Category
📚
LearningTranscript
00:00The north coast of Ireland has been a huge maritime highway for centuries.
00:13And that has meant that we have one of the greatest collections of shipwrecks anywhere in the world.
00:21This is such a special place for divers.
00:24The variety of sunken shipwrecks here is unique.
00:27I mean, there literally is nowhere else that has submarines, ocean-going liners, cargo ships.
00:34You know, it's all here.
00:3620 miles of the Irish coast.
00:43A specialist team are diving into history.
00:50It's mind-blowing to the scale of everything down there.
00:53It's quite sort of scary to see these things and what they were built to do.
01:00To rediscover the lost wrecks.
01:02These are really big things.
01:05And you just feel so small.
01:08Of World War II's longest and most critical battle.
01:19The Battle of the Atlantic.
01:21Up!
01:34By late 1942, war had been raging at sea for three years with huge losses on both sides.
01:40So many bodies washed ashore that the local authorities are talking about reopening famine pits.
01:50The deadly U-boat fleet, under the command of Admiral Karl de Nitz, was still aiming to sever the lifeline of convoys between Britain and her allies.
01:59There was a sheer number of U-boots now deployed to the Atlantic.
02:04And there was hardly any chance to escape the search lines.
02:08It was just easy prey out there.
02:11Whilst military strategists, led by Sir Max Horten, were desperately trying to outthink and outmaneuver the killer wolf packs of the German Kriegsmarine.
02:19This room would have been filled with men and women.
02:22And what they are doing here informs their commanders.
02:25And those are the people who can order action based on the intelligence that is coming from this map.
02:33A small city in Northern Ireland, the most westerly port in the UK, found itself at the heart of the fight.
02:41The hinge of which the Battle of the Atlantic moved was actually the city of Derry.
02:49In this deadly game of cat and mouse...
02:54The U-boots could hide themselves in the dark and attack whenever it's suited to them.
02:59The Hedgehog was the very latest and the most desperately secret weapon designed for the discomfort of U-boots.
03:05They never knew what hit them.
03:07The Allies and the Nazis were in a race against time and technology.
03:11It's not just one side winning the whole time.
03:14There's the punch and counterpunch.
03:15There's the technology introduced. There's the reaction from the Allies.
03:20For both sides, the stakes couldn't have been any higher.
03:26Winning the Battle of the Atlantic did not guarantee that the Allies would win the war.
03:30Total war means there's nothing between what the Nazis called the final victory or total defeat.
03:39Losing the Battle of the Atlantic would have meant that the Allies lost the war.
03:44So is the realisation of heavy losses at sea.
04:01Each sinking atoll in arms, medicines, food, robbed from a regiment in the field.
04:05In late 1942, early 1943, it certainly looked as if the Battle of the Atlantic was going the Germans way.
04:13In fact, the late Corelli Barnet in his history of the Royal Navy in the Second World War actually describes that period of late 1942, early 1943 as Donuts was torpedoing his way to victory.
04:27Three years into battle, British naval leaders are locked in a desperate struggle against their German counterparts.
04:36Vital convoys carrying supplies of food, fuel and war materials from America and Canada are key to Britain's survival.
04:44So the convoys were, you know, they were the lifeline. They were the lifeline.
04:49But with nearly 2,000 ships sunk and tens of thousands of lives lost, this lifeline is in danger of being severed.
04:58If we cannot get ships and men across the Atlantic Ocean to physically fight the war, there is no war.
05:05Britain cannot fight anymore. And then there is no D-Day. It could be the winning or the losing of the entire Second World War.
05:10Western Approaches Command HQ was based in Derby House in Liverpool. This bomb and gas-proof bunker has been preserved exactly as it was during the war.
05:27This is a nerve centre of what the Royal Navy is doing in the Battle of the Atlantic.
05:31And at any given moment during that battle, from February 1941, they can see what is happening at sea.
05:40When I started there, those markers we used reminded me of toys out of some children's game.
05:45But soon they became U-boats and ships carrying cargoes, food and supplies and weapons and men to use them.
05:51The vast majority of staff working around the clock in this room were from the Women's Royal Naval Service, known as Wrens.
06:01What they are doing here informs their commanders. So the Royal Air Force commanders are here and the Royal Navy are there.
06:08And the person in charge, Admiral Max Horton, Commander in Chief of Western Approaches Command, whose office is just up there,
06:13he's the one who can order the big actions based on what is happening in here.
06:22This looks like a big map, but there is actually a huge amount going on on this wall.
06:28So you've got the long coloured red strings, that's depicting the route that a convoy would take.
06:33The little cards with the names of the convoys and the numbers of the convoys, so that's telling you where is the convoy coming from and where is it going to.
06:43The little coloured tabs off the back, they are telling you what kind of naval escorts the convoys have got with them.
06:49Is it destroyers? Is it frigates?
06:51The little white lozenges are suspected U-boat sightings and they are changed to black lozenges when it is confirmed that a U-boat is definitely there.
07:00In the early months of 1943, mounting allied losses were grimly reflected on the walls of this secretive bunker.
07:12That looks like a cluster of colours on a plain old map, but what it actually is, is a depiction of a horrific situation playing out at sea.
