0:00:02 > 0:00:0570 years ago, one of the greatest amphibious assaults in history
0:00:05 > 0:00:08was launched from here on the south coast of England.
0:00:08 > 0:00:10Fire! EXPLOSION
0:00:10 > 0:00:12And within a matter of hours,
0:00:12 > 0:00:177,000 vessels had landed 156,000 troops on the beaches of Normandy.
0:00:17 > 0:00:19'This is the day and this is the hour.'
0:00:19 > 0:00:21It was a manoeuvre that changed the course of the War
0:00:21 > 0:00:26and tested innovations in science and engineering for the first time.
0:00:26 > 0:00:28'My name's Rob Bell, and I'm an engineer.
0:00:28 > 0:00:30'I'm obsessed with discovering how machines work,
0:00:30 > 0:00:33'from today's cutting edge technology...'
0:00:33 > 0:00:34This is amazing.
0:00:34 > 0:00:36'..to the engineering feats of the past.'
0:00:36 > 0:00:38Wo-ho-how!
0:00:38 > 0:00:41'On this programme, I'm going to be looking at the nuts and bolts
0:00:41 > 0:00:44'which made such a staggering invasion possible.'
0:00:44 > 0:00:46I've never experienced anything like this before.
0:00:46 > 0:00:48'From giant troop-carrying gliders
0:00:48 > 0:00:51'to tanks that could drive on water.'
0:00:51 > 0:00:53Put that on the water and it floats.
0:00:53 > 0:00:57'How necessity really did become the mother of invention.'
0:00:57 > 0:01:01Liquid flame coming at you at great speed with a huge roar.
0:01:01 > 0:01:04'Like many new inventions, not all of them worked,
0:01:04 > 0:01:06'and the results were devastating.'
0:01:06 > 0:01:08The carnage on that beach...
0:01:08 > 0:01:11Thank God they never show pictures of it.
0:01:11 > 0:01:14It's probably the biggest human undertaking of all time.
0:01:15 > 0:01:18This is The Science of D-Day.
0:01:29 > 0:01:35'The planning started in 1943 for a mass invasion of Northern France.
0:01:35 > 0:01:38'But everyone knew that launching an attack from the sea was
0:01:38 > 0:01:40'a highly risky business.
0:01:40 > 0:01:44'The Germans were expecting us and held a strong defensive position.'
0:01:44 > 0:01:48Churchill was desperate to avoid mistakes that would cost lives.
0:01:48 > 0:01:52In 1942, an Allied force was sent on a daring raid of Dieppe.
0:01:52 > 0:01:55Many of them left from here in Southampton,
0:01:55 > 0:01:59but it was clear from the start they just didn't have the right kit.
0:01:59 > 0:02:01'As the tanks were driven onto the beaches,
0:02:01 > 0:02:04'their rubber tracks were shredded by the shingle,
0:02:04 > 0:02:08'and the bogged down vehicles became sitting ducks for German guns.
0:02:08 > 0:02:10'The infantry were slaughtered.'
0:02:11 > 0:02:174,000 men were left behind, either killed, wounded or taken prisoner.
0:02:17 > 0:02:20If Britain were to try anything like this botched attempt again,
0:02:20 > 0:02:23it needed new engineering solutions.
0:02:25 > 0:02:28'It was clear tanks had to be completely rethought,
0:02:28 > 0:02:30'with a specific task in mind.
0:02:30 > 0:02:32'New planes were needed.
0:02:32 > 0:02:35'They had to be bigger, but lighter and stronger.
0:02:35 > 0:02:40'Ships needed to be fast, silent, but capable of withstanding
0:02:40 > 0:02:43'the attack they'd undoubtedly meet on the other side.
0:02:43 > 0:02:47'Capable of the biggest invasion the world had ever seen.
0:02:53 > 0:02:55'At the Tank Museum in Dorset,
0:02:55 > 0:03:01'a strange looking object symbolises the ingenuity of the solutions made.
0:03:01 > 0:03:03'In terms of design and function,
0:03:03 > 0:03:06'it's got all my engineering juices flowing.'
0:03:06 > 0:03:09This is the Sherman Duplex Drive tank,
0:03:09 > 0:03:12more commonly known as the Donald Duck.
0:03:12 > 0:03:14No prizes for guessing why.
0:03:14 > 0:03:19It's 30 tonnes of iron and steel that's been adapted to float.
0:03:19 > 0:03:22This one here is one of the best remaining examples of
0:03:22 > 0:03:25the tanks that were floated in on D-Day.
0:03:25 > 0:03:28And I've never seen anything like it before.
0:03:31 > 0:03:36The Allies need some form of armour on the beach very quickly
0:03:36 > 0:03:38to support the infantry
0:03:38 > 0:03:41because they're going to have to engage with these German positions.
