This programme contains scenes that some viewers may find upsetting.
In August 1914,
the two greatest navies in the world made ready for war.
Now the Royal Navy will settle the question of the German fleet,
and if they do not come out and fight,
they will be dug out like rats from a hole.
But the two fleets rarely met.
Instead, a new kind of war evolved, more stealthy, more cruel.
A war not against battleships, but people.
The world's capital ships in 1914 were the products of a cold war.
Britain's HMS Dreadnought had set the benchmark -
heavy armour, big guns, fast.
Dreadnoughts were bargaining chips in a great naval poker game.
Germany had 13, and seven building.
Austria-Hungary, three, America, ten,
Britain, 20.
They kept the peace, but then the cold war turned hot.
Britain and Germany were the main opponents,
staring each other down across the North Sea.
The longer they looked at the map, the more obvious their problems.
Germany's ships couldn't get clear of the North Sea.
To the south, the Channel, blocked by mines and the Dover Patrol.
To the north, the British Grand Fleet at Scapa Flow.
But Britain couldn't get at the German fleet
unless it came out from its heavily protected bases.
And if they actually met in the North Sea,
the result could be catastrophic.
The sight everyone feared.
Austro-Hungarian battleship the Istvan,
sunk late in the war by a tiny Italian torpedo boat.
In 1914, the German navy believed torpedoes and submarines
might tip the balance their way.
A hit-and-run war with little history and no rules.
Jackie Fisher, Britain's sharpest admiral, predicted radical change.
The use of submarines has convinced us
that in wartime, nothing can stand against them.
The submarine is the coming war vessel for sea fighting.
It means the whole foundation of our naval strategy has broken down.
Two days into the war,
Germany unleashed ten U-boats into the North Sea
to hunt down the British fleet.
One of them, U21, made her way to the Firth of Forth,
where the British cruiser HMS Pathfinder
was leaving Rosyth naval base.
U21 sunk her with a single torpedo.
Within a fortnight, the Germans had more good news.
This 1927 film celebrates the voyage of Captain Weddigen and the U9.
Through my prismatic glasses,
I noticed a small masthead come into view near the Maas lightship.
It looked like a mast of a warship.
Could it be the first sight of the enemy we were to have in the war?
The U9 had found the British cruisers Hogue, Aboukir and Cressy
on patrol off the Dutch coast.
Practically obsolete, they were nicknamed the Live-Bait Squadron.
Captain Weddigen seized his chance.
Fired torpedo at 500m.
Target was middle ship in a three-ship formation.
31 seconds later, the torpedo struck Aboukir.
On board was Kit Musgrave.
We were woken by a terrific crash.
The ship shook and all the crockery in the pantry fell.
Cressy and Hogue arrived and let down their boats.
Then Aboukir went down and we slid down her side into the water.
Musgrave jumped into the North Sea
and became the only man in the war to be sunk on three ships
within one hour.
I swam to the Hogue and was going on board
when she was struck and sank in three minutes.
I then swam to the Cressy and was hauled up the side,
but she was struck also and we sank.
Georg von Muller was chief of Germany's Imperial Naval Cabinet.
On our return from the morning ride,
the first news of the successful torpedo attack by the U9
on three English cruisers.
We are all delighted and the Kaiser is in seventh heaven.
The British were appalled.
First Lord of the Admiralty Winston Churchill got the blame.
Over 1,400 men, many of them cadets,
had died in a single submarine attack.
Winston's War Babies, they were called.
British submarine lieutenant Ronald Trevor wrote to his parents.
The news tonight is sad,
but what we submariners have been expecting for weeks.
The commodore has repeatedly warned the Admiralty
that those ships ought not to patrol the North Sea.
What happened is what we predicted -
ships standby to rescue the sinking one's crew,
then the submarine gets two sitting shots.
Commander-in-chief of the British Grand Fleet
was Admiral John Jellicoe.
He'd joined the navy in 1874 as a midshipman.
ADMIRAL IS PIPED ABOARD
Known as Silent Jack, he was experienced, capable and cautious.
He ended patrols off the German coast,
confining his most valuable ships to Scapa Flow and Rosyth,
the limits of the U-boats' range.
He warned the Admiralty.
The Germans rely to a great extent on submarines, mines and torpedoes,
and they possess a superiority over us in these particular directions.
Germany's forward submarine base was on the island of Heligoland.
The U-boats were ordered to sweep the North Sea.
But the British had gone.
