All language subtitles for World War II Secrets From Above - Season 2 - EP-02 - Battle Of The Atlantic

The 3rd of September 1939, a
British passenger ship, the SS Athenia,

steams across the Atlantic
Ocean, bound for Canada.

Back home, Britain has just
declared war on Nazi Germany.

Now a predator hunts the
Athenia beneath the waves,

a Nazi U-boat submarine.

At 7.40pm, a torpedo slams
into the liner and sinks it.

117 people on board lose their lives.

These are the first shots
fired in the Battle of the Atlantic,

a ruthless six-year
campaign to bring Britain

to its knees and force
its people to surrender.

In this series, we investigate
the most extraordinary events

of World War II from a brand-new perspective,
matching rarely-seen archive film...

..photography from the front line...

..and declassified aerial reconnaissance
images... ..to their original locations.

We reconstruct the crucial
battles... ..daring bombing raids...

..and deadly terror weapons,
which change the course of history.

Soaring over the battlefields, we reveal
the secrets of World War II from above.

In 1939, a German reconnaissance aircraft

crosses the English Channel.

Its target is the city of Portsmouth
on England's south coast.

As the Nazi pilot soars over its dockyards,

the on-board camera
reveals a remarkable sight.

Below, ships of the Royal Navy.

This is the most powerful
fleet on the planet.

At the start of the Second World War,

the battle for the oceans
looks like a one-sided contest.

On paper, Britain has the largest
navy and the biggest empire in the world.

The British have more than 400 vessels.

That's more than four times as
many ships as the German fleet.

But as an island nation, the
United Kingdom is also vulnerable.

It relies heavily on imported goods,

most of which come from
across the Atlantic Ocean.

Merchant ships bring
in a million tonnes of

critical fuel and food
supplies every year.

Wheat from Canada,
oil from the United States,

and fruit and sugar
from the Caribbean.

Germany knows that if it can
attack these shipping routes

and sever Britain's lifeline,
the war in Europe will be over...

..before it has barely begun.

A clue to how the Nazis plan
to win the Battle of the Atlantic

lies here in the city of Kiel.

In the 1930s, Kiel is the headquarters
of the German navy, the Kriegsmarine,

and where the Nazis embark on a
vast naval rearmament programme.

This aerial photograph reveals
how Kiel's immense dockyards

churn out huge new battleships.

These Nazi combat vessels are
the most advanced in the world.

They are designed specifically
to hunt down and destroy

British merchant ships.

The Nazi dictator Adolf Hitler revels
in the prestige of these new warships.

But in 1939, Germany's admirals
know it will be another five years

until their fleet can
challenge Britain's Royal Navy.

The British Home Fleet patrols the North
Sea from their base at Scapa Flow in Orkney.

Their aim is to prevent the German
navy from reaching the Atlantic Ocean.

So to even the odds,
the Nazis turn to a relic of

the First World War - the
legendary U-boat submarine.

Naval historian Jan Witt explores U-995

that now lies on the icy
shoreline of the Baltic Sea.

The U-boats became almost a matter of myth

because on the German
side, they were presented by

the propaganda as the
grey wolves of the Atlantic.

The invincible U-boats that had
so many successes in sinking ships.

The U-boat is the ultimate
underwater stealth weapon.

With two supercharged engines
running on 114 tonnes of diesel...

..this submarine can cover over 18,000km,
enough to reach New York and back.

U-995 can carry 14 deadly torpedoes.

In battle, it can fire one from
its tail and four from its nose.

At 50km/h, these subaquatic missiles
swim faster than any merchant ship.

Jan investigates U-995's cramped interior

to discover how everything about
this submarine is purpose-built for war.

I'm standing now in the bow torpedo room,

which was also the living
quarter for the main crew.

You press in everything you
need for a U-boat to function -

engines, controls, weaponry - and the
little space that is left is for the crew.

The 27 men on board this submarine could
stay submerged for up to 72 hours at a time,

waiting for the moment to strike.

A U-boat could appear out
of nowhere, sink ships in the

blink of an eye and vanish
as quickly as it had appeared.

Fortunately for the British, the Nazis had
fewer than 50 operational U-boats in 1939.

Many in the German navy still
see battleships as the key to victory.