07:21So you've got three suspected U-boats, the three white lozenges, but way more worryingly you've got two confirmed U-boats, the black lozenges.
07:31The convoy has come from Sydney via New York and it's heading to the UK, but the two red crosses means that two of those ships have been damaged and the red boat beneath is a ship that has been sunk.
07:43So that is loss of life.
07:44There are people in here who know people who are on these convoys. You have wrens in here who have brothers and cousins and friends on those ships.
07:53And they're looking at this map and they are willing those people to stay alive and they know that the work that they are doing will contribute toward that. It is a big morale issue and it's a very heavy place to work.
08:08The most strategic port in the fight against the U-boats was Lissahallie on the River Foil in Londonderry. It's where a young Bert Wurski grew up.
08:24Lissahallie was a very small village at the start, you know, but when you'd be looking up now, you would be seeing lines of battleships and destroyers that was lying there all the time during the war, coming and going from the Atlantic all the time to be refueled and rearmed at Lissahallie.
08:46Lissahallie. This is where it all happened for them. You had ships from America, Canada, Australia armed to the teeth.
08:58They had a thing called depth charges on the side of the destroyer and the depth charges was just what you would look at like no 50 gallon oil drums.
09:09They went over the U-boats, they released them one at a time and that's how they attacked the U-boats. It was unbelievable.
09:21One major issue for the Allies in the fight against the Nazi U-boat threat was the geographic and political complexities on the island of Ireland.
09:30We're on the shores of Loch Foil, this sea estuary, which during the Second World War would have been busy with escort ships from many, many allied nations protecting the convoys in the North Atlantic.
09:43Straight across from us is County Donegal, which is in Ireland and a separate jurisdiction. On the same side of the river Foil is the city of Londonderry or Derry, which is in the United Kingdom, the most westerly port in the United Kingdom and hence its critical importance in the Battle of the Atlantic.
10:02The island of Ireland had been partitioned in 1921. Northern Ireland, including Derry, remained part of the UK, but Ireland, then known as ERA, declared its neutrality at the outbreak of war in 1939.
10:18Thus, Ireland's unhappy history under British rule was an important factor in ERA's decision to remain neutral, a decision which the freedom-loving nations of the world found difficult to comprehend.
10:31Geography shapes history. Geography is destiny in a sense, and it certainly did a lot of shaping in the Second World War.
10:39Irish neutrality meant that ports once available to the British were no longer accessible, leaving Derry as the most strategically vital location in all of the UK.
10:51While the city and its port were critical to the escort ships in the Battle of the Atlantic, the area close by also provided a number of airfields. There were four of them in total.
11:02Those airfields all played a critical part right throughout the war.
11:07The quickest way out into the open Atlantic was due west from Derry, across county Donegal.
11:14But technically, this would have been a violation of Irish airspace.
11:19The aircraft taking off from there to fly out into the Atlantic could fly out over Donegal and did without any protest being made by the Irish government.
11:30Every minute saved getting to the Atlantic was an extra minute added to the patrol time over a convoy or in the area of the convoy to search for U-boats on the surface or other German naval vessels in the area.
11:46With this shortcut into the Atlantic coupled with advances in technology, planes providing air cover were now able to fly further with convoys to keep them safe from attack.
12:01But deadly U-boat wolf packs knew the limitations of the Allied air cover.
12:07There was still a vast area of ocean that planes couldn't reach.
12:12So there was a dangerous area that was called the Black Pit by some merchant mariners where simply they had no aerial protection.
12:21Convoys had to rely on their own destroyer screens defending them.
12:25So that was where U-boats would wait in wolf packs to attack convoys.
12:31And it's where some of the biggest convoy battles of the Second World War took place.
12:42There was a sheer number of U-boats now deployed to the Atlantic.
12:46And there was hardly any chance to escape the search lines which were spanning all across the Atlantic.
12:52So sooner or later, any convoy would be located by U-boat.
12:57Convoys had nowhere to hide.
13:06In March 1943, 95 merchant ships were torpedoed and sunk.
13:12One of the highest rates of monthly losses since the conflict began.
13:16To have any chance of winning the battle, the so-called Mid-Atlantic Gap had to be closed.
13:24Through May 1943, you've got these little merchant ships, either grain ships or oil tankers, which have their superstructure removed and a flat deck fitted to them.
13:36And they can operate three or four swordfish by planes.
13:40And there were over a hundred of them.
13:42So every convoy after May 1943 has got air cover.
13:47These merchant ships, converted to aircraft carriers, would be key in solving the crisis in the Mid-Atlantic.
13:54This open stretch of ocean was about to be closed off to U-boats.
13:59The flight crews for these ferry swordfish biplanes operated out of HMS Shrike, based at Maydown Airfield, just outside Derry.
14:12It was home to thousands of men from the British and Dutch Air Force.
14:16And it's where Alex and Jennifer's dad, Hugo Yellema, was posted.
14:21Dad was born in Java, in the Dutch East Indies.
14:24The Japanese invaded the north of the island.
14:27And he and other people were put on ships.
14:31There were five ships that went out.
14:33And Dad was only one of two that survived that.
