Original subtitles

Tom ward (narrates): An extraordinary dam

on a Welsh hillside.

It's hard to believe that something could have taken out

that whole middle section.

On the west coast of america,

a deceptively peaceful gateway to hell.

This was a real contrast

to what many of them knew was to come.

In Belarus,

a defensive structure that had a huge impact

on European history...

Were it not for the small but mighty fortress,

a lot more Europeans might be speaking French today.

..And a baffling ancient wonder in Mexico.

You have all of these massive arches

that really just dominate the landscape.

Decaying relics.

Shadows of lost worlds.

Ruins haunted by the past,

their secrets waiting to be revealed.

In San Francisco bay,

a cluster of relics sit marooned on a hilly island.

You'll come across

what looked like defensive structures

and you'll see in some areas there were gun emplacements.

Clearly this was a place with, you know,

great military or naval significance.

But when was it used and who was it working against?

Elsewhere,

an assortment of bucolic structures conceal a dark history.

There are some that look like quaint little houses,

it almost looks like a little holiday village.

It's like a retreat or something place

that you would go to rest and relax

but it's completely empty, completely deserted.

Who lived in these pretty houses?

And what conflict shattered their lives?

On angel island,

ranger Casey Dexter-Lee enjoys sifting

through layers of history.

One of the nice things about exploring around angel island

is even someone like me

who's lived and worked here for 20 years,

I'm still discovering new things

even buildings I've been in before,

there's details that you'll notice when you return

that really, you know, get you excited.

The ruins here date back to the 19th century.

With the beginning of the civil war in 1861

public concern over the lack of the defences

in the San Francisco bay continued to mount.

This is camp Reynolds,

a Garrison for up to 700 men

and the first to be built on angel island.

Camp Reynolds was built in 1863

to help as defence during the American civil war,

to protect San Francisco from attack from the confederacy.

At first,

angel island seemed like

one of the us army's most desirable postings.

First room here is the library

and it's connected by these archways into the parlour,

there was also a large room over here

where gatherings would have taken place

and there's a large brick fireplace in there.

Overall this place looks like a paradise for a soldier.

In 1864 there was an inspection

and one of the people in that group was Mark twain,

and he wrote about camp Reynolds

calling it a pleasant little village.

I can see that little village that Mark twain was talking about

but this place has a darker side.

As it turns out,

soldiers posted here were sent off to some pretty awful combat.

When the American civil war ended in 1865,

the soldiers stationed on angel island

were looking forward to some well earned rest.

But before long,

they were facing the grim prospect of yet another war.

As Americans were pushing further west

and towards the pacific,

these tensions between Americans and native Americans grew violent

and this is known as the Indian wars.

Native American attacks on white settlers

who had encroached on their lands were common.

By the 1870s,

the us government had forced them into reservations.

And the native people say enough and start fighting back.

It was only a matter of time

before the two us army companies on angel island were sent

to keep the peace.

If you were a soldier sent to angel island

there was a pretty high probability that you were going to be sent

to fight these warring tribes in the west.

And the troops here you know, scouted,

provided guards and escorts

and generally patrolled the American west

during this tumultuous period,

they would be sent wherever they were needed,

wherever there was an outbreak of fighting

in the Indian wars.

The men of camp Reynolds

usually had a nervous wait for the enemy

to show themselves.

These battles were fought viciously without quarter,

so there would have been high anxiety among troops here

wondering where they would be deployed

and against who.

Over in Oregon,

rebels from the modark tribe

were refusing to stay on a reservation

far from their ancestral lands.

They were led by a warrior named kintapuse

known to the white settlers as captain Jack.

Captain Jack ended up fleeing the reservation

that the us government had placed them in

and they instead demanded to be reserved on their own land.

Captain Jack wanted to return home

to lands the modark had inhabited for 14,000 years.

The us cavalry

and a company of infantry from angel island

were sent to defeat them in battle

and drive them back to the reservation.

Angel island was the western most outpost

of the us army

and the nearest Garrison to the modark wars.

