Original subtitles

One hammer. One bag.

In the years before the Great War, Britain had devoted little effort

to the threat that might one day emerge from German U-boats.

Submarine counter-measures were somewhat less than sophisticated.

Small boats were to patrol the coast.

In the event that they saw a submarine,

or rather saw a submarine's periscope,

they were to follow one of two suggested strategies.

Strategy number one - smash the periscope's lens with their hammer.

Strategy number two -

cover the periscope's lens with their bag.

Early submarines were not taken seriously.

One British Admiral called them "playthings".

The coming war, it was widely believed,

would never be won by submarines.

It would be won by big battleships and big guns.

But after the Battle of Jutland,

by the first week of June 1916, the battleship war was over.

The surface warships of the Imperial German Navy

would scarcely leave harbour again.

But as the dreadnought war ended, the U-boat war intensified,

dramatically.

Germany's growing fleet of submarines

was ordered to wipe out British shipping.

We were losing 12 ships a day.

And we couldn't possibly replace 12 ships a day.

Britain was forced to develop devious

and deadly strategies to defeat the U-boats.

The German U-boats were no-one's "playthings".

They brought Britain to the brink of surrender.

Ten weeks into the war, at midday on the 18th of October 1914,

the cargo ship Glitra departed Grangemouth harbour on the River Forth.

She headed east, under the famous bridge and out to sea,

bound for Stavanger in Norway.

On board she carried a cargo of coal, iron and oil.

Two days later and 14 miles off the Norwegian coast,

she was ordered to stop by a surfaced German U-boat,

the U17.

The Germans came on board

and ordered the crew to get into their lifeboats.

Then they went below decks to open up the seacocks,

to begin scuttling the ship.

Finally, and amazingly,

the Germans began to tow the lifeboats

towards the Norwegian coast.

The ship and its cargo lay at the bottom of the ocean,

but no-one, absolutely no-one, had been hurt.

It was all very gentlemanly,

but the Glitra had just become the first British merchant ship

to be sunk by a German U-boat.

This was the first European submarine conflict,

and the international rules of war were struggling to keep up.

The laws of war were written in the late 19th century

to protect civilians. It made a big distinction

between those in uniform who were warriors,

and those who were civilians and could not be attacked,

in which case the submarine had a duty to come up,

make itself apparent,

warn the merchant ship that it was going to be attacked,

give the merchant ship time to get the civilians off -

the crew and the passengers -

so that when they sunk the merchant ship, no lives would be lost.

I believe they were called prize rules.

They were called prize rules - that was the laws of war rule.

They were called prize because the ship is a prize.

If you look at it historically, of course,

they're a prize because you want to take the cargo on board.

Two weeks after U17 had sunk the Glitra and her cargo,

Britain's First Sea Lord made a stark announcement to the international press.

On the 2nd of November 1914, Admiral Fisher stated

that the Royal Navy was assuming military control

of the entire North Sea.

The Germans reacted of course with outrage and shock,

as if all Britain was doing was making clear the state of naval play at the time.

When it came to the surface of the oceans, the British Navy

had won the naval race from before the First World War.

It could say what could travel

on the top of the seas.

If the Royal Navy controlled the surface of the ocean,

is that what prompted the Germans to develop their submarine fleet?

The submarine was actually developed by the Germans relatively late.

I mean, they weren't the first people to develop the submarine.

The submarine comes out of the American Civil War,

when it's developed by the South,

but it's the weapon of the smaller naval power against the larger naval power.

That's the way to understand it.

The larger naval power, Britain, had moved its navy to east coast bases.

From there, it could patrol the North Sea,

and seize cargos bound for German harbours.

For their part, the German U-boats would attempt to evade

those British patrols and hunt for incoming British cargo ships.

In 1914, Britain imported two thirds of her food supplies.

Also cotton for uniforms, timber for trenches and iron ore for guns.

If the U-boats could sink enough British merchant ships,

Britain could not remain at war.

Germany's U-Boat fleet was small but its threat was real,

and deadly.

U-boats cruised on the surface.

They could stay at sea for five weeks,

and would attack undefended ships with their forward gun.

They dived to attack bigger and better defended ships with torpedoes.

Each U-boat carried at least six.

Ironically, the early inspiration for these hunter-killer submarines

had come from Germany's future enemy.

It was the British who made popular the submarines

all over the world, in the first years of the 20th century.

Who used small coastal submarines as defensive weapons,

as cheap defensive weapons, for coastal and harbour defence.