14:37So, from the outset, he was very lucky to get away from Java.
14:4819-year-old Hugo joined the Dutch Air Arm and found himself stationed in Derry as a navigator.
14:54And he needed luck on his side.
14:56Because, as he soon found out, protecting convoys was a hazardous occupation.
15:01The pilot tried to take off again, but they clipped the side of the ship and they...
15:07Got ditched into the Atlantic.
15:09Yeah, and they were in the Atlantic for about an hour, the three of them.
15:20A budding photographer and artist, he collated a stunning scrapbook of personal photos and drawings, detailing his life, protecting the convoys.
15:31Yeah.
15:32Oh, look.
15:33Oh, look.
15:35It's Dad.
15:36That's a swordfish.
15:38And Dad painted that on the side of their fairy swordfish.
15:44And that's Dad.
15:45Yeah.
15:46Oh.
15:47Yeah.
15:48And there he is again.
15:49With his gunner and his pilot, probably.
15:51Yes.
15:52These aeroplanes were called string bags, because they apparently looked like they were just tied together with string.
16:00Yes.
16:01There were three seats.
16:02Yeah.
16:03And the pilot was in the front.
16:04Dad was in the middle.
16:06Mm-hm.
16:07And then this must be the gunner, because it looks like he's facing backwards.
16:11Dad said that when he was navigating, he was standing in this little open cockpit.
16:16In the middle of the Atlantic.
16:17Yeah.
16:18Return convoy crossings could take weeks, and a swordfish crew would work on rotation, keeping constant air cover above the ships.
16:28Everyone lends a hand in this vessel.
16:30Ships, crew and ground staff help with the aircraft.
16:33The ship's doctor tests the wind, and the ship's engineer is in charge of the arresting gear.
16:37Yeah.
16:38With average flights lasting hours in minus temperatures, it was grueling, yet vital work.
16:44There was one time that they almost ran out of fuel.
16:47Mm-hm.
16:48And they managed to get to Newfoundland.
16:52Newfoundland, yes.
16:53Newfoundland, yes.
16:54Newfoundland.
16:55Very, very luckily, flying up an inlet and suddenly found an aerodrome.
17:00Yeah.
17:01Very fortunate.
17:02Very fortunate.
17:03Also based at Maydown in Derry was a young wren from Belfast, Mary Piper, who was keeping her own record of life in Derry at the time.
17:16There seemed to be lots of dances, and I'm not sure whether Mum was organising them or whether she was going to them,
17:22but there was a dance here, there was a dance there, there was a dance there.
17:27Mum was organising a 21st birthday party in the White Horse Inn,
17:32and they'd invited, I think, eight of the officers.
17:36Six or eight, yes.
17:37From Dad's squadron, and Dad was one of them.
17:42This blossoming wartime romance between the young Dutch airman and a Belfast wren is beautifully captured in the pages of their scrapbooks.
17:51Oh, look at this.
17:52A never-to-be-forgotten night at the club with Hugo.
17:58Back to Belmont in the pouring rain in evening dress.
18:04But given Hugo's critical job protecting convoys, finding time for romance wasn't exactly easy.
18:16Received your letter. No leave permitted. Any chance of seeing you, Hugo.
18:23All is well. I'm missing you very much. Love, Hugo.
18:26Oh, Dad. That's very sweet.
18:29We have this amazing archive of things which, really, we never knew anything about until more recent years.
18:36No, we didn't.
18:37And we can now see how, you know, where they first met, how their relationship was developing, became engaged and then ultimately got married.
18:50I think Dad wrote to Mum and asked her to marry him.
18:54And then they decided they better go and see our grandfather, who lived on the Antrim Road in Belfast.
19:02So this was coming to probably Dad asking Grandpa if he could marry Mum.
19:08Yes. After he'd asked her.
19:10After he'd asked her, yes.
19:12As well as discovering their parents' incredible scrapbooks, the sisters also unearthed a rare film, which captures life on board a Mack ship at that time.
19:26Men are taking their lives in their hand. Guiding them in.
19:30I love that. Down a bit. Up a bit. Down a bit.
19:34Yeah, no. Yeah, trying to keep it. Get your head down.
19:36Yes, and then duck.
19:38It's very hairy, and the Mack ship, it's not static.
19:42It's A, it's moving forwards.
19:44Sideways. And sideways.
19:46So in bad weather, I think it was a very hazardous thing to land.
19:52There the air's coming in.
19:54There's a hook on the back of the plane for catching the...
19:56Yeah, there's the arrestor.
19:58Remarkably, it features their dad Hugo and his crewmates.
20:02That's Dad. There's Dad.
20:04Oh.
20:05Oh, for goodness sake.
20:07He's chewing gum too.
20:09They're just young lads lurking around. Look at that.
20:13Oh my goodness.
20:15There he is right there.
20:16They are really laughing.
20:17I mean, they're forgetting about the war and everything else that's going on.
20:21They're just having a bit of fun.
20:23Uh-huh. Uh-huh.
20:25Can you imagine Dad chewing gum?
20:27No, absolutely not, no.
20:28Absolutely not.
20:29Especially not as a dad and a father.
