In August 1914, the two greatest navys 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 thirteen and seven building.
Austria-Hungary: three. America: ten.
Britain: twenty.
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 the two sides looked at the map, the more obvious their problems became.
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.
Jacky Fisher, Britain's sharpest admiral, predicted radical change ahead:
The use of submarines has convinced us that in wartime nothing can stand against them.
The submarine is the coming type of war vessel for sea fighting.
It means that the whole foundation of our traditional 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, U-21, made her way to the Firth of Forth,
where the British cruiser, HMS Pathfinder, was leaving Rosyth naval base.
U-21 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 U-9.
Through my primatic glasses I noticed a small masthead coming into view,
near the Maas Lightship.
It looked like the mast of a warship.
Could this be the first sight of the enemy that we were to have during the war?
The U-9 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 500 metres.
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,
and the whole ship shook and all the crockery in the pantry fell.
Then Cressy and Hogue arrived and let down their boats.
The Aboukir went down suddenly 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 just going on board,
when she was struck and sank in three minutes.
I then swam on to the Cressy and was hauld up the side with a rope.
But she was struck also and we sank.
George 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 U-9 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 young 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 has happened is exactly what we predicted,
ships stand by 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.
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,
at the very limits of the U-boats' range.
He warned the Admiralty:
The Germans have shown that they rely to a very great extent
on submarines, mines and torpedoes,
and there can be no doubt that they possess an actual 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 the 16th of 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 sudden thunder.
But when another crash came, we rushed to the window
and saw a lot of smoke and cried, "It 's the Germans!"
Two of the 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 been thinking about attacking the enemy's homeland,
but his weapon would not be 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 her vital 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.
Every day, every German ship radioed its position
back to Fleet headquarters at Wilhelmshaven.
Across the North Sea, in the coastguard station at Hunstanton in Norfolk,
British Naval Intelligence was listening.
The German messages were passed on to a group of code breakers
working 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 ordinary 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 the Russians.
On board, they found one of the most valuable documents of the war
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 could not affect the final issue,
which 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.
Lloyds of London kept a log of every vessel sunk.
Their records show that on one day alone, the 8th of 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 shipping companies into declaring their 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 since the start of the war.
Every week, she wrote to her sister in Adelaide.
My Dear Emmie, the Government has seized the whole bread flour and meal supply of the country.
We are allowed only four pounds of bread and can only buy one pound of white flour at a time.
Now that 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 of April 1916.
We spend most of 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 ever tried to cross the Atlantic.
Because of the wet weather and the high running seas,
the deck hatches were closed most of the time,
and the diesel engines pumped hot humid air throughout the boat.
Sweat ran down the bulkheads and water leaked around loose rivets.
The drinking water tasted like diesel,
and every meal the cook cooked had a layer of oil across the top.
As we approached the American coast,
Captain König ordered the crew to say nothing to anyone,
about the strains we'd undergone during the trip,
and to especially avoid mentioning our seasickness.
Now, after two world wars,
it's taken for granted that America and Britain are the closest of 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 had made before the war.
The Deutschland was just another good customer.
Her brave Atlantic crossing, dodging Royal Navy warships,
became a rallying point for anyone who had suffered from the British blockade.
Our crossing gradually became a triumph.
All the neutral steamers we met, American or others,
greeted us with three hoots or with their sirens.
Only an English steamer sailed past in deadly silence,
while we were proudly raising the black, white and red flag in the wind.
The Deutschland's crew received a hero's welcome.
There were dinners in their honour.
Captain König was invited to meet the President.
The three weeks we 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 even sold the buttons off my shirt and the stripes off my tunic.
German families introduced us to their daughters and we never had to pay for beer.
The Deutschland returned to Germany with a vital cargo of nickel and rubber.
The help it gave the economy was nothing compared with the boost to German morale,
as even Caroline Ethel Cooper had to admit.
The town is flagged today because the Deutschland has got safely back.
The sight of those red white and black flags always makes me sick,
but I am 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, lined with armchairs and cushions,
upon which people sit and sleep.
The shortages worsened after the terrible harvest of 1916.
The Germans called it the Turnip Winter.
Many had nothing to eat but cattle fodder.
There were fifty food riots that year.
Oh, what days of terror! Everything's in turmoil!
There was havoc in town last night.
The windowpanes were smashed in at Café Kaierhof.
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 eleven.
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're learning how to be freezing, which isn't the most pleasant feeling.
School, 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 were lying at the bottom of the sea,
it would have accomplished more than it does 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 Reinhardt 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 the 31st of 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.
The men in Room 40 had already decoded Scheer's orders.
Three hours before the Germans had 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 been waiting 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 herself 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.
Our first 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 and dead bodies floating about, it made one shiver at the sight of it.
At 4:30 p.m., the battle cruiser Queen Mary was hit by a shell,
which exploded in the ship's magazine.
A horrible sight it was.
First an enormous height of dull red flame, followed by a great 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 at that time we hoped was a German but later learned was one of ours.
She was broken right in two.
The bow and stern were sticking up about fifty feet and quite independent.
But the British had the Germans out-gunned and outnumbered.
As evening fell, the German Fleet broke off the action.