They would leave the island by steamer,

they'd be dropped at a rail head,

they'd be sent in to the interior of the country

or up a trail into Oregon territory.

By January 1873,

captain Jack was holed up with fewer than 60 warriors

in an area of inhospitable terrain called the lava beds.

The us army were closing in.

The us troops were approaching

what they thought was flat land

and what they didn't know was that the modark people

were hidden away in a stronghold,

us troops expected a quick modark surrender,

but that is not what happened.

You have this great battle

where the American soldiers believe

they're going to have an easy go of it,

in reality, it's very rugged terrain,

it's foggy, it's cold, the Americans just get confused.

They're being attacked

from all sides and they finally retreat,

and this is a great victory for the modark people.

The American troops withdrew to camp Reynolds.

They would be returned to the island

for rest and relaxation

and to be reformed in

to another unit for another operation.

But as the soldiers on angel island knew all too well

the war was far from over.

The modarks would not go down without a fight.

Back on the mainland,

president Grant had decided on a different way

of dealing with captain Jack.

He sent a peace commission, one us general,

a clergyman to parley with captain Jack

and captain Jack, you know, welcomed the peace commission,

parlied with him,

was getting nowhere with his demands,

so he killed the two commissioners.

Though captain Jack had hoped

that killing these two peace negotiators

would push the Americans to back off,

it had the exact opposite effect,

the American troops come down hard on the modark people.

This provoked a violent reaction from Grant,

he sent cavalry troops

plus the 12th regiment from angel island

and they pursued captain Jack,

cornered them, fought a battle, defeated them.

After their capture,

captain Jack and three others were hanged for their crimes.

Other comrades of the captain faced similarly gruesome fates.

The two men who were captured with captain Jack

died in prison and eventually were buried on angel island.

The cemetery at camp Reynolds is no longer here,

when the army left,

they removed everyone from the cemetery.

The modark war is thought to be

the costliest of all the so called Indian wars.

Both companies from angel island

suffered heavy casualties in the modark war.

The casualties included 53 us soldiers,

17 civilians,

15 modark warriors

of whom only 5 of which died in battle?

Following the war,

most of the modark people were relocated to Oklahoma.

During the 1890s,

angel island reinvented itself completely

as a line of defence against an invisible enemy.

A us quarantine station on angel island

was built in the 1890s

to help protect San Francisco from illness

that might be bought in to the area by ships

coming from all over the world.

The buildings were kind of spread out

so that they could segregate people

based on illness, class, race, sex.

And the whole idea behind the quarantine station

is that the ship itself would be isolated, fumigated,

the immigrants and crew aboard the ship would be taken off

and put into the quarantine station

where they would be isolated for 14 days.

With the advance of medicine,

the quarantine station gradually became obsolete.

The world war has bought a final burst of life

and new construction to the island

before the army finally moved away for good.

Angel island is now a California state park

and historical landmark

and as the largest natural island in San Francisco bay

it's become popular with hikers.

You've got the space that was once for soldiers,

now it's being used by families

and enjoyed by people from all across the state

and all across the country.

On the central Mexican plateau

is an engineering masterpiece

that once bought life to this arid land.

There's this stunning bridge like structure

that rises over the earth and then disappears at the ends.

It looks like a railroad bridge,

but for some kind on miniature train,

it's only a couple of feet wide.

The architectural style suggests the vision

for this classical looking ruin was conceived on foreign shores.

When you get close,

you see that first of all it's very old

and it seems to be built like something

that the romans might have built

or that might have been built in renaissance Italy.

Nearby are more stone structures

and a religious looking building that don't seem to be connected.

You've got a series of tanks and pools

scattered around the place

and then you have what looks like an abandoned chapel.

But how is everything here linked

to the massive stone monument

and the surrounding desert landscape?

There must have been a good reason for engaging

in such an extraordinary act of construction

right here at this remote spot.

The idea for this unusual piece of engineering

came from a surprising source.