0:03:41 > 0:03:45We know where some of them are, we don't know where all of them are,
0:03:45 > 0:03:48but their worry was, if you put all your tanks onto one landing craft,
0:03:48 > 0:03:53and that landing craft hits a mine or is hit by German shell fire,
0:03:53 > 0:03:54you're losing the lot.
0:03:54 > 0:03:57So they loved this idea of the floating tank
0:03:57 > 0:03:59because it's a way of spreading your risk.
0:03:59 > 0:04:02So how did the floating tank actually work, then, David?
0:04:02 > 0:04:05The whole idea behind the floating tank is displacement.
0:04:05 > 0:04:09If you can push out, as it were, enough water,
0:04:09 > 0:04:11- you can make anything float.- OK.
0:04:11 > 0:04:14So you need to displace 30 tonnes of water,
0:04:14 > 0:04:16because a Sherman tank weighs about 30 tonnes.
0:04:16 > 0:04:19So, what we've got here, here's a model of a Sherman tank.
0:04:19 > 0:04:21- This one's only plastic.- OK.
0:04:21 > 0:04:24But if we imagine that, 30 tonnes, put it in the water, it sinks.
0:04:24 > 0:04:27- It works its way down.- Down it goes.
0:04:27 > 0:04:30Now, if we put a canvas screen round the same type of model,
0:04:30 > 0:04:32so, another 30-tonne Sherman tank.
0:04:32 > 0:04:35- It's the same tank.- Same tank there. - Yeah.- Canvas screen around,
0:04:35 > 0:04:37put that on the water,
0:04:37 > 0:04:39and it floats.
0:04:39 > 0:04:42So, then, the height and volume of that screen was calculated and
0:04:42 > 0:04:46designed to be able to displace the amount of water, 30 tonnes of water,
0:04:46 > 0:04:49so that this tank could actually float into shore.
0:04:49 > 0:04:51And, of course, propellers at the back,
0:04:51 > 0:04:54so they propel you through at about three miles an hour.
0:04:54 > 0:04:56And then, once you're on the beach, on land...?
0:04:56 > 0:04:58Canvas screen is collapsed
0:04:58 > 0:05:01and there you are ready with a fighting tank straight away.
0:05:01 > 0:05:05'To transform a 30-tonne Sherman into a seaworthy machine,
0:05:05 > 0:05:09'it had to undergo a dramatic transformation.
0:05:09 > 0:05:11'The lower hull was sealed, a propeller drive was added,
0:05:11 > 0:05:16'and a pair of propellers at the rear provided propulsion.
0:05:16 > 0:05:19'The base of the canvas flotation screen was attached to
0:05:19 > 0:05:22'a horizontal boat-shaped platform welded to the tank's hull.
0:05:24 > 0:05:27'The screen was supported by horizontal metal hoops
0:05:27 > 0:05:29'and by 36 vertical rubber tubes.
0:05:29 > 0:05:32'A system of compressed air bottles
0:05:32 > 0:05:35'and pipes inflated the rubber tubes to give the curtain rigidity.
0:05:35 > 0:05:38'The screen could be erected in 15 minutes,
0:05:38 > 0:05:41'and quickly collapsed once the tank reached the shore.
0:05:46 > 0:05:49'This is an early version of the Donald Duck,
0:05:49 > 0:05:50'a modified Valentine tank.
0:05:52 > 0:05:56'It's been lovingly restored by tank enthusiast Jonathan Pearson.'
0:05:56 > 0:05:59One of the odd things about this is when you find out that
0:05:59 > 0:06:02actually the pieces are just standard commercial parts,
0:06:02 > 0:06:06they're brake parts or bits off lorries or bits off trains,
0:06:06 > 0:06:09erm, that have been put together in an unusual way.
0:06:09 > 0:06:12Very little of it was actually designed from scratch.
0:06:12 > 0:06:15- So, John, can we see the propeller at the back?- Yeah, certainly.
0:06:15 > 0:06:18So, even though the turret's facing this way, this is the back?
0:06:18 > 0:06:19Yes, this is the back of the vehicle.
0:06:19 > 0:06:22That was one of the problems was the turret had to be reversed.
0:06:22 > 0:06:25When you're going cross-country, it's lifted up
0:06:25 > 0:06:29and locked up in the raise position, which takes it out of gear.
0:06:31 > 0:06:33And then the steering consists of...
0:06:34 > 0:06:36..that.
0:06:36 > 0:06:40So you'd have the captain of the tank,
0:06:40 > 0:06:43for want of a better word, would be at this tiller here then?
0:06:43 > 0:06:45Yes, for the initial run ashore.