On 16th December 1914, hoping to lure the British out,
five German warships steamed across the North Sea.
At seven in the morning, they opened fire on Scarborough and Hartlepool.
There was a terrific crash, we thought it must be thunder.
When another crash came, we rushed to the window and saw smoke
and cried "It's the Germans!"
Two wee girls hung on to me and said "Are the Germans going to kill us?"
122 people died in the attack.
It was the first time enemy warships
had killed anyone on the British mainland in over a century.
Jellicoe, too, had thought about attacking the enemy's homeland,
not with a hit-and-miss naval bombardment,
but a blockade, tight as a drum, and lethal.
What we have to do is starve and cripple Germany.
The destruction of the German fleet is a means to an end,
and not an end in itself.
Here was a use for those huge battleships,
as sentinels sealing the exits from the North Sea,
stopping Germany's fleet getting out and food and war supplies getting in.
The North Sea would become no-man's-land - a dead sea.
Jellicoe was helped by an invention
more important than Dreadnoughts or even submarines - wireless.
MORSE-CODE SIGNAL
Every day, every German ship radioed its position
back to fleet headquarters at Wilhelmshaven.
MORSE CODE SIGNAL CONTINUES
Over the North Sea, in the coastguard station at Hunstanton, Norfolk,
British Naval Intelligence was listening.
The German messages were passed on to code breakers
in one of Britain's most secret departments -
Room 40, deep in the heart of the Admiralty Old Building.
According to one of their officers, the men in Room 40 were a mixed bag.
They knew literary German fluently and they could be relied on,
but of cryptography, of naval German,
of the habits of war vessels of any nationality, they knew not a jot.
Some, like Dillwyn Knox,
would help crack the German Enigma code in the Second World War.
But in 1914, they desperately needed some clues.
The break came in the Baltic Sea,
where a German cruiser, the Magdeburg, was captured by Russians.
On board, they found one of the war's most valuable documents
and passed it on to their British allies.
This is the Magdeburg's code book.
It allowed the men in Room 40
to read nearly everything the German navy was planning.
"Oh, well," the Kaiser said, on learning of the Magdeburg's capture,
"sparks are bound to fly at a time like this."
But the Kaiser had no idea his enemies had his code book,
no idea of the immense advantage they now possessed.
Britain's sea strategy in the First World War was simple -
to isolate and starve her enemies.
At Scapa Flow and Rosyth to the north,
at Dover and Harwich to the south,
the Royal Navy closed the North Sea to German ships.
The blockade was a brutal vision,
brainchild of Maurice Hankey of the Committee of Imperial Defence.
My belief in sea power amounted almost to a religion.
The Germans, like Napoleon, might overrun the Continent.
This might prolong the war,
but the final issue would be decided by economic pressure.
The Director of Naval Intelligence agreed.
Grass would sooner or later grow in the streets of Hamburg
and widespread death and ruin would soon be inflicted.
Germany began the war with a merchant fleet of nearly four million tons.
Within months, she lost a quarter of her ships,
seized in harbours or caught making a dash
into the no-man's-land of the North Sea.
Lloyd's of London kept a log of every vessel sunk.
Their records show that on one day alone, 8th August 1914,
Germany lost 41 ships.
Neutral countries - Holland, Denmark, Sweden - were not spared.
Germany depended on ports like Rotterdam for grain and raw materials
so Britain forced neutral ships to submit to the blockade.
Starting with Holland, the British pressured companies to declare goods.
In every country, she built up a network of agents.
They tracked ships coming and going, who was sending what, where.
Any ship could be stopped.
Any found with banned supplies for Germany had its cargo seized.
Within weeks, the German government started to ration food.
Caroline Ethel Cooper was an Australian stranded in Leipzig.
Every week, she wrote to her sister in Adelaide.
Dear Emmie, the government's seized the bread, flour and meal supply.
We're allowed four pounds of bread and one pound of flour at a time.
Now the war against neutral ships and food supply has begun,
prices rise every week.
Sailors like Richard Stumpf were stuck in harbour,
frustrated and hungry.
2nd April 1916.
We spend our time worrying about our bellies.
Even the officers are embittered and dissatisfied.
To end Germany's isolation, her navy came up with a revolutionary plan -
an unarmed submarine over 200 feet long,
that could carry a cargo of 1,000 tons.
In June 1916, the Deutschland set out for America,
the first time a submarine had tried to cross the Atlantic.
Because of wet weather and high seas,
the hatches were closed
and diesel engines pumped hot, humid air through the boat.