But the development of the motor, especially the diesel motor,

gave this new weapon a much longer range, so the submarine changed

from coastal defence to a long range offensive weapon.

What was life like aboard a German submarine?

The submarine was full of machinery, of weapon systems,

torpedo tubes, diesel electric motors, ammunition, and so on.

It was smelling all the time, diesel, gas.

The boat was wet inside so there was always some water coming in,

when it was surfaced and so on.

It was quite a stressing life for people on board.

U-boats began the war following the gentlemanly prize rules.

Rules that had saved the crew of the Glitra.

But on the 4th of February 1915,

at the naval base here in Wilhelmshaven,

the German leader Kaiser Wilhelm

signed an executive order that tore those rules apart.

In translation it read,

"From the 18th of February onwards, all enemy merchant ships

"in the waters surrounding Great Britain and Ireland

"will be destroyed, irrespective of the impossibility

"of avoiding in all cases danger to passengers and crew."

The polite war was over.

The U-boat war had begun.

It would be called unrestricted submarine warfare.

Now, the men and boys who crewed British cargo ships

and British liners were placed directly in the line of fire.

And just three months after the Kaiser's announcement,

British crewmen and British civilians would pay the ultimate price.

On the 7th of May 1915,

the Imperial Germany Navy had six U-boats at sea.

Five in the waters around Scotland.

And one, the U20, south of Ireland.

Her captain, Walter Schweiger, had three torpedoes remaining.

At 1.20pm,

Schweiger saw a large four-funnelled passenger ship.

What happened next would generate international revulsion

against German U-boats,

and would be felt in communities all across the world.

So, Oliver, who are these individuals in the photographs?

Well, this is James Aitken as a young man.

Chrissie, who was the daughter, a 17-year-old,

- was on deck with friends. - Is this Chrissie here?

This is Chrissie, yes.

Oliver Russell is a distant cousin of Chrissie Aitken.

The family had emigrated to Canada in 1912,

but when Chrissie's father fell ill in 1915,

they headed back to the family farm at Innerleithen.

They booked a ticket. I gather they booked a ticket in Chicago,

so they probably travelled by train across Canada.

They booked a ticket on the Cameronian,

which was due to sail from New York on May 1st.

In New York, the Cameronian was requisitioned

by the British Government.

The Aitkens were transferred to another liner.

The Lusitania.

Built in Clydebank in 1906,

she had once been the biggest ship in the world.

On the 1st of May, she departed for Liverpool

with almost 2,000 people aboard.

Passengers had been warned by German notices in American newspapers

that they were sailing into danger.

Six days out of New York,

at 3:10pm in the afternoon of the 7th of May,

at a distance of 765 yards,

Captain Schweiger targeted the ship in his periscope

and fired a single torpedo.

Chrissie was on deck with friends,

whereas the others, the three others,

were downstairs finishing their lunch.

The torpedo hit the ship.

There was an explosion, there was a lot of smoke, a lot of dust.

Chrissie rushed down from the deck to try and find her family,

couldn't find them, and came up again to try to find what next to do.

Chrissie sounds to me a remarkably quick-witted young woman.

- Very brave. - Those are acts of great courage

from someone so young - a 17-year-old girl.

Chrissie didn't find her family.

She abandoned ship and made it ashore.

The next day she was asked to identify her father's body.

Captain Schweiger's single torpedo claimed 1,198 lives.

including Chrissie Aitken's father, brother, and his infant child.

128 of the victims were from neutral America,

and American outrage forced the Kaiser to end his campaign

of unrestricted U-boat warfare.

But sinking the Lusitania had been a deadly demonstration

of the potential of Germany's tiny U-boat fleet.

So for the British, new techniques for anti-submarine warfare

had to be developed, and quickly.

Cruising on the surface as they generally did,

U-boats could be shelled, or rammed.

Hitting them underwater was more difficult.

In 1915, the Royal Navy introduced depth charges - underwater bombs.

But the question remained of how to detect submerged submarines

in the first place.

In search of an answer, in the summer of 1915,

the Admiralty established a research station

here at Aberdour on the Forth.

To develop what became a precursor to modern day sonar -

the hydrophone.

A hydrophone attempts to listen to sound underwater.

it's a receiving microphone

in a waterproof casing, so that they can put it underwater.

When a noise - a sound - comes,

a sound wave will hit the diaphragm.

It will cause it to vibrate, and the vibrations turned into a sound

that you will be able to hear.

