Original subtitles

MAN: Fire.

ROBERTS: Donitz' fleet is expanding,

and he will not rest until he's sent every convoy ship

to the bottom of the North Atlantic.

DONITZ: Heil Hitler.

ROBERTS: Donitz has 300 U-boats. Monster wolfpacks.

- We need more ships.

CHURCHILL: You admirals are always asking for more and more ships

and, when you get them, things get no better.

DONITZ: This is war, not a bloody board game.

LAIDLAW: We have designed these tactics as tools

which will save you time when you are at sea.

Seconds that can save lives.

DONITZ: I want this convoy wiped out, Gott.

Destroyed.

LAIDLAW: What if...

What if we don't prevail out there?

DONITZ: I need results, Gott.

LAIDLAW: And ladies, remember,

the work we are doing here is more important than ever.

Never forget that.

DONITZ: If there's going to be an unconditional surrender,

it will be theirs not ours.

- (Morse code beeping)

NARRATOR: Admiral Karl Donitz,

head of the U-boat fleet and rising star of the nazi party,

has been summoned by Hitler.

- (phone rings)

TOEPPEL: Donitz was a dedicated nazi.

He was with the nazi cause.

He believed in the Fuhrer,

he loved the Fuhrer, he admired the Fuhrer.

He said, "The Fuhrer is a genius."

- (Donitz clears throat)

Heil Hitler!

NARRATOR: After failing to stop the convoys using surface ships,

the head of the German Navy has resigned.

RICHIE: And Donitz is waiting in the wings

to take his place.

He's absolutely thrilled.

- I won't let you down.

RICHIE: Because having nursed these ideas and ambitions

of winning the Atlantic War with U-boats,

he's all of a sudden in control.

And so, from January 1943,

he feels that he's invincible and unstoppable.

NARRATOR: At WATU,

the Western Approaches Tactical Unit,

Captain Gilbert Roberts and Wren Jean Laidlaw

are tasked with devising anti-U-boat tactics.

RICHIE: Churchill always said

that one of the things that he most feared in the war

was the Atlantic War, was the U-boat War.

Roberts and Laidlaw at WATU

feel this pressure enormously.

ROBERTS: Ladies,

I'm not gonna sugar-coat this. We need food supplies.

Donitz' fleet is expanding,

and he will not rest until he's sent every convoy ship

to the bottom of the North Atlantic.

And ladies, remember, the work we are doing here

is more important than ever

and every one of you plays an essential part.

Never forget that.

All of us, it's our job to prove that these tactics work.

To teach these officers... ROBERTS: Ah!

You two, here. LAIDLAW: Good morning gentlemen.

NARRATOR: Officers attending the WATU war gaming courses

learn the tactics they will use at sea.

RICHIE: WATU now starts to give these courses to many, many people.

They run from Monday til Saturday every single week,

day in day out,

from February 1942 until the end of the war.

LAIDLAW: Below you is the North Atlantic.

Each line marks a mile.

The U-boats will be invisible to you,

as they would be in normal conditions at sea.

If you could take your places behind the screens please?

You have two minutes for your first move.

Be decisive.

Communicate effectively.

Go.

STRONG: War gaming has been used for centuries

to test how armies might operate in a future war.

It is the only way to explore

how an enemy might think

without actually fighting a battle with them.

New German reactions were explored,

they were then introduced into the training process,

so that in the battle space, in the Atlantic,

when an order was given, everybody knew what to do.

This is not a game, this is training for war.

LAIDLAW: Time.

NARRATOR: What scarce food supplies

do get past the U-boats in the North Atlantic

are spread thinly

around the British Isles and Soviet territories.

ROBERTS: Good morning. - Morning sir.

LAWRENCE: Rationing hit Britain incredibly hard.

In 1943, you were allowed 4 ounces of bacon a week,

2 ounces of butter. This is a very small allowance.

One egg, one fresh egg a week.

LAIDLAW: One sausage, one slice of toast.

ROBERTS: One egg, one slice of toast.

Together they make quite a decent breakfast.

LAIDLAW: And we're the lucky ones. - True. True.