Sweat ran down the bulkheads and water leaked around loose rivets.
Drinking water tasted like diesel
and every meal the cook cooked had a layer of oil across the top.
Approaching the American coast,
Captain Koenig ordered us to say nothing of the strain we'd undergone
and to avoid mentioning our seasickness.
Now, after two world wars, it's taken for granted
that America and Britain are close allies, naturally on the same side...
..but in the First World War, it wasn't so clear.
Eight million Americans had German parents or grandparents.
Four and a half million were of Irish descent.
Many of them had little love for England.
At the outbreak of war,
thousands of US citizens had tried to enlist in the German army...
..and America was enjoying a massive economic boom.
Half Britain's war budget was spent in the States.
Companies like Bethlehem Steel were swamped with orders.
They hauled in six times the profits they'd made before the war.
The Deutschland was just another good customer.
Her brave Atlantic crossing, dodging Royal Navy warships,
was a rallying point for anyone who'd suffered from the British blockade.
Our crossing became a triumph.
All the neutral steamers, American or not, greeted us with sirens.
Only an English steamer sailed past in deadly silence,
while we were proudly raising the black, white and red flag.
The Deutschland's crew received a hero's welcome.
There were dinners in their honour, Captain Koenig met the President.
The three weeks spent in the United States were a non-stop party.
Everywhere we went, people gathered round us,
they all wanted a souvenir of some kind.
I sold the buttons off my shirt and the stripes off my tunic.
Germans introduced their daughters and we never had to pay for beer.
The Deutschland returned to Germany with vital nickel and rubber.
The help to the economy was nothing compared with the boost to morale,
as even Caroline Ethel Cooper had to admit.
The town is flagged because the Deutschland got safely back.
Those red, white and black flags always makes me sick,
but I'm glad she got across all the same. It was a sporting run.
But the Deutschland was too small to break the blockade.
In Germany and Austria, there were not enough people to work the land
and too many officials trying to ration what food there was.
The situation with the hunger and queues is turning nasty.
People wait for potatoes in their hundreds, four deep,
from four in the morning until the afternoon.
Every morning, there are queues of armchairs and cushions,
upon which people sit and sleep.
The shortages worsened after the terrible harvest of 1916.
Germans called it the Turnip Winter.
Many had nothing to eat but cattle fodder.
There were 50 food riots that year.
Oh, what days of terror, everything's in turmoil!
There was havoc in town last night.
The window panes were smashed in at Cafe Kaiserhof.
Angry crowds were shouting outside bakeries and inns.
Up at the castle, they cursed the major in words I shan't repeat.
The army appeared at 11.
It's horribly cold
and because the rolling stock has all been taken for the war effort,
there is an extreme shortage of coal.
We are learning how to be freezing
which isn't the most pleasant feeling.
Schools, theatres and cinemas have all been closed until further notice
because of the lack of coal.
The German navy did nothing to help.
Even if large parts of our battle fleet lay at the bottom of the sea,
it would accomplish more than now, lying well-preserved in our ports.
At Wilhelmshaven, people wrote graffiti on the walls.
Dear Fatherland, you may rest assured.
The fleet's in harbour, safely moored.
Admiral Reinhard Scheer had been ordered
not to risk his ships against the full British fleet,
but by mid-1916, the pressure to do something was intense.
On 31st May, Germany's High Seas Fleet steamed out of Wilhelmshaven,
hoping to engage the Royal Navy's battle cruisers.
But the British were one jump ahead.
MORSE-CODE SIGNAL
The men in Room 40 had already decoded Scheer's orders.
Three hours before the Germans even left harbour,
the entire British Grand Fleet was on its way to intercept them.
Now, the world would get the great sea battle it had waited for -
Jutland.
It was a titanic clash - 250 warships, 100,000 men.
Britain's first great fleet action since Trafalgar.
It was a fight they had to win.
If Germany ended up masters of the North Sea,
the blockade would be finished, the British Army in Europe cut off,
Britain open to invasion.
Admiral John Jellicoe was, Winston Churchill said,
the only man who could lose the war in an afternoon.
Less well-armoured than Germany's
Britain's ships preferred to fight at very long range,
but at Jutland, the range was just five miles.
We fired very slowly with deliberation,
while the Kaiser-class ships in front of us shot like mad.
Now, the English were in an unfavourable position.
A shot hit the bridge of a German destroyer and blew it to hell.