So they picked up the pulse and the throb

- from the engines of the submarines? - Yes, yes.

In charge of the hydrophone research at Aberdour was Captain Cyril Ryan.

He assembled an unlikely team that included top scientists,

Nobel Prize winners, and...

soprano singers.

The hydrophones were used in pairs on the boats

so that they could be used by a trained ear to locate

where the enemy submarine might have been.

They wanted to put them so that it was low for port

and high for starboard, and so they thought the best people

to do that, and I'm sure the musicians were delighted,

were the top musicians of the day.

So they had a Hamilton Harty,

who was in charge of the Halle Orchestra,

and his wife, who was Agnes Nichols, and she was a famous singer.

And they sat amongst all the hydrophones here - probably here -

and they had to get them into piles,

low for port and high for starboard,

and they used a hammer to tap the diaphragms

and they got them into pairs that way.

In the war against the U-boats, no idea could be dismissed,

however eccentric, however underhand.

The Admiralty demonstrated precious few scruples.

Painted in tribute to the "dazzle ships" camouflage

of the Great War, this ship is the last surviving example

of a dastardly form of British warfare

that all began in 1915.

Built in Renfrew, HMS President was a Q ship,

a class of vessel designed to look like an unarmed cargo ship,

and to trick U-boats to the surface,

where a Royal Navy crew would be lying in wait.

They would disguise themselves as a merchant ship crew.

Of course, they would get rid of any idea of naval uniform,

any idea of naval discipline.

They would be unshaven, untidy.

They might even have some people disguised as women,

to pretend to be the captain's wife and family,

patrolling about the deck as well,

and they would look as shambolic as possible,

nothing like a naval crew.

And I've read that some of them would wear dressing gowns

on board the deck, or they'd carry budgerigars in cages

and things like that. Yes, I think they did do things like that.

I think it reflects the Royal Navy's opinion of the merchant navy

as much as anything else!

They thought that was what the merchant navy was like.

This 1928 film, The Q Ships,

offers a dramatized portrayal of a Q ship in action.

On sighting the periscope of a U-boat, the ship's crew

behaved in a rehearsed panic and took to the lifeboats.

All to convince those on the U-boat

that the ship was perfectly harmless.

They would hope the German submarines would surface

and try to sink them by gunfire.

Torpedoes were very expensive things. It was much simpler

to get up on the surface and sink the ship by gunfire.

As the U-boat approached,

a hidden crew remained waiting on board the Q ship.

At the last moment, the crew hoisted the white ensign of the Royal Navy.

The innocuous cargo ship was officially, if a little belatedly,

transformed into a Royal Navy gun boat.

You would hide the guns between barricades,

you would drop these when the U-boat appeared

and then you would fire on the U-boat.

The war that had begun with the gentlemanly prize rules had,

within a year, descended into the horrors of the Lusitania

and the deceit of the Q ships.

The next year, 1916, began with the Kaiser's second campaign

of unrestricted submarine warfare.

A campaign that ended in international outrage

when the ferry Sussex was torpedoed by UB-29.

50 passengers were killed.

1916 would be better remembered

for the epic but inconclusive Battle of Jutland.

Then just three days later

for an infamous trap laid by one U-boat, U75.

On the 4th of June, the Secretary of State for War,

Lord Kitchener, arrived at Scapa Flow

en route to a top secret meeting in Russia.

He was applauded on board HMS Iron Duke.

He met and had lunch with Admiral Jellicoe,

the commander in chief of the Grand Fleet.

Kitchener was a national icon, Britain's favourite soldier.

That afternoon, aboard the Iron Duke, the weather closed in.

Jellicoe suggested to the Secretary of State

that he delay his journey,

but Kitchener was having none of it.

Soon after 4pm, Kitchener returned to the deck of the Iron Duke.

The moment was recorded in this - his last known photograph.

At 5pm, his ship, the Hampshire,

set out with an escort of two destroyers.

Jellicoe had ordered that they sail to the west of Orkney,

to shelter from the storm.

But unknown to the British,

submarine U75 had already paid a visit.

The sea condition and wind were such that the destroyers

couldn't keep up, so the Hampshire reluctantly sent them back to Scapa.

So she was steaming on her own.

And she reached here just before 8 o'clock at night

and ran into a string of mines that had been laid

by a U-boat, the U75.

And she hit at least one mine, more likely two chained together.

They set off at least two explosions on board the ship, possibly three.