20:31No.
20:32No.
20:33We don't even know him as a young lad larking about like that.
20:36Uh-huh.
20:38With aircraft that could now spot and attack U-boats anywhere in the Atlantic...
20:44...the Allies were beginning to wrestle back advantage at sea.
20:48But wary of the Nazis' ability to quickly develop their own technology...
20:52...the Royal Navy were about to introduce a brand new weapon named hedgehog.
20:58A depth charge is one of the weapons they have been utilising against U-boats.
21:03But you have to be directly over the U-boat.
21:05There have to be perfect conditions for that to strike successfully.
21:09A hedgehog, on the other hand, doesn't need those conditions.
21:12Originally, depth charges were rolled off the stern of a ship...
21:17...or they were fired by mortars off the side or over the stern of the ship.
21:22This new system, hedgehog, was an array of, I think it was 24 small mortars...
21:31...launched basically simultaneously and firing forward over the bow of the ship.
21:38You've got seconds when a U-boat is about to dive.
21:41You need something that can make contact with it and explode very quickly.
21:45And that is what a hedgehog is.
21:47HMS Broadway, based out of Derry, was one of the first Royal Navy escort ships...
21:52...issued with this new weapon.
21:54Commanded by Irishman Evelyn Chavasse, his mission was to keep convoy safe...
21:59...and vital supply lines to the UK open at all costs.
22:04Evelyn Henry Chavasse was a regular Royal Navy officer.
22:09Very, very professional, as the Royal Navy's officers were.
22:14Born in County Waterford, he left to attend Naval College in England at just 13 years old.
22:21Even though his country of birth was neutral in the war...
22:25...he, like tens of thousands of others from Ireland, was proud to fight on the side of their allies.
22:30It's one of those complications of being Anglo-Irish.
22:37I mean, the thing about the Anglo-Irish is the fact that the Irish think we're English...
22:42...and the English know we aren't.
22:44We were brought up to be Irish, to respect everything about the Irish...
22:47...but we were open to what was happening to our nearest neighbours as well.
22:51Evelyn's unpublished memoir from his time during the Battle of the Atlantic...
22:55...details the new weapon they had been supplied with.
22:58The Hedgehog was the very latest, and at the same time the most desperately secret weapon...
23:03...designed for the discomfort of U-boats.
23:06If you had made a good shot, one or more of them would plunge down onto a U-boat...
23:11...with a bang and punch a neat hole in it.
23:13If you missed, there would be a sad silence.
23:16But the U-boat would not realise it had been shot at.
23:19You could then have another go.
23:21Despite showing its capability in Navy tests...
23:24...the Hedgehog was failing to live up to expectations in the immediate months after its introduction...
23:30...leading some in the Admiralty to question its effectiveness.
23:34Evelyn Chavasse would be the man to prove its worth...
23:37...on a critical convoy from Halifax to Liverpool.
23:40It's the first convoy that was ever supported by an aircraft carrier...
23:45...for the entire crossing of the Atlantic.
23:48Convoy HX-237 consisted of 46 ships with eight escorts.
23:55On the 12th of May 1943, it was attacked by a wolfpack of U-boats in the Mid-Atlantic.
24:05The pace was beginning to hot up a bit, and there's a lot of U-boats around them...
24:09...and clear to me that by this time several U-boats were in touch with the convoy, mostly a stern.
24:14One of those was U-89 with 48 sailors on board.
24:19U-89 was then engaged by Chavasse's destroyer HMS Broadway and the frigate HMS Lagan.
24:27U-89 did all sorts of changes of depth and direction to try to avoid being hit.
24:34One at least of the 24 hedgehog mortars fired by HMS Broadway hits U-89 and sends U-89 to the bottom.
24:47We do know this was the first time that Hedgehog had actually been guaranteed...
24:57...or certified to have had a hit and have sunk a submarine.
25:01The convoy lost three ships, but would ultimately make it to Liverpool with most of its vital supplies intact.
25:13A combination of aircraft and escorts equipped with the new hedgehog mortars sank three U-boats in that one attack.
25:21In the space of just a couple of months, it seemed the Allies were beginning to turn the tide against the U-boats.
25:36The Nazis were fiercely determined to win back the advantage at sea, but their losses were mounting.
25:43May 1943 saw the culmination of all these efforts on the British side and on the Allied side to defeat the U-boats.
25:52So the U-boats were rather surprised to find aircraft in the middle of the Atlantic.
25:58And these aircraft were of course equipped with highly effective anti-submarine weapons and the results came in quickly.
26:05It saw the loss of almost 40 boats in one month.
26:18That is almost one third of the total boats operational at that time in the Atlantic.
26:28This is Black May to the Kriegsmarine.
26:30You know, it's had many periods of success through the conflict, but this is one where to Donitz, to Vice Admiral Donitz, the head of the U-boats, that this looks like they've had it.
26:43Nearly 2,000 men perished aboard U-boats in May 1943.
26:48Amongst them was Admiral Karl Donitz's 21-year-old son, Peter.
26:54One of the main problems the Kriegsmarine was suffering during the war was the deprofessionalization of its crews.