0:06:45 > 0:06:47Er, when you get closer to the enemy shore
0:06:47 > 0:06:50then you take this tiller out, he'd get inside the turret,
0:06:50 > 0:06:55and it's the driver that would be driving by, er, by compass.
0:06:55 > 0:06:58'After 20 years of restoration,
0:06:58 > 0:07:02'thanks to Jonathan this tank is now in complete working order.
0:07:02 > 0:07:05'And, boy, am I in for a real treat!'
0:07:05 > 0:07:07OK, yeah, we've got...
0:07:07 > 0:07:09We're moving here. Wow!
0:07:09 > 0:07:10HE CHUCKLES
0:07:10 > 0:07:11It's coming alive.
0:07:13 > 0:07:17- So these are right up with pressure. Oh, wow, yeah.- Lean on the top.
0:07:17 > 0:07:19AIR HISSES
0:07:19 > 0:07:20So that's air that's keeping that up?
0:07:20 > 0:07:22We haven't put the metal props in.
0:07:24 > 0:07:27To have faith that this was actually going to float
0:07:27 > 0:07:31and that you weren't going to get sunk down in a tank...
0:07:31 > 0:07:35would just have been... I don't know how they did it.
0:07:35 > 0:07:37Absolute courage and bravery
0:07:37 > 0:07:40and trust in the designers
0:07:40 > 0:07:43and the engineers behind this whole project.
0:07:43 > 0:07:44It's just outstanding.
0:07:48 > 0:07:51'And it was these Valentine tanks that provided invaluable lessons,
0:07:51 > 0:07:54'but at great cost to lives.
0:07:58 > 0:08:02'Overlooking Studland Bay in Dorset stands Fort Henry,
0:08:02 > 0:08:04'one of D-Day's most important relics.'
0:08:05 > 0:08:09Six weeks before June 6th 1944,
0:08:09 > 0:08:13troops gathered here in these waters behind me to rehearse the invasion.
0:08:13 > 0:08:18It was the largest training exercise for what would be an epic operation.
0:08:18 > 0:08:21'And watching over them were names etched in British history.
0:08:21 > 0:08:24'Sir Winston Churchill, King George VI
0:08:24 > 0:08:29'and General Eisenhower, Supreme Commander of the Allied Forces,
0:08:29 > 0:08:32'all gathered here to direct operations.
0:08:33 > 0:08:35'They'd chosen Studland Beach
0:08:35 > 0:08:39'because it so closely resembles the beaches of Northern France.
0:08:39 > 0:08:43'Operation Smash, as it was called, was the first major test
0:08:43 > 0:08:46'for the Valentine DD tank, but on the day of the exercise,
0:08:46 > 0:08:47'the weather was bleak.'
0:08:50 > 0:08:52Despite concerns from engineers
0:08:52 > 0:08:55over how the DDs would cope in swelling seas,
0:08:55 > 0:08:57orders were given to launch.
0:08:57 > 0:09:01The Valentines' six-cylinder diesel engines roared into life.
0:09:01 > 0:09:04Fumes and sea spray choked the atmosphere.
0:09:04 > 0:09:06And as they were lowered into the water,
0:09:06 > 0:09:10waves broke against the massive bow ramps of the landing craft.
0:09:11 > 0:09:14The soldiers on board ran into difficulties immediately,
0:09:14 > 0:09:16with the canvas screens providing little,
0:09:16 > 0:09:20if any, protection from the incoming waves.
0:09:20 > 0:09:22Six tanks plummeted to the seabed,
0:09:22 > 0:09:27and tragically, not everyone on board managed to swim free in time.
0:09:28 > 0:09:31Six men lost their lives that day,
0:09:31 > 0:09:35some trapped beneath the canvas screens constructed to protect them,
0:09:35 > 0:09:38but which proved no match for the power of the sea.
0:09:42 > 0:09:46'This memorial remembers the men who were lost.'
0:09:49 > 0:09:53There was a heavy, heavy swell that, er,
0:09:53 > 0:09:58that just knocked the screens of the tanks flat.
0:09:58 > 0:10:02'Cecil Newton was part of the DD Tank Division,
0:10:02 > 0:10:05'and witnessed the disaster from the shore.'
0:10:05 > 0:10:07There were drivers trapped,
0:10:07 > 0:10:09with a canvas screen
0:10:09 > 0:10:15coming down on top of them and trapping them in the Valentine.
0:10:16 > 0:10:21Our particular tank crew came back in,
0:10:21 > 0:10:24and they didn't like to talk about it. They were traumatised.
0:10:24 > 0:10:28They were 20-year-olds. It must have been terrible for them.
0:10:30 > 0:10:31We learned the lesson,
0:10:31 > 0:10:36take the tanks as close to the beach as possible if the sea is choppy.