Keeled over fairly quickly and sank within 15 minutes.

She managed to get three life rafts away

and nearly 200 mostly young, fit sailors scrambled on board,

before the ship went down.

Some of them managed to reach up the beach,

and basically that's as far as they got before they died from exposure.

- Did the lifeboat take to sea? - No, the Stromness lifeboat

was manned, and the crew were ready to go

and asked permission from the navy to do so, and it was refused.

- Do you know why? - The navy's view was that they had plenty

of boats of their own and that they would do it themselves.

They sent out an armed yacht and a trawler,

followed 15 minutes later by four destroyers,

including the two that had left the Hampshire before.

These ships never picked up anyone.

By then, the rafts had been driven down the coast

and nobody was picked up directly from the sea.

Amazingly, two young English sailors made it ashore at this farm.

Inside were Jim Sabiston's grandparents

and his 20-year-old mother.

It was quite dramatic, this bedraggled sailor at the door,

and then she shouted on her man to come

and her daughter, my mother, shouted on them.

They got up and got the fire going,

and boiled a kettle. There were no electric kettles in those days.

They boiled a kettle and got tea and something to eat

and got them to bed.

They got some of my grandfather's clothes to put on, I think,

and put to bed, and they were there till morning.

But in that time, my grandfather had gone out

and gone to the next door neighbours'.

They came down to the shore here,

and they had ropes with them and my grandfather went down

with a rope round his waist and they took up three more survivors.

He went down on a rope over the cliff?

Yeah, and they took up one at a time till they got three of them up.

Jim's grandfather and his neighbours had saved three lives.

But, for reasons that remain unclear to this day,

they were ordered to stop.

Conspiracy theories have persisted,

and in particular that the naval authorities valued the secrecy

of Kitchener's papers more than they valued the men of the Hampshire.

My grandfather and them

were stopped from doing anything more.

To try and rescue any more.

- Who stopped them? - I think it was navy.

Officials came up from Stromness or somewhere.

And stopped the local people going to help the survivors.

Yes.

So were there a lot of dead bodies swept onto the beach?

Yes, yes. They carted them off in lorries.

The next day, they were carrying them up in lorries.

No sympathy at all. They were just thrown on the lorries,

just the bodies.

Terrible. Terrible story.

From Hampshire's crew of over 700, only 12 survived.

Kitchener's body was never found.

One U-boat and two mines had sunk the Hampshire

and placed Britain in a state of national mourning.

One thing was clear.

Britain's warships needed even greater protection from German U-boats.

Built in Birkenhead in 1914,

the British light cruiser HMS Caroline is the only ship

still afloat that saw action at the Battle of Jutland in 1916.

Back then, her first line of defence

was the poor soul keeping watch on top of the tripod mast.

Now, I'm about to climb up to the lookout point way up there.

I've got a safety harness on.

Can you imagine doing it in freezing cold weather, out on the high seas,

when the boat is rocking?

Not a lot of laughs.

As the Great War began, getting to an elevated position

was the still the best way of spotting enemy ships and surfaced U-boats.

A technique that hadn't changed much since Nelson was a boy.

Can you imagine what it'd have been like, during the Great War,

you're part of the British Grand Fleet,

you're fighting the German High Seas Fleet.

Shells exploding all round you,

crashing around in 20-foot-high waves.

You don't know whether you are going to live or going to die.

There's smoke and mayhem.

Torpedoes coming at you.

It must have been truly, truly terrifying.

Not for wimps like me. That takes real men.

From 100 feet up,

a lookout could see for a distance of around 12 miles.

But from 1,000 feet up,

an airman could see a distance of almost 40 miles.

And so, to protect British ships,

a fantastic assortment of primitive aircraft took to the skies.

At Scapa Flow, over 1,000 men were involved

in the aerial defence of the Grand Fleet,

now under the command of Admiral Beatty.

On patrol, Beatty's ships were accompanied by powered airships,

or blimps, based at Caldale, just west of Kirkwall.

Caldale was also the base for an even more terrifying form of early aviation.

Unpowered two-man kite balloons attached by a single lifeline

to the deck of a warship.

They could go up to about 3,000 feet

and be towed along at about 20 knots.

It's quite hazardous, of course,

because they were subject to weather,

and there were one or two lightning strikes, and there is one report,

that I don't think is apocryphal,

of a balloon that simply snapped and was never seen again.

Dear Lord.

- That's a really scary occupation, isn't it? - Yes. - Very hazardous.

