The Science of D-Day

70 years ago, one of the greatest amphibious assaults in history

was launched from here on the south coast of England.

Fire! EXPLOSION

And within a matter of hours,

7,000 vessels had landed 156,000 troops on the beaches of Normandy.

'This is the day and this is the hour.'

It was a manoeuvre that changed the course of the War

and tested innovations in science and engineering for the first time.

'My name's Rob Bell, and I'm an engineer.

'I'm obsessed with discovering how machines work,

'from today's cutting edge technology...'

This is amazing.

'..to the engineering feats of the past.'

Wo-ho-how!

'On this programme, I'm going to be looking at the nuts and bolts

'which made such a staggering invasion possible.'

I've never experienced anything like this before.

'From giant troop-carrying gliders

'to tanks that could drive on water.'

Put that on the water and it floats.

'How necessity really did become the mother of invention.'

Liquid flame coming at you at great speed with a huge roar.

'Like many new inventions, not all of them worked,

'and the results were devastating.'

The carnage on that beach...

Thank God they never show pictures of it.

It's probably the biggest human undertaking of all time.

This is The Science of D-Day.

'The planning started in 1943 for a mass invasion of Northern France.

'But everyone knew that launching an attack from the sea was

'a highly risky business.

'The Germans were expecting us and held a strong defensive position.'

Churchill was desperate to avoid mistakes that would cost lives.

In 1942, an Allied force was sent on a daring raid of Dieppe.

Many of them left from here in Southampton,

but it was clear from the start they just didn't have the right kit.

'As the tanks were driven onto the beaches,

'their rubber tracks were shredded by the shingle,

'and the bogged down vehicles became sitting ducks for German guns.

'The infantry were slaughtered.'

4,000 men were left behind, either killed, wounded or taken prisoner.

If Britain were to try anything like this botched attempt again,

it needed new engineering solutions.

'It was clear tanks had to be completely rethought,

'with a specific task in mind.

'New planes were needed.

'They had to be bigger, but lighter and stronger.

'Ships needed to be fast, silent, but capable of withstanding

'the attack they'd undoubtedly meet on the other side.

'Capable of the biggest invasion the world had ever seen.

'At the Tank Museum in Dorset,

'a strange looking object symbolises the ingenuity of the solutions made.

'In terms of design and function,

'it's got all my engineering juices flowing.'

This is the Sherman Duplex Drive tank,

more commonly known as the Donald Duck.

No prizes for guessing why.

It's 30 tonnes of iron and steel that's been adapted to float.

This one here is one of the best remaining examples of

the tanks that were floated in on D-Day.

And I've never seen anything like it before.

The Allies need some form of armour on the beach very quickly

to support the infantry

because they're going to have to engage with these German positions.

We know where some of them are, we don't know where all of them are,

but their worry was, if you put all your tanks onto one landing craft,

and that landing craft hits a mine or is hit by German shell fire,

you're losing the lot.

So they loved this idea of the floating tank

because it's a way of spreading your risk.

So how did the floating tank actually work, then, David?

The whole idea behind the floating tank is displacement.

If you can push out, as it were, enough water,

-you can make anything float.

-OK.

So you need to displace 30 tonnes of water,

because a Sherman tank weighs about 30 tonnes.

So, what we've got here, here's a model of a Sherman tank.

-This one's only plastic.

-OK.

But if we imagine that, 30 tonnes, put it in the water, it sinks.

-It works its way down.

-Down it goes.

Now, if we put a canvas screen round the same type of model,

so, another 30-tonne Sherman tank.

-It's the same tank.

-Same tank there.

-Yeah.

-Canvas screen around,

put that on the water,

and it floats.

So, then, the height and volume of that screen was calculated and

designed to be able to displace the amount of water, 30 tonnes of water,

so that this tank could actually float into shore.

And, of course, propellers at the back,

so they propel you through at about three miles an hour.

And then, once you're on the beach, on land...?

Canvas screen is collapsed

and there you are ready with a fighting tank straight away.

'To transform a 30-tonne Sherman into a seaworthy machine,

'it had to undergo a dramatic transformation.

'The lower hull was sealed, a propeller drive was added,

'and a pair of propellers at the rear provided propulsion.

'The base of the canvas flotation screen was attached to

'a horizontal boat-shaped platform welded to the tank's hull.

'The screen was supported by horizontal metal hoops

'and by 36 vertical rubber tubes.