I see the queues.

- Mothers having to say "no" all the time.

Are you not going to eat that, Gilbert?

- I don't seem to want it.

LAWRENCE: Gilbert Roberts was cast out of the Navy

because he had TB, and his health has been an issue for him

all through the war.

To the point where, by the time 1943,

his weight was down to 8 stone

and on a man, that is dangerously underweight.

LAIDLAW: But you have to eat.

ROBERTS: I know I should. I just can't find my appetite.

RICHIE: They realized

that every single day that they don't come up with a solution,

more and more ships are going down.

Ships not only means material,

it also means human lives are being lost.

SYMONDS: One of the victories by Donitz's U-boat wolfpacks

comes in March of 1943.

In mid-Atlantic,

there were nearly 100

Allied surface transports.

What the U-boats might have called a target rich environment.

And Donitz vectored several wolfpacks in their direction

and they had something of a field day.

- Another hit.

ROBERTS: Donitz has 300 U-boats.

Monster wolfpacks.

We have nowhere near enough escorts to match that.

NARRATOR: But Roberts and Horton will not be out-gamed.

The Wrens are set the task

of war-gaming the battle in real time.

They add extra naval support ships

to assess how many merchant vessels could be saved.

- Wren? What's the tonnage lost so far?

What are you waiting for? Find out.

LAWRENCE: These two convoys, travelling in tandem,

lost 22 ships to U-boat attack.

That's over 300 lives.

All of these men struggling desperately

to get out of the boats before they slip underwater.

These boats go down in seconds.

Not only was it a devastating loss to the war effort,

but it was a tragic end to so many seamen's lives.

HORTON: If we had those support ships,

we could have saved eight ships,

as I've been telling the Admiralty for months.

I can't wait for them to make up their bloody minds.

If you want something done, do it yourself.

I'm gonna tell Churchill myself.

- There are times...

...when I wonder "Is this how it's going to be for us?"

Losses, defeats.

WREN: Don't think like that. Give it time.

We'll show them.

LAIDLAW: We will.

But there must be times when you think, "what if?"

What if we don't prevail out there?

WREN: Of course.

Everyone thinks about that from time to time, but...

...we have to fight those thoughts.

LAIDLAW: Believe me, I do.

The dark nights of the soul and all that.

"Blood, toil and sweat" as Churchill said.

- And he also said, "We must..." TOGETHER: "..never surrender."

OWTRAM: We certainly realized that this was a serious war.

And then Churchill was doing these inspiring broadcasts,

so we had considerable confidence

in how we were going to cope with it.

"We would fight them on the beaches

and fight them on the landing grounds.

Never surrender"

and that's the sort of way we felt, really.

NARRATOR: Despite his elevated rank,

Karl Donitz maintains direct contact

with his U-boat fleet in the North Atlantic.

DUNLOP: He's now the Grand Admiral Donitz,

but first and foremost he's a submariner.

How do you win the war at sea?

You win it under the ocean with your U-boats.

The Sea War IS the war of the U-boats.

It is a massive problem for western approaches.

NARRATOR: Following Donitz's promotion,

Rear Admiral Eberhard Gott is now Head of U-boat Operations.

- This isn't Stalingrad.

This isn't North Africa.

In the North Atlantic we win our battles.

- 100 U-boats here,

stalking the Black Pit.

100 being repaired.

100 ready to be deployed.

They don't stand a chance.

They think they're going to invade France.

How?

How will they get their troops across.

DONITZ: The Sea War is the U-boat War.

If there's going to be an unconditional surrender,

it will be theirs, not ours.

TOEPPEL: March 1943

really was a very successful month for the U-boat force,

and it looked like if it's really going on like that every month

then maybe we really have the chance

to bring Britain to her knees.

NARRATOR: Following the loss

of over 300 lives in the March battles,

Admiral Horton is determined to increase his fleet.

CHURCHILL: Horton? - Prime Minister.

CHURCHILL: Drink?

- No thank you.

Prime Minister,

we war-gamed a scenario with two convoys in March.

We added three groups of support ships,

rapid response units that...