0:10:36 > 0:10:39Take the risk, take your landing craft in closer
0:10:39 > 0:10:42before you launch the floating tanks.
0:10:43 > 0:10:44'Six weeks later,
0:10:44 > 0:10:48'Cecil found himself approaching the shores of Normandy.'
0:10:48 > 0:10:51I can always remember the French coast.
0:10:51 > 0:10:56A grey, grey strip in front of you. Mm.
0:10:59 > 0:11:02'Thanks to the knowledge gained from Exercise Smash,
0:11:02 > 0:11:07'Cecil's Donald Duck tank was launched close to the beach.'
0:11:07 > 0:11:12- You were in the Sherman tank and you were floating to shore.- Yeah.
0:11:12 > 0:11:16- There was absolute confidence in the canopy...- Yeah, no problems at all.
0:11:16 > 0:11:20- No problem at all.- ..in the design. - Yeah, no problem at all.
0:11:20 > 0:11:22Didn't think about it.
0:11:25 > 0:11:28'The Donald Duck tank was one of many specialised vehicles
0:11:28 > 0:11:32'dreamt up by a man who wasn't even in the Army when war was declared.
0:11:32 > 0:11:36'Major Percy Hobart was a bit of a maverick in his day.
0:11:36 > 0:11:39'Having been in charge of tank brigades in the '30s,'
0:11:39 > 0:11:43he was then retired, partly due to his unconventional ideas
0:11:43 > 0:11:47about replacing manpower and horses with machines.
0:11:48 > 0:11:52'At the time, the military establishment just wasn't ready
0:11:52 > 0:11:56'for that kind of thinking, but now it needed it.
0:11:56 > 0:11:59'Hobart was languishing in the Home Guard in 1940
0:11:59 > 0:12:03'when he was summoned to Chequers by Sir Winston Churchill.
0:12:03 > 0:12:06'He went on to oversee the design of some incredible vehicles
0:12:06 > 0:12:08'which were all used in D-Day.
0:12:08 > 0:12:11'Collectively, they were known as "Hobart's Funnies,"
0:12:11 > 0:12:14'but, crucially, they worked.
0:12:14 > 0:12:17'The most feared of all was the flame-throwing Crocodile.'
0:12:18 > 0:12:23The mere sound of a Crocodile jetting flame towards a German strong point
0:12:23 > 0:12:28or bunker was 99% certain to actually get the occupants to surrender,
0:12:28 > 0:12:31put their arms up and surrender, er, it was that terrifying.
0:12:34 > 0:12:36It's a kind of a vision from Hell, I suppose.
0:12:36 > 0:12:39Erm, liquid flame coming at you at great speed
0:12:39 > 0:12:41with a huge roar,
0:12:41 > 0:12:46it's kind of a scene almost from the, you know, Dante's Inferno, it's...
0:12:46 > 0:12:47So, er, overall, then,
0:12:47 > 0:12:51would you say that Hobart was critical to the success of D-Day?
0:12:51 > 0:12:53Erm, yeah, I think he was,
0:12:53 > 0:12:57and his contribution as the Commander of the 79th Armoured Division
0:12:57 > 0:13:02was vital, in as much as it allowed the troops
0:13:02 > 0:13:05and the armour and the vehicles to actually get off the beaches
0:13:05 > 0:13:08more quickly than they would have been able to
0:13:08 > 0:13:11without specialised engineer support.
0:13:11 > 0:13:13Erm, so, obviously, save time, save lives.
0:13:21 > 0:13:24While Hobart was working on how to transport tanks onto the
0:13:24 > 0:13:29shores of Normandy, others had to work on transporting the manpower.
0:13:29 > 0:13:31How to get thousands and thousands of soldiers
0:13:31 > 0:13:33onto the beaches to fight.
0:13:33 > 0:13:35ARTILLERY THUNDERS
0:13:40 > 0:13:43During the First World War, British soldiers invading
0:13:43 > 0:13:47Gallipoli in Turkey had nothing but rowing boats, not dissimilar
0:13:47 > 0:13:51to this, providing little, if any, protection from artillery.
0:13:51 > 0:13:55Thousands of lives were lost, and it was clear that new methods
0:13:55 > 0:13:59had to be engineered for the biggest invasion ever planned.
0:14:00 > 0:14:04'So the Ministry of Defence put out a tender for a landing carrier,
0:14:04 > 0:14:08'and it was the Southampton shipbuilder Thornycroft
0:14:08 > 0:14:10'that came up with the winning design.
0:14:10 > 0:14:15'The Landing Craft Assault was 41 feet long and weighed four tonnes.
0:14:15 > 0:14:17'Due to the shortage of steel,
0:14:17 > 0:14:20'the hull was made from Canadian rock elm.