27:01The number of trained U-boats men aboard newly built or newly constructed boats was just reduced to four or five at maximum.
27:09So to replace those crews that had been lost, the Kriegsmarine was forced to introduce untrained personnel from other branches in the Kriegsmarine.
27:21So the casualty rate for the U-boat crews, and particularly, you know, this really came on in the latter part of the war as the Allies got on top, was the highest of any armed service in any nation.
27:36It was absolutely incredible.
27:38So every able-bodied person was drafted in.
27:41On 24th of May 1943, Donitz stopped the tonnage war in the Atlantic.
27:50He stopped wolfpack tactics in the Atlantic.
27:53And then he ordered his boat to move further south in order to find so-called soft spot in the central Atlantic or even in the south Atlantic.
28:01But what he had not foreseen was that even in these areas, there were no longer any more soft spots.
28:07Germany's shocked that they didn't expect the Allies to be so successful in May 1943 against the U-boat.
28:15And Willy Warnock, who's the Irish minister in Berlin, reports back that Germany is looking for some new form of weapon, some new form of tactics to meet the Allies.
28:26Twenty miles off the Irish coast, the sunken wrecks of battle are giving up their secrets, revealing how the Nazis were rapidly developing technology to try and regain the upper hand.
28:42As with all of the back of the Atlantic, there's the punch and counterpunch technology introduced, there's the reaction from the Allies, and vice versa.
28:51Every time there was an advance by one side, the other sought to counter it.
28:56An expert team of divers, led by world-renowned underwater cameraman Rich Stevenson, are exploring U-218.
29:05Originally designed to lay mines in coastal waters, its mission became increasingly difficult due to advances in radar and air cover.
29:15The Kriegs marina believed a new piece of technology named snorkel could change how a U-boat operated and give them back their advantage.
29:24When we dived U-218, Barry pointed out the snorkel.
29:30Again, it looked like the day it was made, it was in a really incredible condition given the amount of years that it's been lying there on the seabed.
29:39A snorkel would extend to a length of eight and a half meters from the deck of the boat, effectively allowing it to breathe underwater.
29:49Introduction of the snorkel was a huge leap ahead for the German submarines because they didn't have to surface.
29:57Not having to surface then made you much, much less vulnerable.
30:06The snorkel turned these submersibles into complete submarines in terms of that they could stay submerged for longer periods,
30:13could reload their batteries and could travel being submerged at periscope depths.
30:18So once U-boots were able to stay submerged with the help of the snorkel, their chances to be located by enemy aircraft was almost nil.
30:29And then, typically at night, they would come up and start to engage targets.
30:35And this came very much to a surprise to the British Admiralty because thanks to the snorkel,
30:49they were now able to stay unmolested in these areas and even they achieved some success.
30:57Traditional U-boats, retrofitted with a snorkel, would still have a significant role to play in the battle,
31:04as the Allies would soon find out to their cost.
31:08But the Nazis were also secretly developing a completely new type of U-boat.
31:15Their most effective killing machine yet.
31:25This bunker stands for what the Germans called the total war.
31:34Total war means there's nothing between what the Nazis called the final victory or total defeat.
31:47They named this project Valentin.
31:50And it was located at the river Weser in the north of Germany.
31:54And it was huge.
31:55This concrete superstructure with a seven meter thick roof extended to the length of four football pitches.
32:04It was here that this brand new type of U-boat would be constructed in total secrecy.
32:10The Type 21, dubbed the Electroboat.
32:14The hope of the Nazis was to mass-produce Type 21 submarines on a really new system of assembly line.
32:26The idea was to put out one submarine each 56 hours.
32:31If you compare this to a 12-month building in the previous times with a conventional boat, the production figure was immense.
32:40So it would have increased the number of U-boats available to the Greeks marines to a very large number.
32:47Plans for the Electroboat were finalized in 1943 and the first vessels went into production at various locations across the Reich.
32:57It was the first U-boat that could truly be called a submarine, able to spend most of its time operating below the surface.
33:04It did this with the help of a massive battery compartment in the hull.
33:09The new Electroboat types were in a way revolutionary in terms of design.
33:16They applied for the first time streamlining.
33:19They had high underwater speed.
33:20They had very effective weaponry and detection systems.
33:24You've got this submarine that doesn't have to surface.
33:27It can stay submerged and fire.
33:29It's got more advanced weaponry.
33:31Its guns can be reloaded in quarter of the time they could before.
33:35It's an impressive feat.
33:37Convinced of the new vessel's potential, Grand Admiral Karl Donitz wanted this vast bunker complex to house a mass production facility.
33:47He gambled that the sheer number of these technically advanced boats rolling off the assembly lines would ultimately overwhelm the Allies.
33:57The problem was that these constructions were only able with the help of slave labor and prisoners of war at that time.
34:05Because the Germans were completely exhausted in terms of labor.
34:10It's very peaceful. It's very quiet. And especially today with the sunny weather.
34:17But it looked completely different 80 years ago.
34:19Because we are now standing at the beginning of what was the landscape of different camps where the post laborers were put.
34:28So there were barracks all over the place and there were barracks all over the place and there were guards all over the place, barbed wire, military structure to put people kept from different countries.