Shells fell all around us, and what with ships sinking and dying bodies,
it made one shiver at the sight of it.
At 4.30pm, the battle cruiser Queen Mary was hit by a shell
which exploded in the ship's magazine.
A horrible sight, it was.
An enormous height of red flame,
followed by a mass of black smoke
amongst which was the wreckage, thrown in all directions.
The blast was tremendous!
Admiral Beatty watched from HMS Lion.
There seems to be something wrong with our bloody ships today!
About seven o'clock we passed the wreck of a large ship,
which we hoped was a German but later learned was one of ours.
She was broken right in two,
the bow and stern was sticking up about 50 feet and quite independent.
But the British had the Germans outgunned and outnumbered.
As evening fell, the German fleet broke off the action.
We were in a regular deathtrap.
The only way to escape the unfavourable tactical situation
was to turn about and withdraw on the opposite course
and get out of this dangerous enemy envelopment.
To "Silent Jack" Jellicoe, peering through the fog of battle,
it looked as though the Germans were lulling the British into a trap.
If the enemy battle fleet turned away from an advancing fleet,
I should assume the intention was to lead us over mines and submarines.
So Jellicoe ordered the British to turn, as well,
away from their vulnerable foe.
As night fell on 31st May 1916,
the men in Room 40 tracked the retreating German fleet.
They passed its positions to the Navy,
giving Jellicoe a last chance to finish the Germans off.
But the Navy failed to catch them and the German fleet made it home.
During the night, telegrams gave estimated losses of the English
as two to three in our favour.
The Kaiser announced at breakfast,
"We have won a great victory in the North Sea!"
Based on the maths alone, the Kaiser was right.
Germany had lost 11 ships and 2,500 men,
Britain, 14 ships and 6,000 men.
But that wasn't the point.
The Kaiser's battleships stayed in harbour until the end of the war.
The British fleet still ruled the North Sea, tightening the blockade.
Germany had replied to the British blockade with her own economic war.
She, too, tried to cripple the enemy by cutting off supplies.
This light raider, the Mowe,
was one of the few surface ships Germany sent into the North Sea.
Her target - not warships, but cargo boats.
She sunk 20,000 tons, building a large collection of captured crews.
The English say we're in league with the devil
and have acquired the Flying Dutchman.
The captain of the Mowe said,
"What a great moment when I had eight English captains before me
and I could tell them all 'This is the work of the German fleet!'"
Germany's U-boats joined in the war against Allied trade.
One British admiral was horrified.
Submarines are underhand, unfair and damned un-English!
As for U-boats attacking civilian ships,
it is impossible and unthinkable.
If they do, their captured crews should be hanged as pirates.
The U-boat blockade of Britain would have to be ruthless.
Chancellor Bethmann Hollweg realised the effect of this on world opinion,
as he told Georg von Muller.
Spent the afternoon with the Chancellor,
who wished once more to discuss the U-boat question.
Bethmann envisaged the remaining neutrals united against us
as the "mad dog" among the peoples of the world.
That would mean the end of Germany.
Germany's admirals were furious at having their hands tied,
but submarines were ordered to stick to the old rules of war.
They gave warning of their attacks, they did not attack underwater,
they gave merchant crews time to escape.
German submarines sank a quarter of a million tons in 1914,
but Britain built new ships faster than the U-boats could sink them.
Far from being choked by a blockade, the British economy flourished.
The British firm Vickers, with a workforce of 78,000,
turned out guns, aeroplanes, battleships - and record profits.
If Germany was trying to play fair, Britain wasn't.
Q-ships looked like unarmed traders, but carried hidden guns.
They looked like easy prey, but when submarines came close,
the Q-ships uncovered their guns and attacked.
To add to the deception, they often sailed under foreign flags.
Lieutenant Heinrich Crompton, on the U41, was caught by just such a trick.
As the two ships came within 300m of each other,
the steamer opened a heavy accurate fire from along the railing,
immediately joined by large-calibre guns, hidden fore and aft.
The U41 returned three rounds from a forward gun, all hits to the hull.
Throughout the action, the steamer continued to fly the American flag.
On 1st February 1915,
in response to the British blockade, the Kaiser stepped up his campaign.
He declared all waters around Britain a war zone,
in which any ships, including neutrals, might be sunk.
This decision set Germany on a collision course with America.
The pride of the Cunard line, the Lusitania,
was the world's largest, most luxurious liner.
She could carry over 2,000 passengers.
HORN BLARES
There was a ragtime dance written in her honour.