There is one very telling photograph of the crew of a kite balloon,

and we have a close-up of the main observer

and he is looking extremely nervous.

THEY CHUCKLE

In modern day aviation, Orkney is world famous for this.

The world's shortest scheduled flight.

About two minutes from Westray to Papa Westray.

But Orkney has another claim to aerial fame.

A year after Jutland, 25-year-old Squadron Commander Edwin Dunning

climbed into his tiny Sopwith Pup biplane, and took off.

Aircraft had long been able to operate from moving warships.

After their flight, they would touch down on the sea, or on land.

Landing back on the warship itself presented a monumental challenge.

Over Scapa Flow, Commander Dunning manoeuvred his aircraft

towards HMS Furious, and her 220 foot runway

designed for taking off - not landing.

- It was doing something like 25, 26 knots. - Pretty fast.

Into a headwind. Commander Dunning faced considerable difficulties

avoiding the entire superstructure of Furious,

and having to drop his Sopwith on to this

forward deck, with very little room to spare.

This is a photograph of that famous attempt

by Commander Dunning to land on HMS Furious.

And it looks one of the most dangerous

and scariest adventures ever, not only for Commander Dunning

but also for the officers and men of HMS Furious,

who attempted to grab hold of his flying aircraft.

The second photograph

is just after he'd completed his landing,

surrounded by men. It must have been a wonderful moment for him.

The congratulations of the men all around him,

because he had done something that no-one else

had ever done in the world before.

And the third photograph is taken five days later,

when unfortunately he slipped off the front of HMS Furious

and into the water. Now the ship would have been

steaming ahead at 26 knots. By the time they turned around

and got back to where the Sopwith Pup was, Commander Dunning was dead.

Days later, in a letter to Dunning's mother, the Admiralty paid tribute

to his bravery, and stated that Dunning's pioneering landings

at Scapa Flow would make aeroplanes indispensible to the fleet.

On the 31st of January 1917,

Germany announced a new campaign of unrestricted submarine warfare.

Her third.

But now she had over 100 long-range U-boats.

This would become known as the killing time.

From the very next day, the 1st of February 1917,

all ships suspected of carrying goods to Britain

were to be sunk on sight.

Without warning, without mercy.

For the men of Britain's merchant navy,

the next few months would be the most terrifying yet.

For Germany, unrestricted U-boat warfare was the only chance

to take Britain out of the war.

Her surface fleet had missed its chance at the inconclusive

Battle of Jutland the year before.

The German war effort and the German people

were both being starved by the British naval blockade.

Jutland had proved to the Germans that they could not challenge the Royal Navy in the North Sea.

Therefore they could not break through the economic blockade,

therefore they had to find other means of knocking Britain

out of the war.

The navy high command promise that they can sink about 600,000 tonnes

a month of Allied shipping.

In April, they exceed that, by some margin.

They sink nearly 850,000 tonnes of Allied shipping in one month alone.

- In one month. - That's a huge number.

April 1917 was the cruellest month,

with a staggering 516 ships lost to U-boats.

Henning von Holsendorf was the commander of the navy,

and was really the driving force behind the submarine campaign.

He's made a very rough calculation. If the German U-boats

sink about 600,000 tonnes of Allied shipping,

that exceeds Britain's capacity to rebuild ships,

and he reckons that within the first six months, he would have sunk

about 39% of British shipping, and that would be the point

when the British would simply not be able to carry on in the war.

In April 1917, in a letter to the war cabinet,

Britain's First Sea Lord, Jellicoe, stated,

"We are carrying on this war as if we had the absolute command of the sea.

"We have not and have not had for several months."

He underlined, "Our present policy is heading straight for disaster."

In June 1917, Jellicoe told the war policy committee

that owing to the shortage of shipping

it would be impossible for Britain to carry on the war into 1918.

The British crisis became German propaganda.

This 1917 documentary,

The Enchanted Circle, chronicled the successes of a single German U-boat

operating against British shipping in the Mediterranean.

The film in all is 40 minutes,

and 25 is sinking English ships one after the other.

It was shown in Germany in Autumn of '17.

It was not a big success because the public got bored.

One ship sinking after the other and always the same.

I think there are a dozen filmed scenes about ships sinking here.

Yes, that's nice propaganda.

The commander gets Lloyd's book of ships

and he strikes out another English one - one after the other.

Very impressive for the home front.

This boat alone sank over 200 British and neutral ships.

Good Lord.

