.

According to one account,

the deck gun jammed.

But whatever firepower was available,

it was no match for the mariner.

The greatest terror for any U-boat commander in 1943

is to be caught on the surface by an aircraft.

An aircraft is a almost guaranteed U-boat killer.

And certainly what submarines don't have

is a chance of fighting out the battle against an airplane.

The mariner dropped depth charges

around the U-513.

A killer blow exploded just below the boat.

Torpedo mechanic Gunther Bleise was one of the lucky few

saved by a shipmate.

He had seen the aircraft and called down,

"Gunther, come up here!"

We'll never know if it was intuition.

If that hadn't happened, he would have sunk

with the rest of them.

(speaking in foreign language)

For most of those on board,

the boat became their tomb.

66 years later, the search for the U-513 started

with a former American airman who played a key role

in sinking it.

Hello, Mr. Stotts.

Nice to meet you.

Determined to find the enigmatic wreck

off his native Brazil,

businessman Vilfredo Schurmann was hunting for clues.

The U-513 kill daubed on the plane that sent her

to the bottom.

The former airman had the approximate coordinates

of where his crew had sunk her.

I don't really know.

You could, you could take in there they give the position

that the Navy thinks it was.

And you can figure that out.

How far off shore we were.

That's all there is right there.

The coordinates were not precise.

From Texas, the quest to find the U-513 continued

from the Brazilian port of Florianopolis, south of Rio.

Local fishermen provided more clues.

The locations of mysterious obstacles on the sea floor

that tore their nets.

It's cold, but inside I'm feeling

hot with excitement.

Another intriguing voyage began

to the scene of a fateful battle

a hundred kilometers off shore.

The crew deployed a side scan sonar,

a radar device they hoped would reveal the lost wreck.

But after 17 trips and days of searching,

the enigmatic U-boat eluded them

until a strange signal emerged

some 75 meters below the boat.

(speaking in foreign language)

(crew cheering)

An elated crew were sure they'd found the U-513,

but the object was too deep for divers to investigate.

(speaking in foreign language)

A remote controlled camera was sent down to

illuminate what lay in the eerie darkness below.

(speaking in foreign language)

Divers checked that the video link to the ship was working

before the camera was directed to the sea floor.

There were anxious moments as another apparently

featureless sandy vista stretched before them,

until a ghostly shape emerged in the gloom.

After almost 70 years after she vanished,

the Grey Wolf U-513 was found.

(crew cheering)

(dramatic music)

A wreck, and also a grave for 46 sailors.

(dramatic music)

A torn hull, evidence of the depth charge blast

that sent them to their doom.

(speaking in foreign language)

(dramatic music)

But a lucky few escaped in the critical seconds

before she sank.

After the attack, there were about

five or six men in the water.

So

we circled low and dropped two life rafts.

Among the survivors,

the captain and legendary U-boat ace Friedrich Guggenberger.

Guggenberger obviously chooses not to go

down with his ship.

To be honest, this whole issue of of a captain

going down with his ship is sentimental rubbish.

A captain's duty on either side is to get back,

get back in the war and bring back the lessons

that he's learned from the battle that he's taken part in.

And you'll find that on both sides

during the Second World War,

most commanding officers will try and keep themselves

and their men alive.

Even when scrambling for their lives,

crewmen continued to respect their skipper.

(speaking in foreign language)

He'd taken off his clothes in the water

and was only wearing his thick jumper.

And then he asked his captain,

"Captain, may I request to enter the boat?

I'm only wearing a jumper."

He didn't really want to get in half-naked.

He was always considering etiquette.

(speaking in foreign language)

Seven survivors made it onto the life rafts

before they were picked up by the American Navy.

It would be standard operating procedure

the call in a surface ship, just to see what had happened,

and also to pick up survivors.

After all, picking up a U-boat captain might yield

a certain amount of intelligence, for example.

So there wasn't just humanitarian interest

in trying to pick up the crew.

Even though his U-boat was at the bottom

of the South Atlantic, Capitan Lieutenant Guggenberger

continued the fight in captivity.

With officers like Guggenberger,

trying to keep them in was often difficult.

And of course, Guggenberger's involved

in one of the great escapes on the, on the American side.

One of the best illustrations of this point

that Guggenberger's duty was to keep in the war

is really the fact that even as a prisoner

in the United States, he escapes from captivity twice.

First time heading for Mexico.

He hasn't really got much of a chance of getting home,

although Mexico is neutral.

But what he has got a chance of being

is a monumental pain in the neck to his captors,

forcing them to deploy troops, frightening civilians,

getting a propaganda success.

So he's doing everything he can to stay in the fight

even as a prisoner in the US.

Together with 24 others,

he staged his own great escape,

tunneling out around Christmas 1944.

But in the United States,

you would stick out like a sore thumb

as somebody who spoke English with a strong accent,

particularly in a state like Arizona.

They were recaptured within weeks.

(dramatic music)

There was also no escape for their comrades

still fighting a losing war on the high seas.

Three in four U-boats never made it home.

The survivors of the U-513 were released in 1946.

Torpedo mechanic Gunther Bleise married

his childhood sweetheart Margarethe,

who ensured his compelling tale of service and survival

was recorded for this program.

As for his acclaimed captain Friederich Guggenberger,

the exploits and adventures continued long after the war.

The thing with most of the U-boat aces

is they had a tendency to live fast and die young.

Guggenberger survives the war,

and his career continues.

At the end of the war the German Navy is disbanded.

There is no German Navy.

So this incredibly intelligent, motivated young guy

trains as an architect.

When Germany gets a Navy back in the 1950s, he re-enlists.

He becomes a senior admiral with a senior position in NATO,

and retires, you know, with the plaudits and honors

of not just his nation, but his former enemies.

And then he dies this bizarre, mysterious death

at home as an elderly man.

Goes for a walk in the forest, never comes back,

and his body's found two years later in the woods.

It's all part of the intriguing story

that compelled another sailor to find

Guggenberger's last command:

the long lost wreck of the U-513.

(speaking in foreign language)

Really, it is an incredible feeling

that we found this U-boat.

We can hardly believe it.

I am just ecstatic to be part of its incredible story.

It's a story of bravery, desperation,

and sacrifice on both sides.

The Naval Memorial to German war dead,

including more than 30,000 submariners survives,

not to glorify war,

but to pay tribute to the sailors

who made the ultimate sacrifice for their country.

(dramatic music)