Raul macul Martinez is an archaeologist

at the Mexican ministry of culture.

He spent years sifting through the desert sands

to understand how these structures were built.

(Speaks Spanish)

The history of the otomba region is stained in blood,

spilt by fighting foreign invaders.

In the early 16th century Spanish conquistadores

began a campaign against the aztec empire here

in this region of Central America.

Once the aztec empire had been vanquished,

a period of brutal Spanish occupation began,

and there seemed little anyone could do

to unite this troubled land.

(Speaks Spanish)

Key to Spanish culture was their religion.

Everywhere they went,

they would bring these catholic friars

who would set up missions

and try to convert the native peoples to catholicism.

The conquistadores also created havoc

on the local terrain.

The introduction of European farming methods

like cattle grazing took a devastating toll

on the limited supply of clean water.

If there's one element

that defines otomba and the surrounding regions,

it's a scarcity of rivers and fresh water.

(Speaks Spanish)

In the mid-1500s,

a Spanish priest called father tembleque

came to otumba with a solution.

Father tembleque was an expert in hydraulic theory,

the construction of a new and highly elaborate aqueduct

was meant to supply otomba

its residents and surrounding region

with the fresh water that they needed.

Named after the catholic clergymen

who inspired its creation,

this is the aqueduct of padre tembleque.

(Speaks Spanish)

Some of the people around him

did not have faith in tembleque's ideas

and they called him fraile loco de la nada

or crazy friar of nothing.

(Speaks Spanish)

For this ambitious project to succeed,

father tembleque needed the help of the indigenous people.

But he had to convince sceptical tribal chiefs

that a reliable source of drinking water

was good news for everyone.

(Speaks Spanish)

But the Spanish were desperately in need of local knowledge.

In Europe, when people built large stone structures,

whether it was a cathedral or an aqueduct,

they would build an elaborate wooden

scaffolding around it as they built it.

But out there in the desert,

you didn't have sources of timber

and working with wood

was not something

these local artisans really knew how to do.

But if you actually look at this structure,

we can get some clues

of how they worked around this issue.

So, they came up with a brilliant idea

which was to build in essence

a structure out of adobe

that would rise up as they built the stones,

support the stones

until they got everything put together

and then they could take the adobe away

and you'd have this beautiful self-supporting stone structure.

Construction began in 1555

and continued for 17 years.

While Roman ingenuity inspired the aqueduct's design,

it was home-grown expertise that got the job done.

(Speaks Spanish)

Another clue to the idea

that these local artisans

were really invested in this project was the decorations they did,

the little paintings, the little insignia,

little markings on the rocks.

(Speaks Spanish)

It seemed to say we're taking some pride in this

and I wanna put my John hancock on this arch that I built

because it's a big deal.

The building of this waterway

would not have been possible

were it not for the indigenous people

and their knowledge.

When complete,

the entire canal system stretched for 30 miles.

The channel carrying water was only about a foot across,

but if that channel's full of water all day and all night

that's a lot of water,

now they had a system

that distributed water all year round.

And for the next few centuries,

water continued to flow

along this engineering marvel

that had been inspired by ancient technology.

But over time,

the mountain spring that supplied it began to dry up

and new sources of water had to be found.

(Speaks Spanish)

The monument stands

as an enduring reminder of the clash between two worlds.

What remains today is this fusion

of two distinct cultures and ideas,

you have this mezzo American knowledge of construction

with this Roman hydraulics,

and the two exist together in this aqueduct.

(Speaks Spanish)

On a remote hillside in wales,

a collection of stone relics have somehow survived the centuries.

Looking around in the valley,

you see a lot of these old, old structures.

There are homes here, as well as signs of industry.

As we make our way up this valley,

we see these two strange thick walls.

And it looks a bit higgledy piggledy

but it's definitely been placed there deliberately.

The whole middle section of the wall is completely missing

and through the gap flows a small little river.

What catastrophe could have caused

this well built wall to collapse?