LIVELY TWO STEP MUSIC PLAYS
On 1st May 1915,
Cunard posted a list of her departures in the New York Times.
Next to it was an advertisement placed by the German ambassador.
Those sailing to Britain, it said, did so at their own risk.
At 11.30 that morning,
the Lusitania left New York for Liverpool.
Her captain made light of the submarine threat.
It's the best joke I've heard,
this talk of torpedoing the Lusitania!
This is the last picture of her ever taken.
The Lusitania sighted the Irish coast on 7th May.
The lighthouse on the Old Head of Kinsale,
was traditionally used by ships on the Atlantic run
to get their bearings.
At 2:10, the Lusitania was hit by a single torpedo.
As I watched, one funnel went, then the other, then the other,
until the ship had gone and the sea was calm,
and all you could see was bodies and wreckage of furniture,
and everything that had been in the ship, floating in the water.
My husband and I got in a lifeboat, the ropes of which had to be cut,
since when I have not seen or heard of my husband.
I've lost all I ever possessed
and my dead boys, ages 11 years and eight.
I was rescued by a trawler.
My dear husband was lost, but I had the satisfaction of finding him
and seeing him laid to rest in the cemetery in Queenstown.
Police reports were sent to relatives to identify the bodies.
1,200 people died on the Lusitania, including 128 Americans.
At the battle fronts in Europe, tens of thousands were dying every day,
but the fate of the Cunard liner overshadowed them.
It led to the most widespread anti-German riots of the war.
In Liverpool, an American joined the mob outside a German-owned shop.
The crowd was growling and the shop was dark,
but there were people upstairs.
I picked up a brick and heaved it through a window.
Then everyone took to shying them and in a few minutes,
the place was a wreck.
There were several policemen at the corner and they just grinned.
With the sinking of the Lusitania, Germany had crossed a line.
The world hates us as we are conducting a war in a brutal manner,
and the brutality is increasing.
I was at a party when a report of the Lusitania arrived.
Two officers' wives, mad with joy, started to dance about the room.
"Don't forget," I said, "there were women and children aboard."
"That doesn't matter," they said, and danced on.
"The more who go to the bottom, the better."
The Lusitania came to stand for German barbarity.
Britain stirred the indignation with propaganda -
posters and even posed photographs rammed home what had happened.
The German embassy in Washington received bomb threats.
President Wilson began to see Germany as the "mad dog of the world".
In God's name, how could any nation calling itself civilised
do so horrible a thing?
It seemed America might clamber down off the fence.
But outrage soon gave way to caution.
Wilson reassured the nation that America would not go to war.
There is such a thing as a man being too proud to fight.
There is such a thing as a nation being so right
that it does not need to convince others by force that it is right.
And anyway, war would be very bad for business.
Wilson kept the United States prepared but neutral for two more years.
The sinking of the Lusitania was terrible,
but it was not reason enough to throw away more lives, and profits,
by joining in a distant war.
Germany's policy in America after sinking the Lusitania was complex.
She kept her U-boats in check, but not her spies.
In 1916, German agents blew up Black Tom Island,
a loading depot in New York harbour.
It held 900 tons of ammunition destined for the Allies.
Several thousand persons lined the sea wall and acquired a real picture
of what the firing line in the European war looks like.
The water line was one mass of red glare.
The explosions were so strong,
they were felt in Philadelphia, 90 miles away.
German agents slipped bombs onto ships in US ports.
There were assassination attempts
and even a bomb planted in the US Capitol.
German agents are everywhere.
Extraordinary precautions are now necessary
in the arms factories, at the docks and on board vessels,
even vessels of the United States Navy.
Hard evidence tying Germany to espionage against America
came from one of the spies himself.
Heinrich Albert left his briefcase on New York's elevated railway.
It held documents proving the German embassy was bankrolling the sabotage.
Two diplomats, including Franz von Papen,
Hitler's future vice-chancellor, were expelled.
But nothing got in the way of business on the New York stock exchange.
When Germany won a battle, Allied stocks fell.
When Britain won, her shares rose.
American investors were betting on the war.
For Cabinet minister David Lloyd George,
there was a direct connection between battle and bank.
Success means credit.
Financiers never hesitate to lend to a prosperous concern.
France and Russia paid for the war by borrowing from Britain.
Britain raised money on the American stock market
through her Wall Street bankers, JP Morgan.
It was spent buying American armaments, American supplies.
Of all the money raised in America to pay for the war,
99% went to Britain and the Allies.
