(airplanes roaring) (Dermot) In every battle of every war, there's a defining moment when victory is seized.

(dramatic music) I'm Dermot O'Leary, and I've been fascinated by history since I was a boy.

How can that lose to that?

The gun is tiny.

My passion is discovering the stories of ordinary people and forgotten heroes caught up in the chaos of war.

(woman) I could hear the bombs in the water.

(Dermot) In this series, we're tackling some of the most important battles in British history.

This is a perfect killing zone.

(Dermot) And unpacking the crucial two days that secured victory.

(gunfire) Alongside me is ex-Royal Marine Arthur Williams, an expert on the machinery of war.

-Bloomin' heck!

-He takes to the skies for a bird's-eye view of the action.

(Arthur) Tens of thousands of men would have lost their lives fighting over these tiny little locations.

(Dermot) Historian and battlefield guide Lucy Betteridge-Dyson traces events on the ground.

(Lucy) For the soldiers, it was like arriving in hell.

(Dermot) Always going the extra mile to understand life for the average soldier on the frontline.

(Lucy) It would've been incredibly difficult just to exist, never mind to fight.

(Dermot) Using a high-tech war table, we explore key moments and turning points...

They'd have created this pincer movement, and it would be a total victory.

(Dermot) ...to reveal both their impact and importance.

(Lucy) The RAF were busy fighting the Luftwaffe further inland.

(Dermot) We'll delve deep into the most momentous and terrifying hours in military history... (explosions) ...to reveal how battles were lost and won.

(cannon fires) (dark music) ♪ (tense music) The evacuation of the British Army from France in 1940 was one of the pivotal moments of the Second World War.

Had it failed, it could've spelled the end of the war for Britain.

(flames crackling, plane wailing) We're homing in on a crucial 48 hours of this battle to understand why the evacuation was necessary, how events unfolded, and the jaw-dropping mistakes, good fortune, and heroics that got the British out.

♪ Dunkirk.

Everyone has heard of Dunkirk.

It's a name that exists in this country's myth and its legend, and "Dunkirk spirit" is a phrase that's used and misused often today.

So what is it about Dunkirk that warrants this 48 Hours treatment, Lucy?

Well, Dunkirk is interesting because it's an evacuation, but we often talk about it as a victory, which, in itself, is a bit odd.

Operation Dynamo, the official name for the evacuation of Dunkirk, actually lasted for about ten days, and we're looking at 48 hours that I think particularly demonstrates why it was such an incredible, incredible thing to pull off.

(grim music) (Dermot) Britain entered the Second World War in September 1939, but over the winter, little fighting took place, a period known as the Phoney War.

On the 10th of May, 1940, Winston Churchill became Prime Minister, and on the same day, the Germans invaded France.

This was known as the blitzkrieg.

♪ The Germans advanced with astonishing speed, catching British and French forces by surprise and trapping almost 400,000 troops at Dunkirk.

To understand how these huge numbers got out, we're using one ship's daring missions over two crucial days.

The heroism of HMS Worcester unlocks the wider story of Operation Dynamo, something Churchill called a "miracle of deliverance."

♪ Using our war table, we can show the situation at the start of the battle.

♪ (Arthur) So how did the British Expeditionary Force end up being pinned down in Dunkirk?

Well, basically, we gotta look at what the Germans were doing.

You got Army Group B in the north that are making steady progress through Belgium, but then most importantly, you've got Army Group A which are coming in underneath the British.

They're fighting desperately hard and fast to get through to the coast at Abbeville and Amiens.

If they do that, they'd have created this pincer movement, they'd have isolated the British from the French in the south, and it would be a total victory.

So, what 48 hours are we focusing on?

We're gonna look at the 31st of May and the 1st of June.

Those two days really give us a fantastic snapshot of pretty much Operation Dynamo as a whole.

(propeller whirring) (dark music) ♪ As midnight struck on the 31st of May, 1940, Operation Dynamo was entering its sixth day.

Over the previous days, Operation Dynamo had successfully evacuated 126,000 men, and General Gort, who was in charge of the overall evacuation, still believed that there were about 80,000 in and around the town that they needed to get out.

That number, in fact, was closer to 200,000, so there was still a lot of work to be done.

(solemn music) (Dermot) Down on the ground, Lucy's following in the footsteps of the British Tommies making their way to the beaches.

(Lucy) Today, Dunkirk is a peaceful port town, like many others scattered along the French coast.

In May 1940, it's hard to express just what a state of chaos this place was in.