If there's a failure in either the masonry structure

or an explosive failure,

then you're basically sitting on a bomb of energy.

As the pieces of this stone Jigsaw come together

a historically significant picture begins to emerge.

This valley was pivotal

to British history for several reasons.

David James' family

has lived in the elan valley for generations.

He knows how to read the clues here.

So, we're walking towards the entrance

of the mine shaft.

There was metal work here

to lift the lead ore out of the mine.

So, lead is one of those wonder materials

and wales is very, very lucky,

it sits on some of the world's best lead supplies.

Originally you would have had a big, big opening here,

nice big square open,

opening with a timber frame around it

and just went a long way down

240ft eventually with levels going off.

Lead has been mined here for thousands of years.

The romans mined in the area as well

going back 1,000bc

where they mined lead

in which they mainly made water pipes,

ornaments, and coffins from.

Over the millennia,

extensive infrastructure gradually developed.

So, we're walking now towards one of the two water wheels

that was built at the mine here.

The waterwheel was basically like an engine if you like.

By the 18th and 19th century

britain becomes the centre of lead mining in Europe.

The elan valley became a hive of industry,

as people flocked to work here.

Working men came from all over the valley

and walked many miles to work here.

The miners lodged

in the different cottages and farms

spread throughout the elan valley here.

You would have had whole families that, you know,

clustered around these lead pits.

But there are also some seemingly unrelated structures hidden here.

You've got bricks inside and outside

and then a concrete reinforced concrete in between.

The walls are roughly about 1.5ft thick.

They're leftovers from the second world war,

all they're designed to do is hold a man,

a gun and defend an area that he can see directly from it.

They line up one after the other

and you create a wall of fortification.

In here you have the window for the marksmen

to point their guns out of.

These gun ports face down the valley

toward a series of lakes

which have been manmade but for no apparent reason.

But directly downstream from elan valley

is the city of Birmingham and its vast industrial hinterland.

In the late 19th century

Birmingham needed a better source of fresh water

as their population grew.

They constructed a series of dams to impound the water in this valley.

It took almost 10 years to lay 73 miles of underground pipe,

build four dams and flood 850 acres of the elan valley

submerging a manor house and a lead miners' village.

By the time of the second world war

water from the Welsh valleys

had helped Birmingham grow in to a centre of ordnance,

armaments and vehicle manufacture.

The British were worried

that the Germans might try to attack and take out these dams.

This was German planning for operation sealion,

their eventual take-over of the British isles

and so the British were on guard

against attacks on key infrastructure.

The overgrown fortifications were built to guard

Birmingham's crucial water supply.

But one dam has been blasted apart.

So, what we had here was a nant-y-gro dam,

it was a structured across the nant-y-gro stream here

as 35ft high and full of water

and as you can see

the middle section of the dam was completely blown away.

By the start of the war,

the nant-y-gro dam had become redundant.

The nant-y-gro dam

was a substantial structure in its time,

originally built for the workers living in the area,

but times had moved on and it wasn't needed anymore.

But with the onset of war

the out of use dam came in to its own

when it attracted the attention of the British inventor

and aeronautical engineer Barnes Wallace.

Barnes Wallace began thinking

about what it was going to take to damage German infrastructure.

The British knew there were a number of dams

on Germany's rue river

if they could knock out one, two, three of these dams,

it could set the Germans back months or years.

So, Barnes was starting from scratch here,

how could he take out a huge dam

behind enemy lines?

No existing aircraft was capable

of carrying a bomb big enough to blast the dams from the air...

So Barnes Wallace started by experimenting

with naval torpedoes.

But the Germans had already thought of this

and they had assembled

an array of underwater nets

to protect these dams from just this risk.

Wallace had to find a way

to blow up the dams using smaller bombs.

He needs to find a place in the UK

where he can try out this dam busting concept.

And that's where the nant-y-gro dam came in.

It's only a fifth of the size of the dams

that they were aiming for in Germany,

but if they could get it to work on this one

there was a good chance

that if they scaled it up, it would work behind enemy lines.