0:14:20 > 0:14:23'Armoured steel plates gave strength and protection.
0:14:24 > 0:14:25'The two Ford V8 engines were
0:14:25 > 0:14:29'so quiet they couldn't be heard from 25 yards away.
0:14:30 > 0:14:35'Together with its low profile on the water, this made it stealthy.
0:14:35 > 0:14:36'Unlike most landers,
0:14:36 > 0:14:40'the LCA had a long central well section fitted with three benches,
0:14:40 > 0:14:45'one centre, one port and one starboard for seating troops.
0:14:45 > 0:14:48'Immediately behind the bulkhead were the steering shelter
0:14:48 > 0:14:52'on the starboard and the Lewis gun shelter on the port.
0:14:52 > 0:14:55'The steering shelter was fitted with a telegraph and voice pipe
0:14:55 > 0:14:57'for communication with the stoker.
0:15:01 > 0:15:05'These photographs show Allied troops in an LCA.
0:15:05 > 0:15:07'The craft may have been well designed,
0:15:07 > 0:15:10'but the journey was unforgettable.
0:15:11 > 0:15:15'At the D-Day Museum in Southsea, I've come to meet a man with
0:15:15 > 0:15:18'first hand experience of landing on the beaches of Normandy.'
0:15:18 > 0:15:22Quickly went seasick. Very quickly.
0:15:22 > 0:15:24'Frank Rosier was only 18
0:15:24 > 0:15:26'when he made the crossing over to France.'
0:15:26 > 0:15:30Smell of engine oil, it was hot, and it was pretty awful.
0:15:30 > 0:15:32The expression was, going out,
0:15:32 > 0:15:35"Soon as we get off this so-and-so boat the better."
0:15:35 > 0:15:36- Oh, really?- Yeah.- So it was...
0:15:36 > 0:15:39You know, I mean, even knowing what we were going into,
0:15:39 > 0:15:41"Soon as we get off this boat the better."
0:15:41 > 0:15:42- Wow.- No, we'd had enough.
0:15:54 > 0:15:57The first arrival on the beach, and that shock-horror sort of thing,
0:15:57 > 0:15:59was among the worst days of my life.
0:16:01 > 0:16:03You knew what was coming and you knew what was happening,
0:16:03 > 0:16:05you wonder how you're going to...
0:16:05 > 0:16:07You know, "Am I going to get out of this?"
0:16:09 > 0:16:12I mean, fair didn't come into it.
0:16:12 > 0:16:15It was... I felt so ill. I mean, as soon as you hit the shore
0:16:15 > 0:16:20that sickness seemed to disappear, but then the horror on the beach.
0:16:20 > 0:16:23I mean, I won't try to describe to you what was on that beach.
0:16:24 > 0:16:27You're family.
0:16:27 > 0:16:29You are as close as that. You are brothers.
0:16:29 > 0:16:32Our orders were if your mate got it you left him there.
0:16:32 > 0:16:34Sounds easy to do but it's not,
0:16:34 > 0:16:38leaving a mate on a beach like that, it's quite a bit to do.
0:16:39 > 0:16:44This 18-year-old lad had never seen a dead person in his life,
0:16:44 > 0:16:47even in the Blitz, and for a few seconds,
0:16:47 > 0:16:49the carnage on that beach...
0:16:50 > 0:16:52Just the shock of it.
0:16:52 > 0:16:57You know, you... Thank God they never show pictures of it,
0:16:57 > 0:17:00but, I'm holding me rifle if you imagine.
0:17:00 > 0:17:03You know, a few seconds.
0:17:03 > 0:17:05You know, that's a boy, that's a kid.
0:17:12 > 0:17:17It's absolutely impossible for me to imagine, or even picture,
0:17:17 > 0:17:20what it would have been like for someone like Frank, on D-Day,
0:17:20 > 0:17:24travelling across the Channel on something not dissimilar to this,
0:17:24 > 0:17:25feeling more sick
0:17:25 > 0:17:29than probably you've ever felt before in your life,
0:17:29 > 0:17:32with the sound of war going on all the way around you,
0:17:32 > 0:17:35and knowing, when you got off this and back on shore,
0:17:35 > 0:17:39there's no guarantee that you're going to get out of that alive.
0:17:39 > 0:17:43When I was 18, the biggest things I had to worry about was acne
0:17:43 > 0:17:45and what I was going to do after school.
0:17:45 > 0:17:47It's just such a completely different world
0:17:47 > 0:17:53and enormously humbling, and really hits home how brave those guys were.
0:17:54 > 0:17:57It took a long time for me to ever go to sea again.
0:17:57 > 0:18:03It, er, you know, and even then, if I go now over to France, I will
0:18:03 > 0:18:07find a corner and I will sit there and I won't move till we get there.