(explosions) (dreary music) Fighting around the town had been vicious, and in their desperation to reach the coastline, troops had abandoned what kit and equipment they could, often racing towards the sea with just the clothes on their back and with what little food they could carry.

Descriptions of what faced men when they reached Dunkirk are truly harrowing.

Sergeant A. Bruce of the 7th Field Company wrote, "As we trudged on, we passed horses, their stomachs ripped open and entrails scattered all over the place.

Men were lying there in grotesque attitude of death, eyes and mouths wide open.

It was hard to believe that they had ever been human beings.

Here they lay where they had died, like dogs that had been run over in the street."

♪ We think of Dunkirk as the scene of a miracle, but for the soldiers waiting on the beaches, it was like arriving in hell.

(waves crashing) ♪ (Dermot) By the early hours of the 31st of May, Operation Dynamo was entering its sixth day.

For the soldiers gathered on the beaches, a devastating weapon at sea was threatening to derail the entire evacuation.

♪ It sounds like Dunkirk was a really hideous place to be.

Did the night offer any respite at all?

Well, you'd like to think so, wouldn't you?

Of course, the air element can't really function effectively at night, so they haven't got Stuka dive bombers coming on them, but what they do have is another German weapon that's just as deadly, the Schnellboot or the S-boat.

Shortly after our 48-hour period begins, this French vessel, the Siroco, is meandering off the coast, she's got about 600 embarked men on board, and two S-boats come along, fire off their torpedoes, and wound her badly.

When daylight breaks, the Stukas come in, and pretty much all of the 600 men and 59 crew die.

It's one of the most tragic stories about Dunkirk.

(seagulls calling) (Dermot) Eighty years on, there's only one S-boat left in the world.

Arthur's getting an exclusive peek at this restoration with Dr. Harry Bennett of Plymouth University.

(Harry) All right, Arthur.

Well, welcome to, uh, the sole surviving German motor torpedo boat of the Second World War.

You've got 110 foot here of mean nastiness in the form of a World War II German warship.

(Arthur) Yeah.

(grim music) (Harry) You've got four torpedoes, two torpedo tubes at the front and two reloads.

You've got cannon and machine guns that is skimming across the surface of the sea at over 40 knots.

(Arthur) How do you use this thing?

Presumably it's used very quick, sort of hit-and-run tactics.

(Harry) This is a kind of an ambush predator.

So you are literally going to go hell for leather in the direction of the target, close with it.

When you're from about 3,000 yards down to 1,000 yards, you can launch torpedoes.

(explosion) These things are very hard to hit, and they're very hard to kill.

They're so fast-moving.

So this is a real problem for the Allies.

For the British in particular, the kinds of impact that these things are having on the Dunkirk evacuation is deeply troubling, deeply worrying indeed.

(dark music) (Dermot) Under the cover of darkness on the night of the 31st of May, HMS Worcester, our British destroyer, was loaded up with 900 men for her fourth rescue mission in four days, but she knew the S-boats were a massive threat.

(waves crashing) At 2:00 a.m., they attacked.

(explosions) In a desperate attempt to escape, the Worcester ran aground on a sandbank.

It was now a race against time to refloat her.

As her engines roared and strained, the S-boats closed in.

Then she suddenly shot forward, escaping for the safety of the English coast.

(light music) To settle shredded nerves, the crew brewed up a traditional naval concoction called Pusser's Kye, and I've tracked down the recipe of this life-restoring brew.

So break a small bar of plain chocolate into pieces, and then, uh, add one hot cup of water, which I sincerely hope-- one for the chef-- which I sincerely hope is hot enough.

Okay, that looks good.

It says heat up the chocolate until it's melted, which we are almost there with, and then add a whole tin... (laughing) ...of condensed milk.

Now, you have to be a certain age to remember this.

My childhood was far more evaporated milk, but this stuff, oh, wow.

I mean, that's just... (laughing) So that's the condensed milk being stirred in, and then lastly, "add copious amounts," it says, "of sugar/rum, to taste."

So, get her in.

(stirring) All right, let's give this a go.

Oh yeah.

I mean, that's nice now, but if I've been stranded in Dunkirk without anything to eat or drink, scared witless and without any sleep for days, this is manna from heaven.

Oh.

Ooh, you know about it though.

(mellow music) (Dermot) As the early hours tick by, those waiting in the dunes and on the beaches hoped that dawn would bring salvation.

They had precious little food or water, and most had been involved in the terrifying and desperate retreat over the last two weeks.

As the Germans slowly tightened their grip around the town of Dunkirk, hundreds of thousands of British lives hang in the balance.

(dark music) The escape of the British Army from Dunkirk has become the stuff of Second World War legend.