It was something that made Germans wonder
just how neutral America really was.
30th January 1916.
In financial circles, it is said England has won the war already
and every day it goes on after March makes the ruin of Germany completer,
no matter what her military successes may be.
America lent so much that by the end of 1916,
the central bank warned that people were betting too heavily on Britain.
If the Allies lost, they might never get their money back.
The thought that American cash might be backing the wrong side
wiped a billion dollars off Allied stocks in a week.
Germany's generals felt the odds were stacking up against them.
They grew impatient at hesitant politicians tying their hands.
In view of the military situation,
we must lose no time in adopting the measure
of torpedoing armed enemy merchantmen without notice.
The Entente continue the war with all the resources at their disposal.
Our ambassador prophesies war with America
if we persist in torpedoing armed merchantmen without warning.
The Kaiser wrote in the margin of the report "I do not care!"
The Kaiser didn't care because of some key German calculations.
His generals gambled that if America joined the Allies,
she would not have a decisive impact on the fighting in Europe until 1919.
Long before then,
the U-boat campaign would bring Britain and France to their knees.
One thing stayed Germany's hand.
In December 1916, she put out a peace feeler to the Allies,
believing she could hold on to her gains.
The French and British leaders met in Paris and rejected the offer.
Germany now staked everything on a new submarine campaign.
U-boats would sink all ships on sight, without warning.
February 2nd is a special and uplifting day for us Germans,
the beginning of the all-out submarine war.
We're holding our breaths and hoping with this radical medicine,
we will finally cure England of her arrogance and secure a quick peace,
the terms of which we will dictate.
In April 1917, Germany sunk over 800,000 tons,
causing panic at the British Admiralty.
But Germany didn't have enough U-boats to sustain the success,
and Allied ships were getting better at protecting themselves.
Merchant ships now travelled not singly, but in convoy,
with more destroyers to protect them.
Airships and aeroplanes scouted overhead,
looking for the telltale signs of submarines.
63 U-boats were sunk in 1917 -
three times the losses of the previous year.
One captured U-boat was put on display in London.
13,000 people paid to view it on the first day.
Its German sailors couldn't believe the contrast
between the Allied home front and their own.
We remained in Dover for two and a half days
and were plentifully supplied with food, drink and smokes,
for you notice nothing of the war.
There are no wooden soles or bicycles with wooden tyres
and the butchers' shops have rows and rows of pigs hanging up.
There is no prospect of starving England.
I am glad, for the war is over for me.
The second U-boat campaign was a double failure.
It didn't deliver militarily -
German submarines could not sink enough Allied ships -
and it was a diplomatic disaster, pushing America to the brink of war.
The final shove came from the men in Room 40.
On 16th January 1917,
Britain intercepted a telegram from German Foreign Secretary Zimmerman
to his ambassador in Mexico City.
The Zimmerman telegram was made up of a thousand numerical code groups.
It took two weeks to decipher.
As the meaning emerged, the men in Room 40 realised
they held the most extraordinary intelligence of the war.
Destined for the Mexican Government,
it outlined Germany's plan for Mexico to invade the United States.
We make Mexico a proposal of alliance
with an understanding on our part
that Mexico is to reconquer Texas, New Mexico and Arizona.
The settlement in detail is left to you.
Zimmerman's scheme was harebrained.
Mexico was in the midst of revolution,
US troops were already fighting bandits on the border.
There was no way the Mexican Government wanted more trouble.
But Germany's proposal was a godsend to Britain.
It was just what she needed to end America's neutrality.
Two weeks into the U-boat campaign,
Britain called the US ambassador to the Foreign Office
and passed over the telegram.
It was, said Britain's Foreign Secretary,
"as dramatic a moment as I remember in all my life."
On 2nd April, President Wilson went to the Capitol.
The United States had not declared war when the Lusitania went down,
it had not declared war when spies blew up its shipyards,
but Germany urging Mexico to attack America was in a different league.
On 6th April 1917, the United States declared war against Germany.
For three years, the country had played the war's banker and supplier.
Now, as far as Wilson was concerned,
America was fighting a crusade for international justice and democracy.
The North Sea would remain dead until the very end.
The Germans now set themselves a desperate task -
to win the war before American troops arrived in force.
President Wilson's liberal crusade would be up against new ideas,
of socialism and revolution.
In the next episode of The First World War,
German spies sow rebellion in Ireland and Russia
and French troops mutiny on the Western front -
a war against war itself.