'A system of compressed air bottles

'and pipes inflated the rubber tubes to give the curtain rigidity.

'The screen could be erected in 15 minutes,

'and quickly collapsed once the tank reached the shore.

'This is an early version of the Donald Duck,

'a modified Valentine tank.

'It's been lovingly restored by tank enthusiast Jonathan Pearson.'

One of the odd things about this is when you find out that

actually the pieces are just standard commercial parts,

they're brake parts or bits off lorries or bits off trains,

erm, that have been put together in an unusual way.

Very little of it was actually designed from scratch.

-So, John, can we see the propeller at the back?

-Yeah, certainly.

So, even though the turret's facing this way, this is the back?

Yes, this is the back of the vehicle.

That was one of the problems was the turret had to be reversed.

When you're going cross-country, it's lifted up

and locked up in the raise position, which takes it out of gear.

And then the steering consists of...

..that.

So you'd have the captain of the tank,

for want of a better word, would be at this tiller here then?

Yes, for the initial run ashore.

Er, when you get closer to the enemy shore

then you take this tiller out, he'd get inside the turret,

and it's the driver that would be driving by, er, by compass.

'After 20 years of restoration,

'thanks to Jonathan this tank is now in complete working order.

'And, boy, am I in for a real treat!'

OK, yeah, we've got...

We're moving here. Wow!

HE CHUCKLES

It's coming alive.

-So these are right up with pressure. Oh, wow, yeah.

-Lean on the top.

AIR HISSES

So that's air that's keeping that up?

We haven't put the metal props in.

To have faith that this was actually going to float

and that you weren't going to get sunk down in a tank...

would just have been... I don't know how they did it.

Absolute courage and bravery

and trust in the designers

and the engineers behind this whole project.

It's just outstanding.

'And it was these Valentine tanks that provided invaluable lessons,

'but at great cost to lives.

'Overlooking Studland Bay in Dorset stands Fort Henry,

'one of D-Day's most important relics.'

Six weeks before June 6th 1944,

troops gathered here in these waters behind me to rehearse the invasion.

It was the largest training exercise for what would be an epic operation.

'And watching over them were names etched in British history.

'Sir Winston Churchill, King George VI

'and General Eisenhower, Supreme Commander of the Allied Forces,

'all gathered here to direct operations.

'They'd chosen Studland Beach

'because it so closely resembles the beaches of Northern France.

'Operation Smash, as it was called, was the first major test

'for the Valentine DD tank, but on the day of the exercise,

'the weather was bleak.'

Despite concerns from engineers

over how the DDs would cope in swelling seas,

orders were given to launch.

The Valentines' six-cylinder diesel engines roared into life.

Fumes and sea spray choked the atmosphere.

And as they were lowered into the water,

waves broke against the massive bow ramps of the landing craft.

The soldiers on board ran into difficulties immediately,

with the canvas screens providing little,

if any, protection from the incoming waves.

Six tanks plummeted to the seabed,

and tragically, not everyone on board managed to swim free in time.

Six men lost their lives that day,

some trapped beneath the canvas screens constructed to protect them,

but which proved no match for the power of the sea.

'This memorial remembers the men who were lost.'

There was a heavy, heavy swell that, er,

that just knocked the screens of the tanks flat.

'Cecil Newton was part of the DD Tank Division,

'and witnessed the disaster from the shore.'

There were drivers trapped,

with a canvas screen

coming down on top of them and trapping them in the Valentine.

Our particular tank crew came back in,

and they didn't like to talk about it. They were traumatised.

They were 20-year-olds. It must have been terrible for them.

We learned the lesson,

take the tanks as close to the beach as possible if the sea is choppy.

Take the risk, take your landing craft in closer

before you launch the floating tanks.

'Six weeks later,

'Cecil found himself approaching the shores of Normandy.'

I can always remember the French coast.

A grey, grey strip in front of you. Mm.

'Thanks to the knowledge gained from Exercise Smash,

'Cecil's Donald Duck tank was launched close to the beach.'

-You were in the Sherman tank and you were floating to shore.

-Yeah.

-There was absolute confidence in the canopy...

-Yeah, no problems at all.

-No problem at all.

-..in the design.

-Yeah, no problem at all.

Didn't think about it.

'The Donald Duck tank was one of many specialised vehicles

'dreamt up by a man who wasn't even in the Army when war was declared.