Forty-eight crucial hours would hold the key to success or failure.

But on the morning of the 31st of May, 1940, success was far from assured.

Two hundred thousand soldiers were still trying to get to safety.

(rumbling) (seagulls calling) (grim music) (Arthur) The British troops were subjected to a ruthless and relentless bombing campaign, both being shelled from inland but also from the air as well from Stukas, Ju 88 dive bombers, Heinkel 111s.

Eighty years on, as we're flying over the town, the port, now, you can still see evidence of that.

♪ (Dermot) On the beach below, Lucy is exploring a relic of Dunkirk with battlefield guide Mike Peters.

(Mike) What you can see here, Lucy, is the wreck of HMS Crested Eagle, which was involved in Operation Dynamo.

Obviously didn't make it home.

(Lucy) So, Mike, how did this ship end up here in 1940?

(Mike) Crested Eagle makes a run across from UK.

The captain, Lieutenant Commander Bernard Booth, embarks 600 people.

As Booth casts off his ropes and turns away to head back to England, the Crested Eagle is spotted by a flight of Stukas.

She's hit by five bombs, so she catches fire very quickly.

And Booth, in his accounts after the war, says she was on fire from stem to stern.

So he has a dilemma.

He knows she's not gonna make it back to England, but he cannot abandon ship there and he cannot allow the Crested Eagle to sink because it'll obstruct other ships relaying back to England.

So he turns away and runs along the coast here, still under attack, and his plan is to find a sandbank and run her aground so that the survivors will be able to swim, wade, whatever, get back to the sand dunes, and live to fight another day.

(Lucy) A chance at surviving.

(Mike) Yes, absolutely that.

At one point, there are 200 survivors in the water trying to make it back, just that short distance across there to where the sand dunes are.

At that point, the Luftwaffe swoop down again and begin to strafe, machine-gunning the survivors in the water who were helpless.

(dreary music) (Lucy) So often, we think about the ships returning, and we forget about the ones that didn't.

♪ So the logistics of getting so many men off of this beach was a huge problem.

(Mike) It is because, you know, in the main, the larger ships cannot get close to the beach and it takes time to load that many people.

So this is where the Miracle of Dunkirk, the Little Ships, the whole myth is born because they already have a register of pleasure craft and small boats in the UK, so if they can get them across here and use them to establish a link between the water line and the offshore ships... (Lucy) And increase the speed of... (Mike) Massively enhances lift capacity and increase the turnover and also reduce the time that the big ships are sat there waiting when they're vulnerable to Stuka attack.

(solemn music) (Dermot) In the early hours of the 31st of May, beach commander Bill Tennant sent his now legendary request back to Britain: "Every available ship will be required at Dunkirk during the next two hours to evacuate the rest of the army."

♪ (seagulls calling) ♪ So, Lucy, now we get to the part of Dunkirk which is enshrined in legend, the small boats.

(Lucy) We all heard of the small boats, but they weren't really doing what many people think.

They weren't going from Britain to Dunkirk and carrying troops all the way back home.

Their main job was to ferry troops from the beaches to the troopships and carriers that were waiting offshore.

By 2:30 p.m., the small boats had made a line from Ramsgate to Dunkirk around five miles long, which was truly amazing.

(dreary music) (Dermot) There were 800 small boats involved in the evacuation.

Less than a fifth still survive.

♪ I'm meeting Jodi Smith who owns one of these boats, Papillon, and whose grandfather captained a small ship during Operation Dynamo.

Jodi!

-Morning, Dermot!

-Oh!

(Jodi) Welcome to Papillon.

(Dermot) Could not be happier to be on Papillon.

(Jodi) Welcome aboard.

-Straight down?

-Yes, yeah.

♪ (Dermot) So tell us about your grandfather.

(Jodi) My grandfather was William Smith, Bill.

He was working on Gainsborough Trader when he got the call from the Ministry of Transport, and they called up for him to take part in Operation Dynamo.

(Dermot) Did you know him at all?

Did you get to know him?

(Jodi) Yeah, he died when I was 12 years old, so I did know him.

(Dermot) So, Jodi, tell us what happened to your grandfather on the 31st of May.

(Jodi) He left Ramsgate, and they arrived in Dunkirk under a bomb attack early evening, and they worked throughout the night ferrying troops from the beaches and the makeshift piers onto the biggest destroyers.

(Dermot) And that's--straight away, as soon as he got there, he was given that brief, I guess, just to get to the beaches and get them off.

(Jodi) Yes, yeah.