0:18:10 > 0:18:13This is the American equivalent of the LCA.
0:18:13 > 0:18:17It's nicknamed a Higgins boat after its designer, Andrew Higgins,
0:18:17 > 0:18:21and was designed to carry up to 36 troops.
0:18:22 > 0:18:23'As those landing carriers
0:18:23 > 0:18:26'made their way onto the Normandy beaches,
0:18:26 > 0:18:29'they were faced with a barrage of German bullets.
0:18:29 > 0:18:31'To have any chance of survival,
0:18:31 > 0:18:35'Allied troops needed masses of firepower.
0:18:35 > 0:18:38'I've come to the Royal Armouries Museum at Fort Nelson
0:18:38 > 0:18:40'in Hampshire to learn about a weapon of choice
0:18:40 > 0:18:45'that had been in development since the First World War.'
0:18:45 > 0:18:47ARTILLERY THUNDERS
0:18:47 > 0:18:50'During the Great War, the Army used two sorts of field gun.
0:18:50 > 0:18:54'The 18 pounder and the 4½ inch Howitzer.
0:18:54 > 0:18:59'The Howitzer had a high angle of fire, useful for firing over walls.
0:18:59 > 0:19:04'The 18=pounder was used for flat direct fire, like shooting at tanks.
0:19:04 > 0:19:08'But carrying two field guns around was hefty work.
0:19:08 > 0:19:09'The Army needed a machine
0:19:09 > 0:19:12'that would combine both directions of fire.
0:19:12 > 0:19:14'The 25-pounder was born.
0:19:16 > 0:19:18'The gun weighed almost two tonnes
0:19:18 > 0:19:21'and had a barrel length of eight feet.
0:19:21 > 0:19:25'It could shoot a shell almost 12,000 metres.
0:19:25 > 0:19:27'That's seven and a half miles.
0:19:27 > 0:19:31'A crew of six could fire almost six rounds per minute.
0:19:31 > 0:19:35'For rapid traversing, it had a turnable platform under the wheels,
0:19:35 > 0:19:38'but crucially for D-Day, the addition of the muzzle brake
0:19:38 > 0:19:41'allowed the firing of a supercharged shell.'
0:19:43 > 0:19:48The muzzle brake was very necessary because
0:19:48 > 0:19:53when you engage tanks you need an extra charge called a supercharge.
0:19:53 > 0:19:55And that would have had, what,
0:19:55 > 0:19:57too much stress on the whole gun without...?
0:19:57 > 0:19:59Without the muzzle brake, yes,
0:19:59 > 0:20:03and therefore, you would reduce the life of the barrel.
0:20:03 > 0:20:06I mean, what I love about this, it's a relatively simple
0:20:06 > 0:20:10piece of engineering design, but brought about by necessity.
0:20:10 > 0:20:12And I guess, arguably,
0:20:12 > 0:20:15could have been part of the success of the Allied forces on D-Day.
0:20:15 > 0:20:21Indeed. Quite a simple device, as is often the case with these things.
0:20:21 > 0:20:22It was a gunners' favourite,
0:20:22 > 0:20:27and served in most theatres during the Second World War.
0:20:27 > 0:20:29So we're lucky enough today to be able to
0:20:29 > 0:20:32actually fire this 25 pounder that we've got out here
0:20:32 > 0:20:38so we can see specifically how the muzzle brake works at the end there.
0:20:38 > 0:20:42And we've got a super-slow-mo camera filming on that so we can actually
0:20:42 > 0:20:46see the effect of this quite simple but brilliant piece of engineering.
0:20:46 > 0:20:50So, Phil, talk us through it. What do we need? What have we got here?
0:20:50 > 0:20:55OK, what we have in our special box is a genuine,
0:20:55 > 0:20:59er, 25 pounder cartridge,
0:20:59 > 0:21:02and inside here we have a small brown paper bag,
0:21:02 > 0:21:04eight ounces of gunpowder,
0:21:04 > 0:21:07with a white paper bag of wood shavings on top.
0:21:07 > 0:21:11- OK, so that's the wood shavings we can see there.- In the white bag.
0:21:11 > 0:21:16- And behind that is...?- Brown paper bag, eight ounces of gunpowder.- Boom.
0:21:16 > 0:21:20Then at this end, because the firing pin has to
0:21:20 > 0:21:23act on that little silvery primer...
0:21:23 > 0:21:26- Yep.- ..which will spark into the bag charge.
0:21:26 > 0:21:30- And that's that in the centre there. - That little silvery bit there, yes.
0:21:30 > 0:21:32So that gets tapped, sparked, bang.
0:21:32 > 0:21:33Hopefully.
0:21:33 > 0:21:35OK, I'll just check we're safe.
0:21:35 > 0:21:37OK, counting down.