'Major Percy Hobart was a bit of a maverick in his day.

'Having been in charge of tank brigades in the '30s,'

he was then retired, partly due to his unconventional ideas

about replacing manpower and horses with machines.

'At the time, the military establishment just wasn't ready

'for that kind of thinking, but now it needed it.

'Hobart was languishing in the Home Guard in 1940

'when he was summoned to Chequers by Sir Winston Churchill.

'He went on to oversee the design of some incredible vehicles

'which were all used in D-Day.

'Collectively, they were known as "Hobart's Funnies,"

'but, crucially, they worked.

'The most feared of all was the flame-throwing Crocodile.'

The mere sound of a Crocodile jetting flame towards a German strong point

or bunker was 99% certain to actually get the occupants to surrender,

put their arms up and surrender, er, it was that terrifying.

It's a kind of a vision from Hell, I suppose.

Erm, liquid flame coming at you at great speed

with a huge roar,

it's kind of a scene almost from the, you know, Dante's Inferno, it's...

So, er, overall, then,

would you say that Hobart was critical to the success of D-Day?

Erm, yeah, I think he was,

and his contribution as the Commander of the 79th Armoured Division

was vital, in as much as it allowed the troops

and the armour and the vehicles to actually get off the beaches

more quickly than they would have been able to

without specialised engineer support.

Erm, so, obviously, save time, save lives.

While Hobart was working on how to transport tanks onto the

shores of Normandy, others had to work on transporting the manpower.

How to get thousands and thousands of soldiers

onto the beaches to fight.

ARTILLERY THUNDERS

During the First World War, British soldiers invading

Gallipoli in Turkey had nothing but rowing boats, not dissimilar

to this, providing little, if any, protection from artillery.

Thousands of lives were lost, and it was clear that new methods

had to be engineered for the biggest invasion ever planned.

'So the Ministry of Defence put out a tender for a landing carrier,

'and it was the Southampton shipbuilder Thornycroft

'that came up with the winning design.

'The Landing Craft Assault was 41 feet long and weighed four tonnes.

'Due to the shortage of steel,

'the hull was made from Canadian rock elm.

'Armoured steel plates gave strength and protection.

'The two Ford V8 engines were

'so quiet they couldn't be heard from 25 yards away.

'Together with its low profile on the water, this made it stealthy.

'Unlike most landers,

'the LCA had a long central well section fitted with three benches,

'one centre, one port and one starboard for seating troops.

'Immediately behind the bulkhead were the steering shelter

'on the starboard and the Lewis gun shelter on the port.

'The steering shelter was fitted with a telegraph and voice pipe

'for communication with the stoker.

'These photographs show Allied troops in an LCA.

'The craft may have been well designed,

'but the journey was unforgettable.

'At the D-Day Museum in Southsea, I've come to meet a man with

'first hand experience of landing on the beaches of Normandy.'

Quickly went seasick. Very quickly.

'Frank Rosier was only 18

'when he made the crossing over to France.'

Smell of engine oil, it was hot, and it was pretty awful.

The expression was, going out,

"Soon as we get off this so-and-so boat the better."

-Oh, really?

-Yeah.

-So it was...

You know, I mean, even knowing what we were going into,

"Soon as we get off this boat the better."

-Wow.

-No, we'd had enough.

The first arrival on the beach, and that shock-horror sort of thing,

was among the worst days of my life.

You knew what was coming and you knew what was happening,

you wonder how you're going to...

You know, "Am I going to get out of this?"

I mean, fair didn't come into it.

It was... I felt so ill. I mean, as soon as you hit the shore

that sickness seemed to disappear, but then the horror on the beach.

I mean, I won't try to describe to you what was on that beach.

You're family.

You are as close as that. You are brothers.

Our orders were if your mate got it you left him there.

Sounds easy to do but it's not,

leaving a mate on a beach like that, it's quite a bit to do.

This 18-year-old lad had never seen a dead person in his life,

even in the Blitz, and for a few seconds,

the carnage on that beach...

Just the shock of it.

You know, you... Thank God they never show pictures of it,

but, I'm holding me rifle if you imagine.

You know, a few seconds.

You know, that's a boy, that's a kid.