(Dermot) I mean, he, the whole crew, must have been terrified.

(Jodi) They must have been.

They had no idea what they were gonna be requisitioned to do until they got to Ramsgate and they were issued the orders.

It must have been so frightening.

(Dermot) Absolutely.

So how long was he there?

(Jodi) It was only overnight because he had to go back for fuel, and then they came on back.

(Dermot) So how many men did your grandfather bring back?

(Jodi) Hundred and forty.

(Dermot) Incredible.

(bright music) ♪ As the small ships headed for Dunkirk, HMS Worcester was back in Dover, divers checking her propellers for damage.

(spirited piano music) By late afternoon, she was heading back out, but not for the beaches.

This time, her destination was a structure in Dunkirk Harbour called the mole.

(Lucy) So, Mike, we're here at the mole, and what is a mole?

(Mike) It's sea defenses.

So a harbor needs to be protected from tide and wind.

It's basically a wall, so what you're looking at really is the remnants of the Eastern Mole, which is what Bill Tennant, the naval commander in Dunkirk, wanted to use to bring his heavy ships in.

The Western Mole on the other side was unusable, the harbor was unusable, so this was a centerpiece of Operation Dynamo.

Without this flimsy structure, Dynamo wouldn't have achieved anywhere near the figures that it did.

Two-thirds of the 330,000 troops that are lifted out of Dunkirk, they come along this mole.

(Lucy) So, the mole that we're looking at the remnants of here really was a kind of-- the last artery, the last lifeline out of Dunkirk.

(Mike) I think that's a really good description of it, actually.

♪ (dramatic music) ♪ (Dermot) It was 9:00 p.m. when HMS Worcester docked at the mole.

♪ People were still pouring into Dunkirk.

♪ The German advance hadn't just pushed the army into retreat.

Thousands of civilians were also fleeing for the coast.

♪ Ninety-one-year-old Regine Gray was one of them.

She now lives in Berkshire and has never told her story publicly before.

And let's go back to 1940 and your experiences as a...nine-year-old?

Yeah, okay, what are your memories?

One particular morning, there were planes flying very low over Brussels, and they were throwing down leaflets, and my mother went down to pick one of the leaflets up, and it said, "We're about to invade you."

They were crossing the border, and she just flipped... -And just decided?

-...and said, "We're going."

(Dermot) Yeah.

Were you always heading to Dunkirk, or... (Regine) Yes, because the Tommies had told my mother that there were always ships coming in, bringing troops into Dunkirk and going back out of Dunkirk.

So what are your memories of that journey from Brussels to Dunkirk?

We were walking along a lane, and there were lots of refugees.

We weren't the only ones.

And the planes came very low.

My mother realized they were coming too low, threw me into a ditch, and then jumped on top of me.

(she laughs) And when we got up, there were quite a few bodies lying around.

So they came-- they strafed the road?

Yeah.

-Yeah, refugees.

-Yeah.

-Yeah.

-You eventually get to Dunkirk.

What are your memories of the town?

The whole place was on fire.

You couldn't breathe.

You had to put your hand over your mouth.

And it... it was just black smoke, really.

And did you go-- What happens then?

Did you go down to the beach or did you try and-- (Regine) No, we didn't get to the beach.

We were in this-- like a big hangar, and she left me with the guard who was at the door.

Refugees all over this place.

I mean, it was full of people, and about half an hour later, she came back and said, "Come on."

I think we walked for about ten minutes, and we went actually in the port.

We weren't outside the port, we were in the port.

And we got on the ship, but we were the last people to board this destroyer.

Tell us what you remember from the journey.

We were shown to a cabin, and that's when we could hear the noises because we were in a cabin on the outside, and I could hear the bombs splashing in the water.

And the officer said to my mother, "Don't worry.

We've done this trip before.

We have been bombed before.

They don't seem to be able to hit us.

Don't worry about it.

We'll get you safely."

You know, they were so kind and... Is this a picture of your mother here?

(Regine) That's my mother and I when we arrived in England.

(Dermot) Wow.

You look so much like her.

-Do I?

-Yeah.

-No!

-I think so.

(Regine) No.

She was so much fun.

I mean, she looks very serious there, but she was always-- always saw the bright side of life.

It's a great thing.

(dark music) (Dermot) It's a privilege to meet perhaps the only living civilian escapee from Dunkirk and an incredibly lucky one.

Just a tiny handful were rescued.

Most were left at the mercy of the Germans.

Regine knows the destroyer carrying her to safety had a name beginning with W. Given the time and date, it's probable it was HMS Worcester.