But an ambitious naval
officer, Admiral Karl Dönitz,

has a secret plan to boost U-boat
production on a massive scale.

He's the head of
Germany's submarine service

and believes that with 300 U-boats,

he can single-handedly win the war.

Dönitz devises a daring
raid to prove his point.

He plans to attack the
Royal Navy on home turf,

here at Scapa Flow in Orkney,
off the coast of Scotland.

Emily Turton is an
expert diver and skipper.

She investigates how Dönitz plans
to pull off this near-suicidal mission.

The British naval base at Scapa
Flow is supposed to be impregnable.

So Scapa Flow is a natural harbour.

It's strategically really
well placed for us

to be in both the Atlantic
and the North Sea.

So easy to protect in that
we have narrow entrances

into this big bit of water where
we can house an entire fleet.

The British have fortified
Scapa Flow's natural geography.

They have sunk derelict
vessels called block ships

at strategic locations to
control the ways in and out.

But a German scouting mission
reveals that the block ships

in one of the narrow channels
have not been maintained.

Dönitz thinks there is a wide enough gap
between them for a U-boat to sneak through.

On the night of 13 October 1939,

he seizes the opportunity to strike.

Under a new moon, U-47 approaches
Scapa Flow and heads for Kirk Sound.

Once inside, it spots a warship,
HMS Royal Oak, at anchor.

It's a sitting duck.

Just before 1am, the U-boat fires three
torpedoes at the unsuspecting battleship.

One torpedo hits the vessel,
causing only minor damage.

The Germans reload and fire again.

This time, they blow two
holes in the stricken vessel.

As HMS Royal Oak rolls over and capsizes,
U-47 slips away in the dead of night.

Today, this buoy marks the spot

where 835 British sailors
lose their lives in the raid.

The German navy has shown it is
capable of bringing war home to Britain.

- The actual sinking of the Royal
Oak would have been quite brutal.

There would have
been a lot of flash and

blasts caused by the
torpedoes inside the ship.

So it's a huge blow to morale for a U-boat

to successfully navigate
their way into Scapa Flow,

and yes, under the cover
of darkness, but still, to get

into Scapa Flow and then
manage to sink a capital warship.

It's a massive disaster at
the beginning of World War II.

- The Royal Navy upgrades Scapa
Flow's defences after the attack.

Engineers build huge new causeways

called Churchill Barriers
to protect anchored ships.

They lay six miles of
anti-torpedo nets across

the water to prevent
future submarine attacks.

After the raid at Scapa Flow, U-47
returns home to a hero's welcome.

Its captain, Gunther Prien, receives
Germany's highest military decoration,

the Knight's Cross of the
Iron Cross with Oak Leaves.

At Kiel, the German Navy
ramps up submarine production.

From this moment on, the Battle of the
Atlantic will be a war against the U-boats.

Britain must find a way to defeat
these silent hunters before it is too late.

In the first month of
World War II, Nazi U-boats

sink 30 merchant ships
alone in the Atlantic Ocean.

Among them is the SS
Kensington Court, torpedoed on the

18th of September, 1939, while
carrying a shipment of grain.

Many of the cargo vessels that do
survive the perilous Atlantic voyage

unload their critical supplies here
in the northern city of Liverpool.

In 1939, this port on the banks of the River
Mersey is one of the busiest in the UK.

World War II expert Lauren Shacklady
investigates how Liverpool now plays a key role

in fighting the U-boats
and keeping Britain alive.

- All of this view that we have now

would have been completely
different during the war.

At the start of the war, we
only had a few weeks worth

of supplies in the country
at any one given time.

There would have been tons of ships
coming into the city every day, every week.

- The Admiralty knows
that it must protect its ships

heading for ports like
Liverpool, so it reactivates an

old World War I countermeasure
called the convoy system.

A convoy is a group of 30 to 40
merchant ships that sail together.

The vessels are spaced
up to one kilometer apart.

Warships from the
Royal Navy surround the

cargo vessels as they
travel across the ocean.

Most convoys sail from North America,

bringing vital war supplies
to ports like Liverpool.

Ships heading the
other way are less critical.

Some are only escorted for a few days.

The Royal Navy controls the entire
operation from its naval base in Plymouth.

The convoy system
can't protect every vessel.