This is nice film music.

It's really adapted to each shot.

This is heartbreaking for ship lovers,

it's a nice sailing ship going down.

So sad.

Miss Morris, English ship.

Why if she wasn't carrying anything?

Or just because...

Carrying olive oil, wine, or something like that.

Some cargo which was not really urgent.

Coal, even. Coal ships.

For British merchant sailors, these were truly terrifying times.

For every four British merchant ships that set out

on a return international journey, only three would return unharmed.

We were losing 12 ships a day.

A day!

To U-boats, and we couldn't possibly replace 12 ships a day.

And we were down to three weeks' food supply,

and Jellicoe couldn't see a way round it.

The answer, of course, was the 18th century solution of convoying.

But Jellicoe was dead against convoying,

A, because it was a historical thing that he didn't think

could apply in the 20th century, B, there were technical reasons

why merchant ships can't keep station in a compact fleet.

They are not designed to sail in company.

Also there was an element of snobbery,

that these merchant ship captains were usually rather scruffy men

in ill-fitting suits and bowler hats.

"They can't behave like naval officers, can they?"

A convoy has tremendous advantages, mathematical advantages,

over a U-boat.

And if convoys are escorted, U-boats can't attack on the surface,

using their guns - much more cheap than using torpedoes.

After the introduction of convoys, in May 1917,

the number of cargo ships lost to U-boats fell dramatically.

Indeed, the biggest casualty of the new convoy strategy

was the man who had opposed it, Admiral Jellicoe.

Chosen by Churchill to command the British Grand Fleet

in the first days of August 1914,

Jellicoe was effectively sacked on Christmas Eve, 1917.

A lot officers in the Navy were scandalised

because he was their hero, but quite a few breathed a sigh of relief -

"Now we can get on with winning this war."

And from April 1917, Britain would have a new ally.

Frustrated at the loss of her ships to the German U-boats,

the United States entered the war.

Her dreadnoughts sailed to Scapa Flow,

and in the seas east of Orkney,

American naval engineers laid out plans for one of the most ambitious

and grandiose projects of the entire campaign.

This was a truly amazing scheme -

a minefield, hundreds of miles long,

between Scotland and Norway.

In 1917, planners here at the US Naval Academy

estimated it might cost 200 million -

the equivalent of £10 billion today.

You have to realise what the United States was in 1917 -

it was the place where things were mass produced.

So when we thought of a contribution to the war, we thought numbers.

And very early in our entry into the war,

someone said, "Well, look, you want to deal with these subs,

"seal off the end of the North Sea

"so that they can't get out into the Atlantic."

Part of it is we're going to be running troop ships

across the Atlantic with the army - that's our biggest contribution.

How do you protect them? Put in a gate.

Now I believe one of the most passionate advocates

of the barrage was a future US President.

Roosevelt was Assistant Secretary of the Navy.

That means he was responsible for procurement.

It wasn't invented by Roosevelt,

it was invented by someone in the Bureau of Ordnance,

who went to Roosevelt and said, "Look at this."

And Roosevelt said, "Yes, yes!"

And then he becomes the main advocate, and he sells it

internally in the US Government.

They also sell it to a British Admiralty that believes it's idiotic.

How did he manage to sell it? I mean, I've read estimates,

conservative estimates, that it was going to cost a minimum

of 200 million. That's a hell of a lot of money, isn't it?

Once we get in the war, there's a lot of money.

And there's also a very strong desire

to do something decisive that will end things.

And if it's 200 million, we had the money.

We were a very rich country at that time.

The plan called for the production of 70,000 mines,

of which 50,000 would be manufactured in the United States.

There was a naval gun factory in Washington

that did most of the ordnance work. I suspect that they did the mechanisms.

The casings were probably out of Detroit -

that would have been where you got mass production.

- In the car factories? - Yeah.

You convert the car factories to other things.

That was a major American resource, and we used it.

Components were delivered to the Norfolk Navy Yards,

then shipped across the Atlantic and along the Caledonian Canal.

The mines were finally assembled in converted whisky distilleries

in Inverness and Invergordon.

We also modify a fair number of ships to lay the mines.

The Royal Navy covers the minelaying operation,

but the minelayers are American.

The finished minefield comprised multiple overlapping layers.

It ran from the east of Orkney across the North Sea

to a position just north of Stavanger in Norway -

an approximate distance of 270 miles.

Under the surface, mines were sown at three depths down to 240 feet -

well below the maximum operating depth of a U-boat.