The Worcester left the mole in the early hours of the 31st, the final stretch of her fifth trip to Dunkirk.

(Arthur) By the end of the 31st of May, 65,000 troops had been evacuated from the port of Dunkirk and the mole.

It was the most successful day of Operation Dynamo so far, but it was only possible because of a few thousand men that were defending the perimeter and keeping the Germans at bay, just.

(Dermot) With the German grip tightening, the 1st of June would be make or break for Britain.

Dunkirk conjures up images of the men stranded on the beaches, the RAF keeping the skies clear, and the small boats ferrying men from the beaches and the mole, but none of this would've been possible without the troops tasked with keeping the German advance at bay.

By the morning of the 1st of June, the situation was critical.

(tense music) By the 1st of June, the perimeter defenses around Dunkirk stretched just 25 miles long and 8 miles deep, following the canals surrounding the town.

They were hemmed in.

I'm meeting with historian James Holland at Bovington Tank Museum to find out how the German blitzkrieg had driven the British back so quickly.

♪ So, James, tell me about the famous blitzkrieg, and we know the word, "lightning war," -but what does it really mean?

-Well, it's interesting because when people talk about the blitzkrieg, they also talk about the Nazi war machine, and the really interesting thing is that, actually, it wasn't that much of a machine.

So the Germans have got 135 divisions for the blitzkrieg, which sounds like a lot.

-Yeah, that is a lot.

-But only--it is a lot-- but only 16 are mechanized.

So the other 119 are just operating with horse-and-cart and their own two feet.

So the 16 Panzer divisions in cahoots with the Luftwaffe, and the Luftwaffe is there to support the ground forces.

So this is a Panzer II here, and this is one of the most numerous tanks that the Germans have.

While the Germans have got these, and even smaller tanks than that, the French have got this, you know, and that's pretty big.

(Dermot) How can that possibly lose to that?

(James) Because that's faster, agile, all that sort of stuff, but they haven't got much firepower.

This has got the firepower, but it hasn't got-- they haven't got the means of communicating, and that is the key to the blitzkrieg is that the Germans are all radioed up, so you can all talk to each other, whereas these guys don't.

So what happens in the blitzkrieg is that the Germans can all communicate with each other, so they can exploit success.

(Dermot) Yeah, if you're having a kind of a fast war, a lightning-speed war, that's kind of what you want, right, because it's fast and maneuverable, and it's still pretty imposing if it turns up in your village, right?

(James) Yeah, yeah, yeah.

(soldiers singing) (upbeat music) ♪ (Dermot) Are you surprised that it worked as well as it did, blitzkrieg?

(James) For all the brilliance of the Germans tactically and operationally, it's definitely at least 50 percent French ineptitude.

Why on Earth then did the Germans not push through and wipe them out completely?

All the Germans have gotta do is close that ring around them, and it's, you know, you've got the whole lot in the bag.

That then could be the Second World War done.

Yeah, very possibly because there's a whole load of sort of political machinations going on back in Westminster.

(Dermot) Churchill would lose his job, Halifax comes in, sue for peace... -Right.

-Why didn't they do that?

(James) Well, this is because they make an absolutely catastrophic, potentially war-fatal mistake, which is the notorious Halt Order issued on the 24th of May.

(grim music) (Dermot) Without this pause in the advance, there would've been no troops left to rescue a week later in our 48 Hours.

So the Halt Order could not have been more central to the success of the Dunkirk evacuation.

Word went out to the German Panzer divisions to halt and allow their infantry to catch up, just when it appeared they would close the ring and capture the entire British Army.

It was an astonishing decision.

(James) This represents a massive schism between the High Command of the German Army.

You've got the conservatives, the old sort of Prussians who don't really understand this kind of newfangled, armored mobile warfare.

And so, von Rundstedt, who is the commander of Army Group A, says, "Okay, we're gonna halt them," and this order reaches the guys at the front, and they're all just going... -"What are you doing?"

-"What are you doing?

We've got them, you know, by the short and curlies, we've absolutely got them where we want them.

We've gotta get across the canal now!

This is insane!"

But it gets upheld, and when the Army Command hears this, he reverses it.

(Dermot) The German High Command realized von Rundstedt was making a mistake halting the advance at such a crucial moment, but when Hitler heard they were overruling one of his generals, he made a fateful decision.

And Hitler goes, "What?!

How dare such thing, you know, a decision of such importance be taken without consulting me?

Reverse it!

You're in charge, von Rundstedt.

You, you know, grip it."

So it gets reversed, and it's a catastrophic decision for the Germans.