LAWRENCE: Horton has an ace up his sleeve,

and he can prove that the ships will make a difference,

because he has the strategy.

He has the war game that proves extra ships

can turn the war around for Britain.

- 22 ships were lost in that battle.

If we'd had the extra support ships,

as I've been proposing to the Admiralty for months,

we could have saved eight ships.

Eight ships.

Give me 15 destroyers

and we WILL beat the subs at their own game.

- You admirals!

You admirals are always asking for more and more ships

and when you get them, things get no better.

NARRATOR: But the war game does convince Churchill.

By the end of the month,

Horton is granted his extra 15 warships,

which he forms into five rapid response units.

Amongst them is the destroyer HMS Oribi.

In April 1943,

it arrives in Belfast for repairs.

A young Wren is watching from the plotting room

in Belfast Castle that day.

LAMB: HMS Oribi came in one day

because she'd been so damaged during the storm.

The first thing they did was to send a message to say,

"Send us half a dozen Wrens down to have a drink."

So, half a dozen of us went down to the Oribi to have a drink.

That's how it all began.

NARRATOR: The 22-year-old Christian

is about to meet someone who will change her live forever,

and involve her in one of the most ferocious battles

of the North Atlantic.

- Another three depth charges.

He'd already used every single depth charge on his ship.

Where did he think he was getting another three from?

(sighs)

Thankfully, they can make their mistakes here

and not at sea. - Hmm.

Could I ask you something?

Do you think, I mean...

...should I talk more slowly? Or more quietly?

I just tend to boom somewhat, wouldn't you say?

- At times, perhaps.

STRONG: In Roberts' early lectures,

it was remarked upon that some of his speeches

were garbled or unclear.

His solution is brilliant.

He goes to Liverpool Theatre where Tommy Handley is performing.

- Now go on, buzz off. Bait your fishing rod with a sausage

and catch a tittler. - A tittler?

- Yes, an Adolf Tittler. - (laughter)

LAWRENCE: Tommy Handley had a satirical radio show,

which took the mick out of Hitler

which, of course, allowed him to teach Roberts, you know,

these little, you know, references he could put into his talks

to make them more interesting and engaging.

ROBERTS: You know, I would like to get this thing right.

Get the message through. Make them understand

how important it is when they're out there.

LAIDLAW: I think they do understand that.

ROBERTS: You know I like to send them on their way

with a memorable line, give them courage?

I want to know I'm doing it right.

LAIDLAW: The Prime Minister, he's rather fond of pauses.

ROBERTS: Yes? - Hm.

- Very well.

Would you mind listening? - Of course.

(very loud) - The Battle of the Atlantic...

(quieter) The battle for the Atlantic.

STRONG: The WATU course

is teaching communications and coordination.

What it's doing, it's enabling the escorts

to work together more efficiently.

To communicate more clearly

and to trust each other better.

NARRATOR: The escort commander, Peter Gretton,

is a firm believer in the WATU courses.

MILNER: Gretton was an exceptional officer

and clearly one of the bright lights and one of the great escort captains

and anti-submarine captains of the Second World War.

LAIDLAW: If you had used half raspberry,

rather than raspberry,

this would not have happened.

Have I made myself clear?

- Half raspberry. Aye aye sir.

STRONG:An error made in a war game...

- Good. STRONG: ...can often give you

greater insight, than complete success.

If everything runs smoothly, and everything works,

what have you learnt?

- We have designed these tactics

as tools which will save you time when you are at sea.

Time that is crucial.

Seconds that can save lives.

Sir?

The Battle of the Atlantic is unlike any other.

It is the war of the little ships, and the lonely aircraft.

Long, patient, and unpublicised.

Against our two great enemies...

...the U-boat and the cruel sea.

Good luck... and God speed.

SYMONDS: One of the most important convoy battles

of the entire Battle of the Atlantic,

and for that matter of the entire war, was ONS-5.

Donitz decided that he wanted to annihilate this convoy entirely.

To demonstrate to the Allies

that they could not venture onto this ocean.

That that convoy could lose every ship in it.

- So...