34:43And for different reasons, sent here to work.
35:00It was really like a concentration camp system.
35:06Among the 10,000 men sent to the camps at Bremen Farga were 32 Irishmen who had been captured on British merchant navy ships in the years before and taken prisoner.
35:17They belonged to the first groups of the people who were forced to work within the project of the bunker of Valentin construction site.
35:26The Irish seaman would be kept here for two years.
35:29The men were from both sides of the Irish border, but German officials eventually declared them all to be Irish.
35:41Now classified as civilians from a neutral country, their prisoner of war status was removed and they were offered contracts aboard German ships.
35:51When they refused to cooperate with the Nazis, they were sent to the punishment camp at Bremen Farga.
36:00The youngest of the group was 19-year-old Harry Callens from Derry, the city at the heart of the battle against the U-boats in the Atlantic.
36:16A seaman doesn't have a passport. What a seaman has is a discharge book.
36:22And so here's the very first ship he went on, the Culebra, in 1940.
36:28But this one then shows the Afrik Star. This was the ship that he went down on.
36:32And in this case, on the 29th of January 1941, they were discharged at sea because that's when they were captured and the boat was sank.
36:41And then his next voyage is 1946. Nobody in the family ever mentioned the war or being a prisoner of war. It just wasn't done.
36:53People came back from the war and they were all damaged people.
36:57It was only when Harry was in his mid-80s that Michelle finally got him to talk about his experiences.
37:05He found out that he was actually the last survivor. I asked him to please, please talk to us because you're the last one.
37:15And if you die, nobody is going to know anything about what happened to you guys. So you do need to talk.
37:23We were scared, boy. We were really afraid. We thought this is the end. We told our prisoners of war at this end.
37:33You're no civilians. And you'll do what we tell you to do. I cried. And a few mothers cried.
37:43And once I started down that road, it was like a tap opened.
37:49We saw so much death. It's an awful fear. It's a fear you have. And to know that you have definitely no control whatsoever over yourself.
38:01That you have to do as you're told.
38:05That's when it all came out, what he saw. The beatings, the people being shot, the bodies in the open graves.
38:13And it was really difficult for him.
38:16As thousands of forced labourers, including Harry and his fellow Irishmen, continued to toil on the bunker construction,
38:27the Nazis were increasingly pinning their hopes on the Electra boat to turn the tide in their favour.
38:37Because post-Black May of 1943, Allied convoys were crisscrossing the ocean relatively untouched.
38:45That all changed in September 1944, just off the north coast of Ireland.
38:51When a lone U-boat, fitted with the new snorkel device, wreaked a deadly havoc and rocked the confidence of the British High Command.
39:00We're diving on a wreck called the Empire Heritage.
39:02So the Empire Heritage, she was originally built as a factory ship, a whaling factory ship in South Africa.
39:07So she's known as the Tafelberg.
39:09So in the Second World War, these were really valuable because they were so versatile.
39:14The massive ship, one of the biggest sunk during the war, was making its tenth crossing off the Atlantic, carrying war supplies and sailors back to the UK.
39:24This is a huge ship.
39:36You know, you're coming down and the first thing they'll come up to you are the huge twin derricks, these mass coming up to nearly 40 metres.
39:48The ship isn't sitting up like you might classically imagine a ship like this, it's done that. And then everything is just slid off to one side.
40:00The Empire Heritage was loaded with 16,000 tons of fuel oil and a valuable cargo of Sherman tanks and trucks that were destined for the war in New York.
40:18The D-Day landings had taken place two months before, and the Allies were gradually pushing their way through France.
40:37It's one of those sites where I don't think it actually hits you until you've got out of the water and you watch the footage back and you see someone swimming next to a full-size Sherman tank.
40:55And they're just scattered in such random directions and positions.
41:01You know, it's not just the Sherman tanks, there's these 20-ton trucks.
41:06The cab is gone, but the chassis is there, the engine is there, double axle at the back, double tires on each axle, and the tires are still inflated.
41:14It's mind-blowing to think about how big that ship would have been to be carrying so many tanks and trucks, and then the destruction to then sink it.
41:25It's incredible, it's really quite an emotional process that I go through when you consider how these things get to lie on the seabed.
41:32After the Germans had lost their French bases, they had to transfer all boats from these bases to their new Norwegian bases.
41:43And the range of most of the Type 7 boats was not long enough to go into operations in the open Atlantic.
41:52So Dönitz had the idea to send all these snorkel-equipped boats into the coastal waters around Britain.
42:02One of those boats was U-482, commanded by Graf von Matuschka, a young commander on his very first patrol.
42:14Operating with the snorkel, he was able to hide undetected close to the Irish coast.
42:21In the week before he spotted the Empire heritage, he had already sunk three ships in the same area.
42:28Oftentimes, you know, individual initiative, the willingness to take risks, was an important mark of a successful U-boat commander.
42:37He was highly praised for the conduct of his operation because he went right into these heavily covered areas and he never made some second thoughts about being endangered.
42:50He just said, well, I'm going to attack and sooner or later I will escape.
42:54And as matters turned out, he was successful in this role.