In the first seven months of the
war, Germany sinks a staggering

222 merchant ships, but it
loses 18 U boats in return.

The tiny German Navy
can't sustain these losses.

By April 1940, the Kriegsmarine
has only 31 operational

submarines left until the
German army comes to its rescue.

In May 1940, Hitler's Blitzkrieg
knocks France out of the war.

At Dunkirk, the Germans force the
British to retreat back across the Channel.

Nazi troops now occupy all of France.

The French ports they now
control give the Nazis direct

access to the Atlantic
Ocean for the very first time.

With the fall of France quite early on in
the war, not only did Germany gain access

to all of the ports along
the French Atlantic coast,

they also mined the
English Channel with U-boats

and basically blockaded all
of our supply lines down there.

The Admiralty realizes that
its HQ in Plymouth is vulnerable

so it moves command of the entire
convoy system north to Liverpool.

They set up a top secret base

deep beneath this seemingly
ordinary office block.

Naval personnel build a huge
map room to track every convoy

crossing the Atlantic and alert
them to any U-boat sightings.

The Royal Navy hopes that the team in
Liverpool will keep the supplies flowing.

Unfortunately for them,
the Nazis set up a rival

operation at their bases
in occupied France.

Germany's Admiral Dönitz is a
former World War I U-boat commander.

He has spent years plotting how to defeat

the hated British convoys and
comes up with a new strategy.

Instead of a single U-boat
searching for a lone convoy,

Dönitz orders his U-boats to hunt together
in packs to coordinate their attacks.

The U-boats sail into the Atlantic
side by side, 16 kilometers apart.

The group stretches north to south like an
invisible net, cast out to snare a convoy.

When one submarine
spots the target, it doesn't

attack immediately, but
radios the others to join it.

All the U-boats then converge
on their prey like a pack of wolves.

The Atlantic Ocean now turns
into a gigantic chessboard,

one where thousands of lives are at stake.

Inside Liverpool's command
centre, naval personnel work

day and night trying to
guide the convoys to safety.

Eight out of 10 are women, with
so many young men away at sea.

- The people in here knew
that they had loved ones,

family members, partners
who were out on the ocean

and they're seeing all of
these ships sinking in real time.

It must have been a really
difficult job to do in that sense.

- The Allies try different
ruses to outwit the wolf packs.

They order their convoys
to change course frequently,

but Germany's new tactics
are a stunning success.

In 1940, the U-boats
sink 471 merchant ships,

most of them off the west
coast of the British Isles.

And the following year, another
432, largely along the convoy routes.

As Allied losses mount, U-boat
commanders call this the happy time.

By mid-1942, the U-boats
appear to have free reign

over the Atlantic, striking down more
than 1,000 ships, some as far as Mexico.

Britain seems powerless
to stop Hitler's U-boats,

but British Prime Minister Winston
Churchill is determined to strike back.

He plans a daring raid on the
German Navy deep in occupied France.

By January 1942, the war at
sea is firmly in Germany's favor.

Hitler's U-boat fleet has
grown to nearly 200 vessels.

Many of them sail south to ports
like San Nazaire in occupied France,

where the Nazis now
tighten their grip on power.

In March 1942, an Allied reconnaissance
plane takes this photograph of San Nazaire.

It reveals how the Nazis totally
transform this once peaceful port.

The Germans build a gigantic concrete bunker
called a U-boat pen in just 16 months.

Structural engineer Zeynab
Adegan investigates its secrets.

The San Nazaire base is
a huge engineering project.

Just the sheer magnitude
of people you would need

to be able to construct
such a large structure

in the space of time that they
had is absolutely mind-blowing.

To protect their submarine
base from bomb raids,

the Nazis build an
eight-metre-thick concrete roof.

Up to 20 U-boats can shelter here,
along with hundreds of crewmen.

They defend this concrete
megastructure with anti-aircraft guns.

This submarine fortress is the perfect
safe haven for a U-boat wolf pack.

Inside, Zeynab finds clues which reveal

how the Germans build
this enormous structure.

It's massive, isn't it?

It's almost intimidating, actually.

It's like a tiny little speck.

And just imagine, this
was only one of the rooms.

These faint lines on the wall
are the imprints of wooden panels.

They reveal that German
engineers build the bunker

by pouring the concrete layer
by layer into a wooden framework.