It's absolutely impossible for me to imagine, or even picture,

what it would have been like for someone like Frank, on D-Day,

travelling across the Channel on something not dissimilar to this,

feeling more sick

than probably you've ever felt before in your life,

with the sound of war going on all the way around you,

and knowing, when you got off this and back on shore,

there's no guarantee that you're going to get out of that alive.

When I was 18, the biggest things I had to worry about was acne

and what I was going to do after school.

It's just such a completely different world

and enormously humbling, and really hits home how brave those guys were.

It took a long time for me to ever go to sea again.

It, er, you know, and even then, if I go now over to France, I will

find a corner and I will sit there and I won't move till we get there.

This is the American equivalent of the LCA.

It's nicknamed a Higgins boat after its designer, Andrew Higgins,

and was designed to carry up to 36 troops.

'As those landing carriers

'made their way onto the Normandy beaches,

'they were faced with a barrage of German bullets.

'To have any chance of survival,

'Allied troops needed masses of firepower.

'I've come to the Royal Armouries Museum at Fort Nelson

'in Hampshire to learn about a weapon of choice

'that had been in development since the First World War.'

ARTILLERY THUNDERS

'During the Great War, the Army used two sorts of field gun.

'The 18 pounder and the 4½ inch Howitzer.

'The Howitzer had a high angle of fire, useful for firing over walls.

'The 18=pounder was used for flat direct fire, like shooting at tanks.

'But carrying two field guns around was hefty work.

'The Army needed a machine

'that would combine both directions of fire.

'The 25-pounder was born.

'The gun weighed almost two tonnes

'and had a barrel length of eight feet.

'It could shoot a shell almost 12,000 metres.

'That's seven and a half miles.

'A crew of six could fire almost six rounds per minute.

'For rapid traversing, it had a turnable platform under the wheels,

'but crucially for D-Day, the addition of the muzzle brake

'allowed the firing of a supercharged shell.'

The muzzle brake was very necessary because

when you engage tanks you need an extra charge called a supercharge.

And that would have had, what,

too much stress on the whole gun without...?

Without the muzzle brake, yes,

and therefore, you would reduce the life of the barrel.

I mean, what I love about this, it's a relatively simple

piece of engineering design, but brought about by necessity.

And I guess, arguably,

could have been part of the success of the Allied forces on D-Day.

Indeed. Quite a simple device, as is often the case with these things.

It was a gunners' favourite,

and served in most theatres during the Second World War.

So we're lucky enough today to be able to

actually fire this 25 pounder that we've got out here

so we can see specifically how the muzzle brake works at the end there.

And we've got a super-slow-mo camera filming on that so we can actually

see the effect of this quite simple but brilliant piece of engineering.

So, Phil, talk us through it. What do we need? What have we got here?

OK, what we have in our special box is a genuine,

er, 25 pounder cartridge,

and inside here we have a small brown paper bag,

eight ounces of gunpowder,

with a white paper bag of wood shavings on top.

-OK, so that's the wood shavings we can see there.

-In the white bag.

-And behind that is...?

-Brown paper bag, eight ounces of gunpowder.

-Boom.

Then at this end, because the firing pin has to

act on that little silvery primer...

-Yep.

-..which will spark into the bag charge.

-And that's that in the centre there.

-That little silvery bit there, yes.

So that gets tapped, sparked, bang.

Hopefully.

OK, I'll just check we're safe.

OK, counting down.

Five, four, three, two, one, fire.

GUN BOOMS

RATTLING

Wo-ho-ho-ho-how!

That was amazing, look at the smoke still coming out of this!

It's incredible! So, would that be hot to touch right now, or...?

It's warm, it's warm.

Yeah, OK, it's quite warm, yeah. OK.

'We can see the effects of the muzzle brake

'from the slow motion camera.

'When the gas behind a fired round exits the barrel the muzzle

'partially diverts combustion gases at a sideways angle,

'reducing the recoil and stress on the gun.'

The smell you're getting from the gunpowder

as well as just the boom when it went!

You know it's going to be loud, but, yeah, that was loud.

And, even though it's a smaller charge as well,

you still feel that there's a kick, sat on that seat there,

the whole thing just, whoa, gives a kick. There's some power in that.

So you can imagine what it was like for a detachment of men

who were having to fire as many as they could,

as many rounds as they could in a minute.

-So another one straight back in, bang?

-Yeah. Indeed.

That's got my heart going, it's got my heart going.

I'm stood here now and I can feel my adrenaline racing through me.