Each mine contained 300 pounds of explosive.

And the deeper mines had new, top-secret antennae

that would detonate on contact with a U-boat.

In total, 70,263 mines were sown.

The project was completed in the Autumn of 1918,

just as the German war effort was finally collapsing.

So there's a real question as to how much sense it made.

In the US Navy of that era, you're looking at a navy

that hasn't quite matured to the point where

people automatically think about these things.

The Royal Navy is a much more mature navy, obviously, and that shows.

A lot of the effect of World War I on the US Navy

is we thought we were really good before the war.

We were sure we were just right up there.

And we discovered we weren't.

And that was a very salutary thing.

For all the cost - the equivalent to £10 billion today -

only six German U-boats have been confirmed

as casualties of the minefield.

The first casualty was U92.

On board was Assistant Engineer Wilhelm Koerver,

Hans Koerver's great uncle.

The boat has been found south of the Orkneys

in 80 metres depth, with...

I saw some nice sonar pictures of the boat -

it's quite intact. I contacted some divers who had gone down to there.

They say the hull is nearly intact, so I assume it had been hit

in the distance by a mine which had destroyed the diving tanks

so it went down. And it's still intact,

so all the crew, my great uncle and his comrades,

are still lying there since nearly 100 years, now.

Hans, when we think...

Well, certainly when I think of the First World War,

you have very brutal, visceral images of men dying in the trenches,

in the most horrific circumstances, and we very rarely think about

the submariners and the sailors who died

in probably equally horrific circumstances at sea.

About two thirds of the submarines were sunk in the end.

I think half of the submariners, around 6,000, 8,000 men,

that served on board the submarines were drowned with their boats.

I found a story of a submarine which was sunk into the ground

but the crew was still alive and the water was rising inside,

and the first ones got out pistols

and tried to shoot themselves, but the pistols had gotten wet.

Others were trying to suffocate themselves

by throwing something in their mouth.

The eyewitness who had seen this,

later he was able to escape by the torpedo tubes,

so never anybody talked about this,

but there seems to have been some kind of consensus -

"So, what will we do in the case our submarine is lying on the ground,

"will never go up again? We will slowly suffocate."

I think there was a consensus, there were weapons on board,

pistols, to shoot themselves.

The German U-boats had their final shot at glory in October 1918.

UB116, carrying 11 torpedoes,

headed into Scapa Flow.

Since 1914, this had been the primary base

of Britain's Grand Fleet, her mighty dreadnoughts,

commanded by Admirals Jellicoe then Beatty.

At Hoxa, the southern entrance to Scapa Flow,

the engine noise of UB116 was detected by hydrophone.

Technology pioneered at Aberdour

by Captain Ryan's team of scientists and singers

fixed the exact location and depth of the U-boat.

EXPLOSION

UB116 was destroyed by an electronic mine.

Her target, the British Grand Fleet, was 200 miles to the south.

Their new commander, Admiral Beatty,

had transferred the entire fleet to the Forth,

so this final U-boat attack had been a deadly and pointless failure.

At Wilhelmshaven, the sailors of the High Seas Fleet mutinied.

Their revolution spread across the country.

The Kaiser abdicated.

On the 11th of November 1918,

the land war ended with the Armistice of Compiegne.

The sea war would end four days later - in Fife.

The representative of the Imperial German Navy, Admiral Meurer,

arrived on the Forth on board the German cruiser Konigsberg.

Accompanied by his staff officers, Meurer was taken to Rosyth Dockyard,

where they boarded HMS Queen Elizabeth,

Admiral Beatty's flagship.

Her modern namesake now dominates Rosyth.

In Admiral Beatty's cabin on board the old HMS Queen Elizabeth,

Beatty met Meurer and the German officers.

They sat opposite each other at a long table,

while Beatty dictated the terms of the naval armistice.

There's a very famous painting of this by Sir John Lavery,

and the British actually had Sir John Lavery in naval uniform

so he could sit in the room without the Germans knowing

there was an artist in there to record this moment.

And essentially Beatty read the terms

under which the German fleet was to be interned.

The victorious allied navies each had a right

to a share of the ships of the German Navy.

That share had to be determined, and until it was,

the vessels would be kept in British waters.

The first to arrive were the German U-boats.

On the 20th of November 1918, they sailed into Harwich.

As they arrived, British crewmen

were ordered not to cheer in victory.

The crews were dispatched back to Germany,

leaving their submarines behind.