The construction technique used
is actually very similar to baking,

where you've got your mould
around it, which is the formwork.

Once the concrete is dry, you
take away the wooden panels

and you're left with a
really, really thick wall.

Saint Nazaire is one of five enormous
U-boat bases on the Atlantic coast.

But the Allies fear the Nazis
have even bigger plans for it.

The port's massive dry dock
is the only one big enough

on the Atlantic coast to house
Germany's new super battleship.

The Tirpitz.

In 1942, this giant is the most
powerful warship in the world.

The vessel is currently
moored in occupied Norway.

But the Allies are terrified that if
the Tirpitz reaches Saint Nazaire,

it will wreak more damage to the
convoys than an entire wolfpack of U-boats.

So they plan a daring commando raid to
put Saint Nazaire's dry dock out of action.

In the early hours of March 28th,

a small flotilla of Allied
ships heads for Saint Nazaire.

Among them is an old destroyer, HMS
Campbelltown, disguised as a German vessel.

Campbelltown's mission is to
ram the dry dock doors.

The Germans rain down heavy fire onto the
ship once they realise what's happening.

Against all odds, the Campbelltown
stays on course.

and at 1:34am smashes into the
dry dock gate at 35km/h.

British commandos now leap
out of the ship and wreak havoc.

They inflict even further
damage on the dockyard.

Over half of the commandos
are captured or killed.

But the dock is severely damaged.

The next day, the Germans
inspect the wreck of

the Campbelltown to
figure out how to remove it.

What they don't realise is that
the ship is a ticking time bomb.

Hidden below deck, commandos have rigged
over four tonnes of explosives to a timer.

At 10:30am, they detonate, sinking the
ship and making it impossible to tow away.

The raid is a spectacular success and
a huge psychological boost to the Allies.

The Tirpitz now has no
base on the Atlantic coast.

It never reaches the Allied convoys.

But the submarine pens remain undamaged.

The dwarf packs are still
free to hunt the convoys.

The Allies desperately need
a way to defeat the U-boats.

The solution lies not out at sea,

but right on their doorstep in a
quiet corner of southern England.

In 1938, the UK's Secret
Intelligence Service

takes control of a large house deep in
the English countryside - Bletchley Park.

Historian Tom Cheetham investigates
how this seemingly ordinary building

plays a game-changing role
in the Battle of the Atlantic.

It doesn't look like an
ideal wartime secret base

but this mansion
and the grounds around it,

they proved to be a suitable
nucleus for an organisation

which would grow many
times over during the war

and play an invaluable
role in Allied victory.

The German wolfpack
strategy relies on communication

between U-boats to
coordinate their deadly attacks.

From 1939, Bletchley becomes home
to hundreds of intelligence personnel.

They are all working towards a single goal
- cracking top-secret Nazi communications.

The German navy possesses
what it confidently believes

is an unbreakable code...

..thanks to an innovative device that
looks like an old-fashioned typewriter.

The Enigma machine.

This is an M4 Enigma machine used by the
German navy during the Second World War.

Every U-boat would have
had one of these machines.

Enigma codes messages in an ingenious way.

Every time the Enigma
operator punches in a key,

one or more of its four rotors
spin to scramble the electric signals.

The chosen key gets encrypted to a different
letter every single time it is pressed.

The variables add up to create a code

with more than 31 trillion
trillion different configurations.

The Germans also
change the machine settings

every day to make the
coding even harder to crack.

One man is determined to break
the Enigma's unbreakable code -

British mathematician Alan Turing.

Turing decides to take on the naval Enigma

because he's a natural problem
solver, he loves a challenge,

and it was a problem
where nobody else was doing

anything about it and he
could have it to himself.

Turing and the code-breaking
teams work around

the clock to decipher
intercepted U-boat messages.

They use a combination of
elaborate code-breaking techniques

and lucky guesses at commonly
used phrases such as "Heil Hitler".

The team breaks the German
army Enigma code in 1941,

but the naval version, code-named
"Dolphin", proves far harder to crack.

Turing designs a machine
to churn through potential

Enigma setting combinations
to speed up the process.

It is a forerunner to the
world's first computer.

Dozens of these machines fill
ever-expanding rows of huts.