ONS-5.

It's one of the largest single convoys ever undertaken.

43 ships bound for Halifax.

On its return it will be carrying

tons of vital food and raw materials.

If you have something to say man, say it to me.

- We will be taking the north route.

Northwest to 61 degrees 45 north,

29 11 west,

east of Ivigtut here

and then southwest along the Great Banks of Newfoundland.

GRETTON: I know, I know. Ice.

It's a risk, yes.

Pack ice more so than bergs.

It can slow us down, damage ships.

But what would you rather have,

ice or more time in the Black Pit?

NARRATOR: The Atlantic Air Gap, known as the Black Pit,

is so far from any air bases,

the convoys travelling through it have no air support.

GRETTON: As you know, we're on our own here.

This is where the wolfpacks prowl.

They'll shadow us, they'll attack at night.

That's their MO.

- There is some good news.

A number of long-range aircraft have been allocated to the convoys,

but the weather is bad out there.

Not even the VLRs can fly in those winds.

- If they could, there's a very small area, here,

even they can't reach. We must have our wits about us.

- The WATU tactics, Raspberry,

Half Raspberry, Artichoke, all of them. Drill them in.

Know them like the back of your hand,

because out there we will need them.

- So, observant...

...what's the formation?

MILNER: He was a pretty hard driver.

He could be quite clipped and quite sharp,

even dealing with a young graduate student

asking him questions.

GRETTON: Why don't you know this?

It should be second nature by now. Sharpen up man!

NARRATOR: At the drinks party on HMS Oribi,

Christian Oldham meets First Lieutenant John Lamb.

CHRISTIAN: One of the things that I liked about him

was his sense of humour, as we find a lot of things funny,

which a lot of people don't find funny.

John and I got engaged after ten days

and, of course, we were only visiting each other part of the day.

It wasn't like ten days in a hotel or something.

It was just enough for us to realize that we liked each other enough.

NARRATOR: The feelings of the newly engaged couple

are about to be tested to their very limit.

On April 22nd, off the coast of Scotland,

ONS-5 assembles.

43 merchant vessels and seven escorts.

In formation, it covers over 81⁄2 miles.

With annihilation as their goal,

Donitz and Gott reconfigure their wolfpacks.

SYMONDS: Donitz laid out the North Atlantic

into a series of squares,

so that he could indicate to the U-boats in the Atlantic

which grid was likely to be target rich.

- I think we move Meise.

Meise has 30... DONITZ: Correct.

We'll reconfigure Meise. It's obvious.

We take 16 boats from here

and we'll form a new patrol line north-south

between latitude 61 degrees 50 and 57 degrees north.

400 miles east of Greenland.

We'll call it Group Star,

and they'll assemble at 0900 hours tomorrow morning.

I want this convoy wiped out, Gott.

Destroyed.

RICHIE: The convoys facing, of course,

the threat of Donitz's U-boats,

this coming right after the mass sinkings in March,

everybody is very fearful that this is going to happen again.

But then the weather turns against them as well

and gale force winds start to hit the ships.

NARRATOR: The day after Christian gets engaged to John Lamb,

HMS Oribi sails out into the North Atlantic

on a secret mission.

CHRISTIAN: The next morning,

after we'd seen the ship sail down the estuary,

to imagine his going out into this dreadful storm,

the ships were in great danger all the time.

It was really the morning after he left

when I realized a feeling of...

...real fear of what you might lose,

which was so dreadful to think of.

NARRATOR: As ONS-5 also heads into the storm,

there is another serious setback.

The news from submarine tracking is bad.

- Expect U-boats in the general area of Newfoundland.

What? - That's a large area sir.

Are there any bearings?

- If I had bearings, Wren, I would give you bearings.

Now get on.

NARRATOR: Code breakers at Bletchley Park

are unable to decipher

the enigma-coded messages from the U-boats.

- What's going on?

Why does this keep happening?

DUNLOP: If Horton knows where the U-boats are,

he can get in contact with the escort commander of ONS-5

and they can avoid the threat.

HORTON: I've got a convoy about to enter the Black Pit.