It's just basically based on Hitler's... (James) Yeah, it's Hitler having a complete lack of appreciation of the situation, you know, not reading the rooms in any shape or form, and spiting himself just over his ego and his determination to humiliate his commanders, which is why the Halt Order was so catastrophic because it gave Britain the chance for an evacuation.

(Dermot) Hitler's disastrous decision gave the Allies time to establish a perimeter around Dunkirk, but when the Halt Order lifted, the Allies needed to haul back their renewed advance.

(gentle music) As dawn broke on the 1st of June, one company facing the German onslaught was about to write their name in history.

(Mike) This was the hard perimeter for the British Expeditionary Force.

This was where they established themselves along the Furnes-Bergues Canal which is just down in the dip across the road there, and this canal line is a significant obstacle.

(Lucy) Pretty formidable, isn't it, really?

(Mike) Yeah, it's a huge anti-tank ditch.

It's a defender's dream.

The Panzers can't just get across it.

This section of line here, now in front of us, is held by the East Lancashire Regiment, and they've got a thousand yards in old money, that's 914 meters of frontage to cover, with very few anti-tank weapons.

The East Lancashire are in the barn half left there, forward of us, and the Germans are advancing in the direction we're going.

The guy who's in charge here is a man called Captain Ervine-Andrews, and he is absolutely the right man for this job.

(airplane soaring) And he arrives, walks into the barn, takes control of the situation, and says, "We're really low on ammunition; I'll do the shooting."

He's a crack shot, gets himself up onto the second floor of the barn, and immediately begins to pick off Germans.

(bombs whistling, explosions) (Ervine-Andrews) They were out in the open.

I was in a barn.

They didn't know where I was.

It's all very quick.

If you fire accurately and you hit men, the others are discouraged.

It's when you fire a lot of ammunition and you don't do any damage that the other chaps are very brave and push on, but when they're suffering severe casualties, they are inclined to stop.

Ervine-Andrews is doing one shot, one kill, and this is a perfect killing zone.

He picks off, on his own, 17 German soldiers.

He then takes over the Bren gun as well, and he's firing it from his shoulder.

And a Bren gun is quite a heavy weapon.

They repel a series of determined German attacks mounted by 20th Motorized Division.

Eventually, they run so low on ammunition that Ervine-Andrews sends a message back again, he says, "Okay, we're gonna have to abandon position."

But he wins the first Victoria Cross of World War II.

(Dermot) Ervine-Andrews and his men held back the German assault for an astonishing ten hours, a period when tens of thousands of men escaped Dunkirk.

(tense music) As Andrews was holding off the Germans, in Dover, Commander Allison of HMS Worcester had a decision to make.

Having survived five trips, should he risk another?

Reminded by his lieutenant how many men were still in Dunkirk, the choice was easy.

Allison ordered the Worcester to sail once more, but he was unaware that, above Dunkirk, things were hotting up.

Actions in the skies were about to seriously impact the evacuations.

(gunfire, planes whirring) So, Lucy, at the time, the troops on the ground think the RAF aren't there for them.

-Is that right?

-Well, that's true as far as the men can see, but that's because the RAF were busy fighting the Luftwaffe further inland, trying to stop the German bombers from wreaking havoc on the beaches.

Yeah, one of the pilots flying that day is a personal hero of mine, actually, and the very reason and inspiration why I learnt to become a pilot, Douglas Bader, the legless fighter ace of what would go on to be the Battle of Britain, but here at Dunkirk, he's flying a fighter sweep over France, he actually finds a Messerschmitt 109 and latches onto the tail of him, introduces a short burst of his machine-gun fire, shoots the Me 109 down, and it turns out to be Bader's first kill.

(dramatic music) (Dermot) Bader was an RAF pilot who lost his legs in a flying accident.

Undaunted, he learnt to fly again and persuaded his superiors to put him on frontline duty.

To fly with prosthetic legs and then have the precision needed to down an enemy fighter was an incredible feat.

And at RAF Hendon, Arthur's searching Bader's log to see how he marked this triumph.

♪ I can't tell you how much I've been looking forward to this.

To have his log book here and have the opportunity to read through it for the first time is very special.

Look at that.

He's not got very good handwriting.

When I had my accident and lost the use of my legs, I was at a loss of what to do with life and what I was gonna do for work, and then I really had one of these eureka moments where I remembered back to the film "Reach for the Sky" as a child, all about Douglas Bader, and I just thought, "Oh, wow.

If he could do that back in those days, I'm sure there's something that I can do in the 21st century," and that's how I became a pilot.

It's all because of this chap, and here I am, looking through his log books.