43:01As the Empire heritage sank, U-482 lay in wait as a rescue ship, the Pinto, plucked survivors from the water.
43:11So she came alongside to try and pick up sailors in the water, and she too was torpedoed.
43:17She had about 60 people on board, of which 20 drowned.
43:24In total, 130 men lost their lives in the tragedy.
43:32The sinking of the Empire heritage and the Pinto was a stark reminder to the Allies that the battle was not yet won.
43:39The Nazis were determined to keep fighting until the bitter end.
43:44When I film shipwrecks that have had a loss of life on them, you have to be respectful for that, because that is literally somebody's grave.
43:51And in the same way, you wouldn't just carelessly walk through a graveyard standing on people's graves.
43:58In some respects, whilst we swim over these locations, we're kind of doing exactly that in a way.
44:03So you have to be mindful and respectful at the same time.
44:06There would have been shock and surprise at the fact that convoys are being attacked in coastal waters.
44:12That was not expected.
44:13But clearly, you know, in this case, a lot of bravery, but different tactics and clever tactics.
44:20The introduction of the snorkel proved that U-boats with advanced technology could still pose a significant threat.
44:33The Kriegsmariner were convinced that the new Electro-boat would be a game-changer in the Atlantic Theatre.
44:40By late 1944, hundreds of these new boats were being manufactured at shipyards across Germany.
44:48Designed in nine separate sections, the ultimate plan was to transport these sections to one location, Bunker Valentin, where they would be assembled, completed and launched.
44:59The idea of this bunker was to mass-produce these submarines on a kind of assembly line, and they would have worked on 12 boats at the same time.
45:13As far as you know, 6,000 people would have worked inside the bunker each shift, as you can imagine, because they needed so many of these boats so fast.
45:25Desperate to ramp up this modular mass-production model, the Nazis were pouring all available resources into finishing construction of the bunker.
45:34But just a few months from completion, the Allies were preparing to make their move.
45:39They had the means of air reconnaissance over almost all of Germany.
45:46And so they sooner or later detected that there was something going on at this site.
45:51And they realised that the Germans were building somewhat really, really great.
45:54On the ground at the bunker site, Harry Callan and the other Irish seamen were enduring ever more difficult conditions at the hands of brutal SS guards and a sadistic camp commander.
46:08It was pure terror. Every day was terror. The roll call in the morning where they'd have to stand in rows of five in the yard and be counted. And he would just pick on someone.
46:20One day he picked on a man and had him run backwards and forwards and backwards and forwards and pick shots at him. Until the poor man just dropped down to his knees and then he just shot him and killed him. For no reason.
46:33For no reason.
46:34The Estapo, they were judge, jury and executioner. If you did anything wrong, they didn't like them. They just pulled their gun out and shot him.
46:49The threat of death was constant for the thousands of men continuing the construction work. And as the bunker neared completion, it was thought to be impenetrable to attack.
46:59The final idea was to bring all walls and the whole roof up to seven meters of concrete. The minister for propaganda, Joseph Goebbels, visited the construction site in November 44.
47:14And he said, OK, the works are so far that no Allied bomb can do any harm to this project.
47:23The Allies knew they couldn't risk allowing the bunker to be finished and these advanced weapons to make it out into the Atlantic.
47:30They made very clear photographs of the site. What they were interested in was how far is the projection of the roof. Because on one side of the bunker, the roof is seven meters. But on this side, it's only, it's only 460.
47:52Just months after Goebbels made his bold claim, two RAF planes from 617 Squadron, known for their Dambusters mission two years earlier, launched a daring raid on the site.
48:05One attack, two bombs, this one and one at the back. That was the end of all works on this construction site.
48:16After 24 months of building, Grand Admiral Donitz's dream of unleashing a wave of technologically superior U-boats was no more.
48:33Thousands of prisoners died in the Bremen Fargar camps, including five Irishmen. One of the oldest of the group, 58-year-old Patrick Breen, was beaten to death by the guards.
48:53He was in the camp on his own most of the time, because he wasn't physically able to work. And they came back one day, they found him outside the barracks beaten up. And he was dead.
49:10Harry and his fellow Irishmen were the longest serving prisoners in the camp. 27 of them managed to survive.
49:18In March 1945, they were still being held captive. But things were moving quickly, and freedom was close.
49:31With the loss of the bunker, and no prospect of assembling the much vaunted electro-boat in the numbers needed, the U-boat campaign in the Atlantic was doomed to fail.
49:41But the Nazi high command were determined to fight on, no matter the cost.
49:46At the end of the war, the German U-boat arm was mostly made up of reserve officers. All of them lacked the essentials in training.
49:56And this is one of the reasons why the loss figures in the year 1945 rose to figures unheard before.
50:03So there were months when there were 60% of the boats sent out did not return.
50:10The convoy comes through, the supplies reach Britain, but one more U-boat goes to the bottom.
50:17At the end of March 1945, even German U-boat command realized that these kind of figures could not be tolerated anymore.
50:24On 30th of April 1945, Hitler died by suicide in Berlin. He was succeeded by the head of the German Navy, Grand Admiral Karl Dunitz.