No air cover, no...

What?

Well, as soon as you know, I need to know.

DUNLOP: But in April 1943,

he doesn't have the intel.

He has no idea where the U-boats are

and that means that the convoy is heading into the unknown.

GRETTON: They're like corks out there without cargo.

We've already had one collision.

CREW MEMBER: Fuel is 62% sir. - Speed?

CREW MEMBER: Four knots.

- I shouldn't have to be dealing with this.

A ship that guzzles fuel.

8% a day! It's a farce.

This is the North Atlantic.

- We'll never be able to fill her with these waves.

We've got a few more days and that's it.

STRONG: HMS Duncan had boiler problems,

so she was using more fuel than usual anyway.

In addition, she was a fast destroyer,

so her fuel use was very high.

NARRATOR: As Gretton heads towards the Black Pit,

the largest wolfpack of the Second World War

begins to assemble.

The captain of U-boat 650 is hunting for prey.

- Masthead spotted!

- Message to U-boat headquarters. Convoy spotted.

Speed eight to ten knots, bearing 2-7-0.

NARRATOR: The message is ciphered on the enigma machine

and radioed to U-boat Command.

SYMONDS: That message would tell Donitz what was coming,

where it was coming, at what speed.

He would then use the grid coordinates

of the North Atlantic

to send his own messages

out to other U-boats in the area,

ordering them to congregate in the appropriate spot,

so that they could all attack the convoy as a wolfpack.

NARRATOR: Spotting a U-boat conning tower,

Gretton calls on his WATU training.

GRETTON: U-boat sighted at a range of about 2 miles, bearing 146.

Expect U-boat contact at any time.

Observant, observant, observant.

ROBERTS: Also known as the square search,

the escort ships conduct a 2-mile sweep

in a square shape around the last known U-boat location.

If the U-boat tries to escape the square,

ASDIC will detect it and the U-boat can be depth charged.

- Convoy, full speed ahead.

Duncan and Tay observant.

STRONG: The escorts that are in the area,

assigned by that tactic,

then search that square in the good knowledge

that a U-boat is probably operating within that area.

DUNLOP: In order to identify where it is,

you need to flush him out with your sonar, your ASDIC.

This is the sound wave that's gonna ping off the shell of the U-boat.

The dreaded sound

that no U-boat captain wants to hear.

- (rhythmic pinging)

STRONG: When they're getting pinged by ASDIC,

they know the British are getting close.

Where they can hear escorts getting closer,

they know their risk is increased.

- Dive.

STRONG: This causes them to go deep, go deeper,

to evade the convoy.

NARRATOR: Once the ships are in the observant formation...

...Gretton launches a pattern of ten depth charges.

- (muffled underwater explosions)

NARRATOR: The convoy doesn't hit any U-boats that day,

but a potentially lethal attack is successfully deterred.

STRONG: If you're a U-boat commander,

you definitely want to avoid

getting trapped by one of these tactics.

As a result, most of the tactics used by WATU,

even if they don't sink a U-boat, will dissuade it from attacking.

WITT: And this was the basic rule in anti-U-boat warfare.

It's not necessary to actually sink a U-boat.

Take away the chance of success

and bring your ship and cargo home. That’s what it’s all about.

TOEPPEL: Even though Donitz was head of the Kriegsmarine now,

when there was an important operation going on,

then he tried to do as much as possible himself.

- 16 boats were supposed to be in position by 0900 hours.

Where are they?

- Yes sir.

Yes sir? Yes sir?

16 boats, sir(?)

Where are they?

- They can't move. The wind-

- Don't whimper to me about bad weather and strong winds

like some little French girl.

Do you want to tell that to the Fuhrer?

This is war, not a bloody board game.

Do your job!

Get the boats there. Now.

Attack.

NARRATOR: Although there is still no intelligence from Bletchley Park,

the on-board technology on HMS Duncan

picks up enemy radio frequencies.

- Bloody magpies chattering.

STRONG: Gretton's use of the term "chattering of magpies"

merely indicates there were multiple signals.

This cascade tells him

that there's a major wolfpack converging on him.