Here we go.

Dunkirk patrol.

Look at that, "Dunkirk patrol, shot down one Me 109 in flames."

Wow, that's the entry of his first kill.

You know, we gotta spare a thought as well, actually, to what it must have been like to make such an entry in your log book.

This simple entry here signifies the end of somebody's life.

You mustn't forget that.

(grim music) ♪ (airplane roaring) (explosion) It's the afternoon of June the 1st in 1940, and the Luftwaffe launch another onslaught against the men on the beaches and the ships trying to rescue them.

Wave upon wave of bombers are now getting through, including the plane the British fear more than any other: the Ju 87, the Stuka.

(engines roaring) The weather that afternoon was clear and bright, perfect for flying, and Luftwaffe chief Hermann Goering ordered an all-out assault on the beaches.

(dreary music) (planes wailing) ♪ Arthur is meeting air historian Dr. Harry Raffal to uncover what made this plane so terrifying.

(Arthur) So, Harry, this Stuka, what was it designed to do?

(Harry) So it's designed to deliver a bomb very accurately onto its target, and that's the real benefit of dive bombing.

During the channel evacuations, for dive bombers, the Ju 87s are the most effective means of attacking shipping, particularly for destroyers of the Royal Navy which are fast-moving and agile and also have a reasonable amount of anti-aircraft fire.

This is the ideal weapon to get in and attack them.

(plane wailing) (explosion) On the 1st of June in particular, there are pockets where the Royal Air Force isn't able to effectively cover the evacuation, and when the Ju 87s arrive within those periods, they do great damage to the shipping for Royal Navy.

♪ (Arthur) And these airplanes possessed something else that made the whole experience even more terrifying.

(Harry) Yes, the trumpets of Jericho are fitted to the Ju 87, a propeller-driven siren designed to create a high-pitch wail as they're going into the dive and attacking troops on the ground, and it is designed to produce an intense psychological reaction from the troops that are under attack.

(plane wailing) Those first attacks, they have a huge impact, to have these things diving down on you, making this shrieking banshee noise.

(plane wailing) (Arthur) Do we have any idea just how much damage they caused during that evacuation period?

Well, on the 1st of June, 21 ships from the evacuation fleet are lost to German air attack, and a number of crews and captains during the course of the evacuation have to be relieved, particularly when they've come under sustained periods of dive-bombing attack.

-Have to be relieved?

-It's difficult to really wrap your head around just the impact that they would've had psychologically, to have to sit there and endure air attacks whilst you're trying to bring these men off the beaches.

It's not necessarily that they're in the area throughout the entire day, but sustained periods, it really does have an effect on the crews as well as the material destruction which the Luftwaffe is able to achieve during the evacuation.

(explosion) (grim music) ♪ (Arthur) This is a battle that's evolving by every single hour, and in the afternoon, there's a break in the weather, and so the German Luftwaffe are exploiting that, and it's literally filling the skies with aircraft.

(Dermot) So how did the Navy respond to that?

(Lucy) Well, it's so dangerous that, by about 1:45 p.m., Vice-Admiral Ramsay ordered a halt to daylight operations and for all the destroyers to return to harbor.

So what does that mean for the Worcester?

(Lucy) Well, it's an incredibly difficult situation for the captain.

Does he follow orders, or does he attempt to rescue more men?

(tense music) (Dermot) HMS Worcester had been in the thick of the action for six days, already rescuing over 3,500 men.

Now, as the Luftwaffe took control of the skies, she was facing her toughest challenge yet.

♪ (seagulls calling) (Lucy) At half past three, the Worcester was in the process of picking up survivors from two recent wrecks.

It was at this moment they received a signal from the Vice-Admiral at Dover to return to the harbor immediately, but Captain Allison of the Worcester was having none of it.

So close to Dunkirk, he decided to ignore the order and push on to the mole.

By 4:00 p.m., they had managed to load around 900 troops.

Now the question was, could they return to Dover with the Stukas swarming overhead?

(plane wailing) (dramatic music) ♪ (Dermot) As the Worcester set sail, swarms of Stukas gathered overhead.

♪ In the narrow sea passage, the Worcester could only go half speed.

♪ She comes under intense aerial attack.

They pinpoint her and dive on her.

♪ (plane wailing) (explosion) (Dermot) In the next half an hour, the ship was attacked by over 30 dive bombers.

♪ (Arthur) One of the most dramatic accounts of the voyage was written by a seaman called Gordon Bonney.

"We steamed up the narrow fairway, loaded to capacity.

Stukas hung above us like a pack of vultures before a mass of them came into attack."