-I'm pleased, I'm pleased.

-That's an impressive piece of kit.

GUN BOOMS

Getting men onto the beaches was a perilous task.

Getting them in behind enemy lines was downright lethal.

In the early hours of June 6th,

a small detachment of British airborne troops

took off from a small airfield in Dorset, RAF Tarrant Rushton.

Their aim, to capture two bridges in Normandy, to prevent

the Germans from sending reinforcements to the beaches.

-'Cut loose.'

-Roger. So long.

'Trying to deliver 181 soldiers within walking distance of

two bridges in Northern France posed a particular problem.

'Parachuting men in wasn't an option.

'It just wasn't accurate enough, and landing a motor powered plane

'would be noisy and ruin any element of surprise.'

-There's a fancy fold that just went in there.

-Looks good.

-Best of luck.

-May the best man win.

-Or the best design win.

'Here at Leon Solent in Hampshire,

'Henry Freeborn is a bit of a whizz at flying planes.'

Go on! Ohhh!

-What?!

-HENRY LAUGHS

Another go?

'Well, I'm certainly no aircraft designer!'

So much better! So much better, you blew me out of the water!

'But unlike me,

it took just ten months for British engineers to design a machine

'that was capable of delivering

'an entire troop of men into enemy territory.'

Keeping the wings level now.

'To breach the German defences they needed accuracy and stealth.'

We're now airborne.

A bit of hail from above.

What they came up with was a glider like this one,

but on a giant scale, capable of carrying not just two

but 25 men.

'That glider was the Airspeed Horsa.

'The Horsa had a wingspan of 27 metres and was 20 metres long.

'When fully loaded, it weighed almost seven tonnes.

'The fuselage was built in three sections bolted together.

'The front section held the pilot's compartment

'and main freight loading door.

'The middle section was accommodation for troops or freight.

'And the rear section supported the tail unit.

'The wing carried large barn door flaps which,

'when lowered, made a steep, high rate of descent landing

'possible, allowing the pilots to land in constricted spaces.'

The premise of a glider is that it's small and it's light.

There are no engines to take up space or create weight,

and these 60-foot wings are what's keeping us up, catching thermals

with minimal drag, and keeping us up in the air for as long as possible.

And that's just with me and Henry on board.

As we come in to land now,

I can only imagine what it must have felt like for those soldiers going

into Normandy, not knowing at all what awaited them on the other side.

We're coming down in a nice flat airfield.

They would have come down in whatever field or flat area

that they would have been able to find

for that element of surprise and stealth

to try and make their landing.

Now, that was, that might have seemed like

a fairly bumpy landing for us.

Just imagine what that would have been like in a Horsa.

Whoo!

'At the Army Flying Museum in Middle Wallop,

'they have one of the last remaining gliders.'

And here it is, the Airspeed Horsa.

Around 700 of these specifically designed assault gliders were built,

tested and maintained at the Airspeed Factory in Christchurch.

'By the very nature of gliders, pilots only had one go at landing.

In fact, they were designed almost exclusively for one-way missions.'

To allow quick disembarkation of troops and equipment,

small explosives could be detonated to break off the tail section.

But touching the aircraft down in the first place was often perilous.

Glider troops had an alarmingly high fatality rate,

with most deaths happening on landing.

'Scenes like this were not uncommon.

'BBC war reporter Chester Wilmot recorded this radio broadcast

'on D-Day in a Horsa.

'It describes the dramatic experience of landing

'in one of these gliders.'

'We stiffened ourselves for the jolt of the touchdown and lifted our feet

'clear of the floor in case something might rip through the belly.

'And as the wheels bounced and lurched over the furrows and ditches,

'we heard the harsh straining of the wooden fuselage,

'the crash of posts hitting the nose and undercarriage.

'We shouted with joy and relief and bundled out into the field.

'Around us we could see the silhouettes of other gliders,

'twisted and wrecked, making grotesque patterns against the sky.

'Some had buried their noses in the soil.

'Two had crashed into each other.'

'Luckily, the Pegasus mission was a success.

'The bridge was heavily guarded by Germans,

'but the Horsa gliders allowed the British troops to land unnoticed.'

The bridges were captured with relative ease, the mission

hailed as the single most important 10 minutes of the War.

Technology was the silent ally.

It paved the way for men to fight on the beaches of Normandy,

and without it, victory might not have come so soon.