At the end of four years and three months of war,

the German U-boats had sunk over 5,000 ships.

The German surface fleet surrendered the next day,

the 21st of November.

HMS Queen Elizabeth headed out to meet the German ships.

Admiral Beatty acknowledged the cheers.

Way out at the mouth of the Firth, 40 miles off the Isle of May,

the German surface fleet steamed in, and the allied fleet - which was

the British Grand Fleet, there was an American battle squadron,

there were some French representatives -

370 ships in two lines, waiting.

And the Germans came and steamed in between them.

Initially the atmosphere was very tense.

The German ships had been de-ammunitioned

and the breechblocks had been removed from the guns -

that was part of the terms of the armistice.

The British ships - the guns weren't loaded,

but they were ready to load and the crews were at action stations,

because no-one really knew. There was a possibility,

there was a risk, that there may be some gesture of defiance.

And they anchored below Inchkeith,

which is the island you can just see silhouetted on the horizon there.

People came out. People came out in boats.

I was going to say,

- it must have been quite a spectacle... - Extraordinary

sight. - ..for the local people to watch.

This is the dramatic downfall of German power,

so people came out for a closer look.

There was no sense of honour between foes, either.

There was a sense of contempt for the German Navy,

that they had stayed in harbour, they had relied on submarine warfare,

which was considered to be dishonourable, ungentlemanly warfare.

So the British had sense of disgust, almost, at the Germans.

So Admiral Beatty said that he ached, they all ached,

to give them a dose of what they had intended for them.

Beatty's signal officer described the scene as being like

attending the funeral of some very sordid person who had been murdered.

HE LAUGHS

And then Beatty sent the signal out that at sunset

the German ships should lower their flags and not raise them again,

and that was the finish.

Over the next few days,

the German surface fleet was escorted to Scapa Flow.

The great natural harbour where the British fleet had begun the war

was where the German fleet was ordered to end the war.

Under the command of Admiral von Reuter,

the frustrated, hungry and ill-disciplined sailors

on board the 74 German ships

awaited the outcome of the Paris peace talks.

And after seven months, the Admiral's patience ran out.

At 11:20am on the 21st of June 1919,

Reuter sent a signal from his flagship, the Emden.

The flags read: "Paragraph 11. Confirm."

That was the cue to scuttle the entire fleet.

At 12 noon, as they settled lower and lower in the water,

each ship hoisted the colours of the Imperial German Navy.

It's a matter of your honour as an officer.

You don't hand over your ships.

You either go down fighting with your ship,

or you make sure that your enemy doesn't get it.

As German crewmen took to the lifeboats,

flying white flags of surrender,

some were confronted by British sailors and marines.

As the events unfolded, a British war artist,

Bernard Gribble, looked on.

So it looks like there are three white flags of surrender

on these small boats, and you've got British sailors

and an officer up there, training guns on them.

Gribble recorded his eyewitness account

in both painting and prose.

He had stuck this description onto the back of the painting,

so there's no doubt about what's going on. He says,

"In a few moments the vessel began to sink,

"and our men were ordered to open fire on the approaching crews

"as they refused to return to the ship.

"The German officers were very daring,

"actually coming alongside our boat,

"and arguing their right to be taken on board.

"They smoked cigars and wore yellow kid gloves all through the incident.

"They suffered losses among their men, as several were shot down."

This picture does not portray our finest hour,

if you have British seamen ready to fire on unarmed,

white flag of surrender-waving Germans.

It wasn't publicised that this had occurred.

There's some confusion - I mean, accounts vary,

but Gribble is quite clear,

and he was quoted in the press internationally afterwards,

that the men in the boats were fired upon.

So it's not something that the Admiralty

and the British Government dwelled on.

But this was an act of war, the armistice terms had been violated.

By scuttling the ships, they were breaking the armistice terms.

Absolutely. I mean,

they raised their ensigns. They were considered to be a legitimate target.

The Germans killed in the summer of 1919 are buried

alongside more than 400 British sailors

here at Lyness Cemetery on the island of Hoy.

These gravestones mark the final casualties of the Great War,

seven months after the armistice.

To this day, the waters of Scapa Flow

are home to remnants of the Imperial German Navy.

For their deadly enemy, the Royal Navy,

this great natural harbour had been home for four years.

But by the end of 1918, the Royal Navy had returned

to the home comforts of Portsmouth and Plymouth.

But the battle had been won here.

From Scottish harbours, and on northern seas.