♪ As the Worcester made it to the open sea, she sped up but was still targeted by around a hundred bombs, the closest landing just ten yards away.

♪ (Arthur) The Germans' bombs are set to explode not on the water but underneath the water, and what this does, when it explodes, it creates a shockwave that's designed to literally lift the ship up out of the water and break it in half.

♪ (Lucy) The Worcester's log states, "The bombing was accurate, and only a miracle prevented the ship being struck."

(plane wailing) Seaman Bonney recalls, "Stukas screamed, bombs landing all around the ship.

All hell let loose.

The pongos were having a go with their rifles and Bren guns.

A gunner's mate was riddled with shrapnel and collapsed down a ladder, and I thought to myself, 'This is it.

We can't come out of this lot.'"

Throughout the voyage, the Worcester's gun crews, together with the rescued soldiers, kept up fire against the attacking Stukas despite many being wounded or killed in the process.

They are thought to have downed three Stukas.

They did little to discourage the attacking Germans.

♪ (Arthur) Now out in the open channel, the Worcester is a sitting duck.

Her decks are packed with soldiers that have just been evacuated from Dunkirk, and the Stukas appear once again and press home their attack.

This time, their bombs are exploding on the surface of the water, not underneath, which is good for the ship but it's not good for the men on board.

The shrapnel literally rips them to shreds.

(planes wailing) (solemn music) ♪ (Lucy) Lofty Childs, a torpedo man on the Worcester's crew, watched as an engineer climbed a ladder to the engine room hatch only to fall back down, the top of his head blown off by shrapnel.

(Arthur) All of Worcester's guns are blazing to the sky.

The Stukas are returning their own fire.

(gunfire) One of the shells or bombs or bullets manages to get through into a particularly vulnerable point of the ship: its shell rack.

It's held right next to the medical bay, and it explodes.

It kills 46 men and injures another 180.

Electrical circuits are shot and the fuel tanks are damaged.

The engines stop.

The Worcester is now adrift five miles off the Kent Coast.

(Arthur) But they were through the worst of it.

Seaman Bonney recalls, "There were four of us on deck.

Silence.

No Stukas astern.

We looked at one another in disbelief.

They'd gone.

As I looked up and forward, I noted many bodies not moving among the army."

♪ (Lucy) Two tugs came out to tow the Worcester back to Dover, but even then, the ordeal wasn't over.

Severely damaged by the explosion, on entering the harbor, she collided with another troop ship limping back from Dunkirk.

The collision pitched dead and dying from the Worcester's deck into the sea, causing many of the wounded to drown on the verge of safety.

♪ (Dermot) On securing her alongside the dock, the captain of the Worcester, Commander Allison, was heard to remark, "Well, that finishes me with this ship."

♪ One ship in a vast flotilla, and one journey amongst many, but through this journey, perhaps we might get a little understanding as to what it took to rescue the BEF.

(melancholy music) ♪ So, guys, it's the end of an extraordinary 48 hours, but it's not the end of the battle, right?

(Lucy) No, it's not, but the reason why we picked the 31st of May and 1st of June to look at in Dunkirk is because these were the two days when the most soldiers were evacuated from the beaches, 132,000.

Lucy, from a wider perspective, what's the sort of landscape happening right now towards the end of this evacuation?

(Lucy) Well, you know, Dunkirk is interesting not just because of what happened on the beaches, not just getting those men off the beaches, but really the political implications of Dunkirk.

You've got to remember that Churchill had only been Prime Minister for around three weeks, so the success of this operation really solidified his place as Prime Minister.

Had the evacuations not gone to plan, there were plenty others in the Conservative Party who would've been willing and ready to go for a peace negotiation with Germany, which could've looked very similar to what happened in France and the Vichy regime.

Wow, so it's impossible to kind of overestimate Dunkirk's importance then.

I like to think, from a British perspective, really, the Second World War can be broken down into three chapters.

The first chapter is us getting socked and the withdrawal from France.

The end of that chapter is Dunkirk.

That's us coming back.

Then we enter chapter two, the consolidation, bringing America into the war, building our forces and technologies, and then chapter three begins with the invasion of D-Day and us taking the fight back to Germany.

So without those 48 hours and the time around with Dunkirk, a second stage never happens.

Yeah, absolutely, that's true, and not just for military reasons; political ones as well, as you've mentioned, Lucy.

(Dermot) So would it be right in thinking the outcome of the evacuation of Dunkirk genuinely changed the course of the Second World War?

(Arthur) Yes, absolutely.

(solemn music) ♪ (bright music)