GRETTON: Message to western approaches.

Submarine sighted.

Position, course, and speed

6-1 3-7 north

3-2 4-9 west.

Huff Duff activity suggests several more in the vicinity.

LAWRENCE: It's even worse than they thought.

They're surrounded.

It's a bit like being in a camp at night

in the moonlight and you can hear the wolves howling in the distance.

Gretton immediately messages western approaches

and tells them to send help

and this is the beautiful thing,

Horton, because he's already asked Churchill for his support groups,

is able to send some extra destroyers

to help the convoy.

- Wren?

Message to Oribi.

Detach to support ONS-5.

Position, course, and speed

21-20 hours, 6-1 degrees 3-7 north,

3-2 degrees 4-9 west.

Proceed at 20 knots, weather permitting.

STRONG: If he's wrong,

then that support group has expended fuel

getting to that location

and may not end up fighting any U-boats at all.

If he's correct, they can make a decisive difference to the battle.

It's a vital decision that Horton is making.

NARRATOR: In the mountainous waves,

the Oribi travels slowly.

It will be nearly two days before it reaches the convoy.

Although there had been no direct hits on Donitz's fleet,

two U-boats have returned to base for repairs.

Imbecility.

The magnitude of it.

GOTT: It's gale force ten. The waves-

- You don't get it, do you?

It's this.

What Kretschmer had,

what Prien had

what Schepke had, what I have!

I need results Gott!

Not tomorrow, when the sun shines.

Now.

TOEPPEL: The dark side of Donitz's discipline

was that he demanded a lot from his U-boat crews,

from the commanders, and he put a lot of pressure,

especially when they were not successful.

DUNLOP: We know what the standard U-boat tactic is,

the ideal tactic.

Get in among the convoy shipping lanes

on the surface, late at night, when you can't be spotted.

But the game has changed.

We know we've got the hard weaponry of technology,

we've got the soft,

incredibly ingenious tactics of WATU,

the U-boats are up against it,

and they are being pushed.

The pressure on them is like never before.

U-BOAT CREWMAN: Angle 30 degrees.

Range 2,000.

Torpedo depth five.

RICHIE: They go in between the convoy rows.

- Open bow caps.

RICHIE: Into the fourth row.

CREWMAN: Tube one and two ready.

RICHIE: And they attack point blank.

NARRATOR: The McKeesport,

a merchant ship carrying 68 men,

takes a direct hit.

GRETTON: Convoy, full speed ahead.

Be on the lookout for survivors.

Artichoke. Artichoke.

- (distant explosion)

Artichoke. Artichoke.

LAIDLAW: Operation Artichoke.

To be used when a U-boat attacks by day or by strong moonlight.

The escort astern the convoy

immediately proceeds to the torpedoed ship,

scanning with ASDIC.

All other escorts turn and speed astern the convoy

until 6,000 yards past the stricken ship.

STRONG: The rest of the escorts move to the rear of the convoy

and then basically scan forwards.

The evading U-boat will hopefully run into the line

created by the artichoke tactic.

Again, they are using the fact

that the U-boats are concerned about being hunted.

- (launcher thumping)

CREW MEMBER: Throwing depth charges.

NARRATOR: Once the escort ships are in the artichoke formation,

another pattern of depth charges is dropped.

Again, there are no direct U-boat hits,

but Operation Artichoke deters further attacks.

RICHIE: The McKeesport, there's 68 crew members on board,

and it becomes obvious the ship's just not going to make it.

So the order is given for them to abandon ship.

To leave the vessel to its fate.

GRETTON: Convoy, full steam ahead.

Northern Gem, be on the lookout for survivors.

RICHIE: One of the reasons the Atlantic War

is really so terrible is because of the fact

that human beings are going overboard

and they're going into this terrible icy water.

Sometimes into pools of oil, and sometimes in flames.

You have a life expectancy of only a few minutes.

- Survivors?

- All crew. 68 men, rescued by Northern Gem.

- Good.

Good.

A few years ago we'd have lost them all.