Even with their mechanical help, the
code remains stubbornly hard to crack.

What the Allies need is a lucky break.

It is not until the spring of
1941 that they finally get one.

On 9th May that year,
three British destroyers

damage a U-boat just
off the coast of Greenland.

The German captain tries to sink
his own ship, but bungles the task.

The British sailors
manage to climb on board,

where they find a
working Enigma machine

and a code book.

What the German cipher operators
are meant to do is destroy everything,

throw the machine into the sea
and also all of their secret papers.

Everything is printed in
water-soluble ink so that it

will dissolve when it comes
into contact with water.

In the case of U-110, they fail to do this.

The team at Bletchley Park
pounces on the unexpected bounty.

Now that they have the
German code books,

the code breakers can more easily
decrypt the top-secret messages.

The translated codes give them
valuable insight into the U-boat movements,

removing the key element of surprise
from the wolfpack hunting strategy.

The code breakers at Bletchley alert
the command centre up in Liverpool,

where the team is able to divert
the convoys away from the U-boats

and send British forces
to intercept the enemy.

Thanks to the work
at Bletchley Park,

the balance of power in the Battle
of the Atlantic begins to shift.

The German navy never realises the
extent to which its secrets are exposed.

By the end of 1942, the Royal Navy finally
gains an edge over the Kriegsmarine.

Now they plan to take the fight to the
Germans by hunting down the U-boats

and destroying them.

RAF Coastal Command
faces the difficult

challenge of hunting
for U-boats from the air.

At the start of the war, it has to
make do with lightly armed aircraft,

like the Avro Anson, which
only have a limited range.

The Atlantic is so vast
and a U-boat so small,

it is like looking for a
needle in a haystack.

But by 1942, a new aircraft
promises to transform the battlefield.

It is engineered here, at the world's
first purpose-built motor racing track.

This is Brooklands in Surrey, one of the
most famous names in British motorsport.

In the 1920s, its huge oval circuit
hosts the first ever British Grand Prix.

But Brooklands is also home to
one of Britain's oldest aerodromes.

Former Royal Marine Commando
and pilot Arthur Williams

discovers how the racing stops
and Brooklands prepares for war.

I love Brooklands.
Brooklands is a magical place.

In 1939, it was requisitioned
by the Air Ministry and it

really upped its gear in
terms of aircraft manufacturing

and it became a super
powerhouse for churning out

aircraft that we desperately
needed during the war.

Aviation engineers now replace
spectators at Brooklands' famous track.

They become famous for producing
one pioneering plane in particular.

Inside this huge hangar is an aircraft
that makes its mark as a U-boat killer.

The Wellington bomber.

It's fascinating to see the
Wellington here as a whole.

Normally you're used to just seeing
component parts of this aeroplane

because it's one of only two that
are still remaining in this sort of state.

This aeroplane doesn't
look like other aircraft.

It's not designed
in the same way.

The Vickers Wellington is designed at
Brooklands as a long-range medium bomber.

One of the brains behind it is the
maverick inventor Barnes Wallace,

who also devised the Dam
Busters bouncing bomb.

He engineers the
Wellington with a revolutionary

lattice framework called
a geodetic structure.

This makes it light but incredibly strong.
It can still fly with even major damage.

To keep its weight to a minimum, engineers
cover the alloy frame with linen fabric.

Its 19-metre-long fuselage is big
enough to hold eight lethal depth charges,

a type of bomb designed
to detonate underwater.

The Wellington has a disappointing
start to the war as a conventional bomber.

Its limited defences make it
vulnerable to enemy fighters.

But by 1942, it is transferred
to RAF Coastal Command,

where its superior range is
ideal for anti-submarine duties.

The Wellingtons are able to patrol the
Bay of Biscay off the coast of France.

German U-boats, leaving their
bases in ports like Saint-Nazaire,

have to pass through here
on their way to the Atlantic.

The British bombers have a
range of around 1,000 kilometres,

which allows them to
spend hours hunting for the

enemy and still return
home with fuel to spare.

In an aerial attack, the bomber uses
a searchlight to hunt for the submarine

and drops two depth charges,
ideally within six metres of the target.

These detonate underwater,
the shock waves damaging

the U-boat before it can
escape beneath the waves.

The Wellington is also
able to carry an ingenious

bit of kit packed
into its nose - radar.