0:21:37 > 0:21:44Five, four, three, two, one, fire.
0:21:44 > 0:21:46GUN BOOMS
0:21:47 > 0:21:49RATTLING
0:21:50 > 0:21:52Wo-ho-ho-ho-how!
0:21:54 > 0:21:56That was amazing, look at the smoke still coming out of this!
0:21:56 > 0:22:00It's incredible! So, would that be hot to touch right now, or...?
0:22:00 > 0:22:02It's warm, it's warm.
0:22:02 > 0:22:05Yeah, OK, it's quite warm, yeah. OK.
0:22:05 > 0:22:07'We can see the effects of the muzzle brake
0:22:07 > 0:22:09'from the slow motion camera.
0:22:09 > 0:22:13'When the gas behind a fired round exits the barrel the muzzle
0:22:13 > 0:22:17'partially diverts combustion gases at a sideways angle,
0:22:17 > 0:22:20'reducing the recoil and stress on the gun.'
0:22:21 > 0:22:24The smell you're getting from the gunpowder
0:22:24 > 0:22:27as well as just the boom when it went!
0:22:27 > 0:22:29You know it's going to be loud, but, yeah, that was loud.
0:22:29 > 0:22:32And, even though it's a smaller charge as well,
0:22:32 > 0:22:35you still feel that there's a kick, sat on that seat there,
0:22:35 > 0:22:38the whole thing just, whoa, gives a kick. There's some power in that.
0:22:38 > 0:22:41So you can imagine what it was like for a detachment of men
0:22:41 > 0:22:45who were having to fire as many as they could,
0:22:45 > 0:22:47as many rounds as they could in a minute.
0:22:47 > 0:22:49- So another one straight back in, bang?- Yeah. Indeed.
0:22:49 > 0:22:52That's got my heart going, it's got my heart going.
0:22:52 > 0:22:55I'm stood here now and I can feel my adrenaline racing through me.
0:22:55 > 0:22:59- I'm pleased, I'm pleased. - That's an impressive piece of kit.
0:22:59 > 0:23:01GUN BOOMS
0:23:01 > 0:23:05Getting men onto the beaches was a perilous task.
0:23:05 > 0:23:09Getting them in behind enemy lines was downright lethal.
0:23:09 > 0:23:11In the early hours of June 6th,
0:23:11 > 0:23:13a small detachment of British airborne troops
0:23:13 > 0:23:18took off from a small airfield in Dorset, RAF Tarrant Rushton.
0:23:18 > 0:23:22Their aim, to capture two bridges in Normandy, to prevent
0:23:22 > 0:23:25the Germans from sending reinforcements to the beaches.
0:23:25 > 0:23:27- 'Cut loose.'- Roger. So long.
0:23:27 > 0:23:32'Trying to deliver 181 soldiers within walking distance of
0:23:32 > 0:23:35two bridges in Northern France posed a particular problem.
0:23:37 > 0:23:39'Parachuting men in wasn't an option.
0:23:39 > 0:23:43'It just wasn't accurate enough, and landing a motor powered plane
0:23:43 > 0:23:46'would be noisy and ruin any element of surprise.'
0:23:46 > 0:23:49- There's a fancy fold that just went in there.- Looks good.
0:23:49 > 0:23:52- Best of luck.- May the best man win. - Or the best design win.
0:23:52 > 0:23:54'Here at Leon Solent in Hampshire,
0:23:54 > 0:23:57'Henry Freeborn is a bit of a whizz at flying planes.'
0:23:57 > 0:23:59Go on! Ohhh!
0:24:01 > 0:24:03- What?! - HENRY LAUGHS
0:24:03 > 0:24:04Another go?
0:24:04 > 0:24:08'Well, I'm certainly no aircraft designer!'
0:24:08 > 0:24:12So much better! So much better, you blew me out of the water!
0:24:14 > 0:24:15'But unlike me,
0:24:15 > 0:24:18it took just ten months for British engineers to design a machine
0:24:18 > 0:24:20'that was capable of delivering
0:24:20 > 0:24:23'an entire troop of men into enemy territory.'
0:24:23 > 0:24:25Keeping the wings level now.
0:24:25 > 0:24:29'To breach the German defences they needed accuracy and stealth.'
0:24:29 > 0:24:31We're now airborne.
0:24:31 > 0:24:32A bit of hail from above.
0:24:37 > 0:24:40What they came up with was a glider like this one,
0:24:40 > 0:24:44but on a giant scale, capable of carrying not just two
0:24:44 > 0:24:46but 25 men.
0:24:48 > 0:24:51'That glider was the Airspeed Horsa.
0:24:51 > 0:24:56'The Horsa had a wingspan of 27 metres and was 20 metres long.