STRONG: What Roberts' war games identify

is that deploying a ship

that should be escorting the convoy to rescue men in the water,

and sometimes women and children,

risks the defence of the convoy itself.

NARRATOR: As a result, in 1942,

designated rescue ships are added to the larger convoys.

STRONG: It means the escorts can concentrate on the job in hand.

Protecting the convoy and hunting the U-boats.

NARRATOR: In Belfast,

Christian Oldham finds herself plotting the course

of her own fiance's ship as it gets closer to the convoy.

LAMB: Well, I really felt rather despairing

and anxious and worrying,

naturally, because it was just an extraordinary experience

to become engaged to somebody

and thereafter, find the whole thing was endangered.

It was something of a nightmare

to be living through this extraordinary situation,

where you had nothing you could do about it,

but just watch from a distance.

RICHIE: The weather is atrocious

and the Oribi, its compass breaks.

It's an absolute disaster.

It finally manages to make it to the convoy

and finds that it's hove to. It's stationary.

NARRATOR: The storm is now so bad,

neither the ships nor the U-boats can move.

Until it passes, the convoy can only watch and wait.

- Do you ever lose faith Jean?

I mean, in what we're doing here.

- I can't afford to lose faith.

How can I teach what I don't believe?

ROBERTS: This year has been catastrophic.

There's lots of people in this place

that would close us down just like that.

- There are no guarantees.

We've never claimed that.

ROBERTS: We can drill them all we like. We can... talk.

Set the stopwatch.

But we can't recreate the ocean, the wind, the waves.

- The terror.

We will prevail.

I know we will.

- Yes, yes. Of course.

RICHIE: The relationship between Roberts and Laidlaw

seems to be one of very, very close cooperation.

A mutual trust, a mutual respect

and this is something that's really quite unusual

for the age, for the era.

- I have every faith.

- I suppose that's what we have now, faith.

- No. We have this.

What we teach them.

- We do.

NARRATOR: As the storm begins to abate,

HMS Duncan's fuel is now dangerously low.

- Western approaches aren't gonna like it.

- Do you think I like it?

The last bloody thing I want to do, leave my charge. The last thing!

I've lives to protect on the ships and back home.

What choice have I got?

We've got just enough fuel to get us to St Johns, if that.

Or... we stay and we're towed.

DUNLOP: It may seem odd to us that any man, or indeed woman,

would want to remain

in a battle zone.

But Gretton, like most of the men fighting in this war,

there to win it, come what may.

GRETTON: Duncan, to detach.

Steer course for St Johns, Newfoundland.

Best speed.

NARRATOR: Forced to depart, Commander Gretton knows

he is leaving the convoy at the worst possible time.

STRONG: In the military,

if you are not able to take part in a battle

that you yourself have influenced,

it can be incredibly emotional.

It must have been heart-breaking.

NARRATOR: News of Gretton's departure from the convoy

soon reaches Admiral Horton.

- "Present weather conditions preclude oiling at sea.

Intend detaching."

And he's taking three other escort ships with him.

- That ship was built in the '30s.

It's not up to modern standards.

HORTON: Our commanders weren't trained to leave their charge,

especially not a commander like Gretton.

- With respect sir, I don't believe he had a choice.

- We all have to live with our decisions Roberts.

NARRATOR: It is now five days

since ONS-5 was spotted by U-boat 650.

As the convoy reaches the Black Pit,

Donitz is desperate for his wolfpack to attack.

- Message.

Utilise all means to listen.

Report every clue immediately.

Every chance must be taken.

Something can, and must, be achieved with 31 U-boats.

End.

MILNER: He's got his teeth into ONS-5

and by the time he's done ordering up U-boats to attack it,

there's around 40, 41.

Four times larger than the escort.

I mean, it's an overwhelming number of U-boats.

NARRATOR: Knowing that three days ago

her fiance's ship HMS Oribi joined the convoy,

Wren Christian Oldham refuses to leave the plotting room.

CHRISTIAN: Naturally, I needed to stay there.

There was no way that I could leave the plot

until the battle was decided.

It was a nightmare to feel so helpless,

waiting for news which didn't ever come.

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