50:36Just days later, the man who had masterminded the overall U-boat strategy in the Atlantic, and who had now lost his two sons in the battle, ordered his men to surrender.
50:48He said, well, six years of fighting are over now, and you have still to continue and to obey orders.
50:55They had to surface, they had to show a black flag as a sign for surrender, and then they had to steer for certain harbours and places that had been named by the British.
51:10When they intercepted the signal that Donuts sent on the 4th of May 1945, he told his submariners that they finished this war undefeated.
51:23This happened at the end of the last war, that the Germans were convinced that they weren't defeated.
51:29If any part of the German forces believes that it wasn't defeated, then we could have the same trouble again.
51:36Admiral Sir Max Wharton was taking no chances, and he decided that the entire remaining U-boat fleet would officially surrender in a formal ceremony.
51:50And he decided that the most important base in the Battle of the Atlantic had been on the River Foil.
51:56They would surrender at Lysa Halley on the 14th of May 1945.
52:00They came some way up the River Foil, a great day for all who saw them, and by no means least for Admiral Sir Max Horton commanding the Western approaches.
52:12Though a number of German U-boats had not yet been accounted for, this was really the end, at last, of one of the most bitter and dangerous struggles of the whole war.
52:21Time and time again, the very issue of the war depended on the breaking of the U-boat blockade.
52:25As British Admiralty debated what to do with the surrendered U-boats, the young German submariners were kept as prisoners of war, close to where a young Bert Worski lived.
52:36There's a prisoner of war camp now, where we're standing now, where we're standing now, where those pilings are, that was where the prisoner of war camp was.
52:48You know, when you looked at them, they were young lads. There were very few of them in their thirties. You know, they were all young fellas.
53:00They worked in the submarines during the day, empty in the submarines, and they marched down at night, and the Germans didn't march without singing.
53:09It was so exciting, us marching along with them. And one of the officers threw me a cap, and I don't have that cap that day.
53:19In the six months the Germans were kept prisoner, they worked to strip their boats of all materials on board.
53:26There was a wee manager railway line, come right down to behind our houses nearly. And when they were empty in the U-boats, they brought the stuff down, you know.
53:36So us as a crowd of young fellas, we were going through what was on the things, you know. We weren't stealing anything, we were borrowing it, you know.
53:45I would say everybody at Lyssa Halley had a German blanket.
53:53In effect, these boats were a source of technical features, and then it was investigated in very great detail if there were any technical inventions that could be made use of in the Royal Navy or in the US Navy.
54:09German U-boat design and technology would form the basis of the next generation of submarine in navies of America, Britain and Russia.
54:18But for the boats tied up in Derry, their time was up.
54:23The U-boats had been collected into Loch Foyle and into Loch Ryan in Scotland, and it basically was a question of what do we do with all of this?
54:32And so the plan was developed to sink, scuttle these boats in a big operation.
54:45Operation Deadlight in November 1945 is designed to remove, once and for all, remove the U-boats as a threat against Great Britain and her allies.
54:53So all of the boats, and there were about 60, tied up at Lyssa Halley along the River Foyle, were towed out into the Atlantic.
55:03Quite a few of them actually broke the toes and sank themselves.
55:08Others were shot up by destroyers or other warships, and some by aircraft firing rockets at them.
55:17And basically, apart from a few U-boats, all of them went to the bottom of the sea.
55:30A lot of convoys had gone out over the northern tip of Ireland, and they had gone from or past Derry.
55:35So this is a significant place to scuttle these U-boats, and there's something almost poetic about it.
55:42There was no escape like it had been in the First World War. At the end of the Second World War, the U-boats arm was utterly defeated.
55:50These sunken relics, whether scuttled in a symbolic act of victory, or condemned to the depths by enemy torpedoes, remind us of the all-too-human cost of war.
56:16During six years of intense fighting at sea, over 100,000 people lost their lives.
56:29Grand Admiral Karl Donitz was tried at Nuremberg and served ten years in prison.
56:34He was released in 1956 and lived a quiet life in rural Germany.
56:39He remained unrepentant right up until his death in 1980.
56:46But the battle, and its aftermath, lives on in the minds of people who are still trying to make sense of it all.
56:53People like David Brew, who has spent a lifetime searching for traces of the father he never knew.
56:59And Bert Worski, the Lissahalli boy who bore witness to the historic events taking place on his doorstep.
57:08For others, treasured family archives hold precious memories of their loved ones' honoured service.
57:18Like the young navigator, Hugo Yellamar, and his wife Mary Arem, who met during war and lived a long and happy life together.
57:29And of Evelyn Chavasse, whose memoirs revealed a faith which sustained him through the darkest months of battle.
57:40He gave up his navy career to become a Church of England minister.
57:44For those who survived the worst of conditions, life went on.
57:53Young Harry Callan finally made it home to his family in Derry, four and a half years after being taken prisoner.
58:02Despite everything, he returned to sea.
58:07So, he actually filled out this piece of paper, the period between 1940 and 1945.
58:13I was a prisoner of war in Germany, and he signed it, Harry Callan.
58:17And he would just hand that to the captain.
58:19And the captain would say, oh, okay, right, fine.
58:23No questions asked.
58:25No questions asked.