The Wellington bomber was
an incredibly versatile aircraft.

As radar started to be
developed, it proved itself really

useful in Coastal Command,
searching down the wolf packs.

The radar gave the crew the ability to
see the U-boats beyond visual range,

and then when the crew
knew where the U-boats

were, they could
press home their attack.

The Wellington excels as a U-boat hunter.

It scores its first confirmed
kill on 5th July 1942.

The factory at Brooklands builds more than
2,500 of these aircraft during the war.

But even the mighty
Wellington has its limitations.

The Wellington can only
protect convoys effectively

for around 640
kilometres from the coast

before it runs low on fuel.

Beyond this, the Allied ships enter
the so-called 'Mid-Atlantic Gap'.

In this Nazi-infested danger zone, the
convoys have to sail without air cover,

placing them at the
mercy of the wolf packs.

In 1943, a new American bomber,
the B-24 Liberator, is a game-changer.

Now the Navy finally has an escort plane
with a long enough range to close the gap

and protect the convoys
across the Atlantic.

The new Allied planes
have enough fuel to

spend around a third
of their time in the air

hunting for U-boats
threatening the convoys.

Hitler's submarines are
now caught between the

Liberators in the Atlantic and
the Wellingtons back home.

They suffer appalling losses.

Liberators alone sink 70 German subs.

By 1943, the tables have turned decisively

and the Allies begin to
dominate the battle for the Atlantic.

But the Nazis aren't finished yet.

They plan one last throw of the dice, which
they hope will finally bring them victory.

In 1944, the Nazis rush
out new weapons in a

desperate attempt to
halt the Allied advance.

They develop terrifying
devices, like the fearsome

V-rockets, to swing
the war in their favour.

The German Navy also tries to upgrade
its increasingly obsolete U-boat fleet.

Shipyards like Kiel
build new submarines to

counter the threat from
anti-submarine aircraft.

The chief drawback of the
second World War German

U-boats was they were based
on World War I technology.

They could spend only a
very limited time submerged.

After the Allied had closed the air
reconnaissance gap in the Atlantic,

the U-boats had no
place anymore to retreat.

So the Germans had to
come up with new ideas.

And this resulted in
the construction of the

so-called Elektroboote,
or electric U-boats.

The Elektroboote is powered
by diesel-electric engines.

It could run underwater
at an incredible 17

knots, 10 knots faster
than an existing U-boat,

reducing time spent above the waves.

The U-boats also get new weapons.

Commanders equip their submarines
with heavier anti-aircraft guns,

as well as radar and decoy
balloons to fool the bombers.

But it's not enough.

By May 1945, it's clear that
Nazi Germany has lost the war.

In Berlin, Hitler names Admiral
Dönitz, a committed Nazi,

as his successor before
his own death by suicide.

On 7th May 1945, Germany surrenders,

and all U-boats are ordered
to hand themselves in.

One week later, eight
German U-boats enter

Loch Foyle on the
coast of Northern Ireland.

They head for the Royal
Navy base at Lysa Halley.

It is an extraordinary moment.

Allied warships keep watch,
while fighter planes circle overhead.

But this is no attack.

The Kriegsmarine is
officially surrendering,

bringing the Battle of the
Atlantic to a symbolic end.

Newsreel footage catches the German crews
smiling and joking with each other on deck.

This incredible aerial
photograph reveals rows

of submarines tied up
alongside each other.

By the end of the month, nearly 40 have
arrived in this quiet Northern Ireland port.

The war at sea, which has
cost so many lives, is over.

British demolition experts now rig the
German submarine fleet with explosives.

Many are in poor condition.

Royal Navy ships tow them
out to sea and sink them.

For Britain, the Battle of the Atlantic
was the longest campaign of World War II.

Fought from the very
first day until the last.

Hundreds of ships have
been lost on both sides.

The Kriegsmarine loses 30,000 submariners,

the highest casualty rate of the
German armed forces in World War II.

Dönitz is convicted after the
war, but escapes execution.

He remains an unrepentant
Nazi for the rest of his life.

Today, the wrecks of
many ships and U-boats still

lie in the vast ocean, silent
and unknown war graves.

Testament to the savagery and the
courage of the Battle of the Atlantic.