0:24:57 > 0:25:00'When fully loaded, it weighed almost seven tonnes.
0:25:00 > 0:25:04'The fuselage was built in three sections bolted together.
0:25:04 > 0:25:06'The front section held the pilot's compartment
0:25:06 > 0:25:08'and main freight loading door.
0:25:08 > 0:25:12'The middle section was accommodation for troops or freight.
0:25:12 > 0:25:15'And the rear section supported the tail unit.
0:25:15 > 0:25:17'The wing carried large barn door flaps which,
0:25:17 > 0:25:20'when lowered, made a steep, high rate of descent landing
0:25:20 > 0:25:24'possible, allowing the pilots to land in constricted spaces.'
0:25:26 > 0:25:30The premise of a glider is that it's small and it's light.
0:25:30 > 0:25:33There are no engines to take up space or create weight,
0:25:33 > 0:25:37and these 60-foot wings are what's keeping us up, catching thermals
0:25:37 > 0:25:41with minimal drag, and keeping us up in the air for as long as possible.
0:25:41 > 0:25:44And that's just with me and Henry on board.
0:25:47 > 0:25:48As we come in to land now,
0:25:48 > 0:25:51I can only imagine what it must have felt like for those soldiers going
0:25:51 > 0:25:56into Normandy, not knowing at all what awaited them on the other side.
0:25:58 > 0:26:00We're coming down in a nice flat airfield.
0:26:00 > 0:26:03They would have come down in whatever field or flat area
0:26:03 > 0:26:07that they would have been able to find
0:26:07 > 0:26:09for that element of surprise and stealth
0:26:09 > 0:26:11to try and make their landing.
0:26:21 > 0:26:24Now, that was, that might have seemed like
0:26:24 > 0:26:26a fairly bumpy landing for us.
0:26:26 > 0:26:29Just imagine what that would have been like in a Horsa.
0:26:29 > 0:26:30Whoo!
0:26:32 > 0:26:35'At the Army Flying Museum in Middle Wallop,
0:26:35 > 0:26:38'they have one of the last remaining gliders.'
0:26:38 > 0:26:41And here it is, the Airspeed Horsa.
0:26:41 > 0:26:45Around 700 of these specifically designed assault gliders were built,
0:26:45 > 0:26:50tested and maintained at the Airspeed Factory in Christchurch.
0:26:50 > 0:26:54'By the very nature of gliders, pilots only had one go at landing.
0:26:54 > 0:26:58In fact, they were designed almost exclusively for one-way missions.'
0:26:58 > 0:27:02To allow quick disembarkation of troops and equipment,
0:27:02 > 0:27:06small explosives could be detonated to break off the tail section.
0:27:06 > 0:27:10But touching the aircraft down in the first place was often perilous.
0:27:10 > 0:27:13Glider troops had an alarmingly high fatality rate,
0:27:13 > 0:27:16with most deaths happening on landing.
0:27:19 > 0:27:21'Scenes like this were not uncommon.
0:27:21 > 0:27:25'BBC war reporter Chester Wilmot recorded this radio broadcast
0:27:25 > 0:27:28'on D-Day in a Horsa.
0:27:28 > 0:27:30'It describes the dramatic experience of landing
0:27:30 > 0:27:32'in one of these gliders.'
0:27:32 > 0:27:36'We stiffened ourselves for the jolt of the touchdown and lifted our feet
0:27:36 > 0:27:39'clear of the floor in case something might rip through the belly.
0:27:39 > 0:27:43'And as the wheels bounced and lurched over the furrows and ditches,
0:27:43 > 0:27:46'we heard the harsh straining of the wooden fuselage,
0:27:46 > 0:27:49'the crash of posts hitting the nose and undercarriage.
0:27:49 > 0:27:52'We shouted with joy and relief and bundled out into the field.
0:27:52 > 0:27:55'Around us we could see the silhouettes of other gliders,
0:27:55 > 0:28:00'twisted and wrecked, making grotesque patterns against the sky.
0:28:00 > 0:28:03'Some had buried their noses in the soil.
0:28:03 > 0:28:05'Two had crashed into each other.'
0:28:06 > 0:28:09'Luckily, the Pegasus mission was a success.
0:28:09 > 0:28:11'The bridge was heavily guarded by Germans,
0:28:11 > 0:28:15'but the Horsa gliders allowed the British troops to land unnoticed.'
0:28:16 > 0:28:19The bridges were captured with relative ease, the mission
0:28:19 > 0:28:24hailed as the single most important 10 minutes of the War.
0:28:24 > 0:28:26Technology was the silent ally.
0:28:26 > 0:28:29It paved the way for men to fight on the beaches of Normandy,
0:28:29 > 0:28:32and without it, victory might not have come so soon.