We were in a regular deathtrap.
There was only one way to escape the unfavourable tactical situation,
turn the line about and withdraw on the opposite course.
We had to get out of this dangerous enemy envelopment.
To "Silent Jack" Jellicoe, peering through the fog of battle,
it didn't look as though the Germans were running for home,
but lulling the British into a trap.
If the enemy battle fleet were to turn away from an advancing fleet,
I should assume that 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 the 31st of May 1916,
the men in Room 40 tracked the retreating German Fleet.
They passed its positions on to the Royal Navy,
giving Jellicoe a last chance to finish the Germans off.
But the Royal Navy failed to catch them and the German Fleet made it home.
During the night, telegrams arrived giving the estimated losses of the English,
which are 2 to 3 in our favour.
The Kaiser was therefore able to announce at breakfast,
"We have won a great victory in the North Sea."
Based on the maths alone, the Kaiser was right.
Germany had 11 lost ships and 2.500 men.
Britain: 14 ships and 6.000 men.
But that wasn't the point.
The Kaiser's battleships were back in harbour, and stayed there till the end of the war.
The British Fleet still ruled the North Sea, evermore tightening the blockade.
From the start, 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 Möwe,
was one of the few surface ships Germany ever sent into the North Sea.
Her target not warships, but cargo boats.
She sunk 20.000 tons, building a large collection of captured crews.
According to the English we are in league with the devil
and have acquired the Flying Dutchman.
The captain of the Möwe said recently, "You can imagine what a great moment it was,
when I had eight English captains standing in front of 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.
But Germany's chancellor, Bethmann-Hollweg,
realised the effect this would have 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 warnings of their attacks.
They did not attack underwater.
They gave merchant crews time to escape.
German submarines sunk 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 the German 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 U-41 was caught by just such a trick.
As the two ships came within 300 metres of each other,
the steamer opened a heavy accurate rifle fire from all along the railing,
immediately joined by large-calibre guns hidden fore and aft.
The U-41 immediately returned three rounds from the forward gun, all hits to the hull.
Throughout the action the steamer continued to fly the American flag.
On the 1st of February 1915, in response to the British blockade, the Kaiser stepped up his campaign.
He declared that all the waters around Britain were 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 largest, most luxurious liner in the world.
She could carry over two thousand passengers.
There was a ragtime dance written in her honour.
On the 1st of 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 in many days, this talk of torpedoing the Lusitania.
This is the last picture of her ever taken.
The Lusitania sighted the Irish coast on the 7th of 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 into a lifeboat,
the ropes of which jammed and 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 eleven years and eight.
I was rescued by a trawler.
My dear husband was lost but I had the great satifaction of finding him on Saturday,
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 great Cunard liner overshadowed them.
It led to the most widespread anti-German riots of the war.
In Liverpool, a newly-arrived American joined the mob outside a German-owned shop.
The crowd was muttering and growling, and the shop was dark,
but there were people upstairs.
So I just picked up a brick and heaved it through the 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 whole world hates us because we are conducting the war in such a brutal manner.
And the brutality is increasing.
I was at a party when the report of the torpedoing of the Lusitania arrived.
I saw two officers' wives who, mad with joy, started to dance about the room.
"Don't forget", I said, "that there were also 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 its own propaganda.
Posters and even posed photographs rammed home what had happened.
The German Embassy in Washington received bomb threats.
President Woodrow Wilson himself began to see Germany as the "mad dog of the world."
In God's name, how could any nation calling itself civilized 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 that didn't seem 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 waterline 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 American ports.
There were several assassination attempts, and even a bomb planted in the US Capitol.
German agents are everywhere.
Extraordinary measures of precaution have now become necessary in all the arms factories,
at the docks and on board vessels, even vessels of the United States Navy.
Hard evidence tying Germany to espionage operations 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 senior 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 British 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 in turn 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 many Germans wonder just how neutral America really was.
30th of January 1916.
In financial circles it is openly said that England has won the war already,
and every day that it goes on after March, can only make 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 mere 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 are continuing the war with all the resources at their disposal.
Our ambassador prophesies war with America if we persit in our intention
of 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 have brought 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 the 2nd is a special and uplifting day for us Germans,
the beginning of the all out submarine war.
We're all holding our breaths and hoping that 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 lying in wait.
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 we were plentifully supplied with food, drink and smokes,
for you notice nothing of the war here.
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 to make a difference.
And it was a diplomatic disaster, pushing America to the very brink of war.
The final shove came from the men in Room 40.
On the 16th of January 1917,
Britain intercepted a coded telegram from German Foreign Secretary Zimmerman
to his ambassador in Mexico City.
The Zimmerman telegram was made up of 1.000 numerical code groups.
It took two weeks to decypher.
And as the meaning emerged,
the men in Room 40 realised they were holding the most extraordinary intelligence of the war.
Destined for the Mexican Government,
the telegram 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 middle of a 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 Zimmerman telegram.
It was, said Britain's Foreign Secretary,
"as dramatic a moment as I remember in all my life."
On the 2nd of 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 the 6th of 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 president 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.
And 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 so rebellion in Ireland and Russia.
And French Troops mutiny on the Western Front.
A war against war itself.