But the nant-y-gro dam wasn't that easy to destroy.

The first experiment was done in may 1942

and even though it's spectacular,

it didn't cause much damage to the dam.

It goes off successfully

but barely dents the dam structure itself,

they need to think bigger.

They come back in July 1942 with a bigger bomb,

a 279 pound explosive,

dangled it from the centre of the dam

under the water

and remotely detonated it, and boom.

It blew a hole in the dam you see today,

60ft wide the hole is

and if you come through here,

what we have here is the remains

of the other side of the dam

and if you look down here is the bottom of the dam

what's left and the rest was blown away.

This experiment proved

that if you could get a big enough explosion,

just below the water line,

you could blow the masonry apart

and then use

the pressure of the water built up behind the dam,

use all of that energy to tear apart the structure itself.

You're on to a winner.

Now, they have to figure out the tactics of skipping that bomb

up against the wall of the dam.

Wallace thought,

"what if I can build a bomb

"that could bounce along the top of the water,

"over the nets the Germans had assembled

"to protect their dams?"

After the nant-y-gro trials,

the bouncing bomb was successfully tested

on other British reservoirs.

And in may 1943,

Barnes Wallace's invention

successfully destroyed two German dams,

marking a major turning point for the allies

in the second world war.

Back at the broken dam in wales,

enthusiasts like David continue to unearth secrets.

I absolutely love the history of the elan valley.

It goes back as far back as the bronze age

and is still making history today.

On the flat lands of central Belarus

sits a small collection of ruins with a big history.

All across the site,

there's a real hodge-podge of different types of buildings

from different periods, some ancient,

some more modern.

Ceilings have caved in, walls have collapsed,

and the greenery and grass look like

they're almost swallowing the structures up.

Spanning just 100 acres,

the secret's here are cleverly concealed.

It's not all about the surface,

underneath there's lots and lots of tunnels,

lots and lots of places to get lost.

These underground military structures help to shape

the destiny of Europe.

Were it not for the small but mighty fortress,

the situation might have turned out very differently,

a lot more Europeans might be speaking French today.

Local historian Sergei pshantsev

has been studying this place for many years.

(Speaks French)

This is the Babruysk fortress.

Its story is linked to one of the most infamous men

in European history.

Napoleon Bonaparte.

In early 19th century,

most of the European continent was under French rule

and the power of the mighty Napoleon Bonaparte.

Back then these ruins and the country of Belarus

were part of the Russian empire,

the sworn enemy of Napoleon and his allies.

Various plans were drawn up

for the defence of the Russian empire

and one suggested a series of fortresses

along the rivers on the western side of the empire.

Construction began in 1810,

a series of state-of-the-art strongholds

would block napoleons path in to Russia.

The town of Babruysk was critical to the defence of Moscow.

This was a key spot on the river,

a tactical advantage to create a fortification.

You could stop a huge number of people

moving from a to b in this particular spot.

The Russian tsar threw everything he had

at building a fortress to defend his empire

against a powerful enemy.

Napoleon didn't do things by halves,

he raised a massive, massive army,

a huge number of men

and started approaching the Russian border.

Using troops from all over his European territories,

he raised an army that's estimated

to have been between 450,000 and 650,000 soldiers,

this was the largest invasion force

that had ever been put together in European history.

With fewer than half Napoleon's troops,

the Russian commanders were facing almost certain defeat.

Napoleon expected a quick victory.

He thought he could push straight through

to the capture of Moscow the capital.

He was determined to get to Moscow

and meet the Russian army in open battle.

Napoleon Bonaparte was a scrapper,

he was a fighter, he was a, you know,

really wanted to get up close and punch the enemy

and he had thousands of troops behind him.

But this time,

Napoleon's daredevil tactics worked against him.

What he wasn't expecting was for the Russians to retreat.

With Napoleon hot on their heels,

the Russian army retreated more than 100 miles

heading for the safest place it knew.

The Babruysk fortress.

This was the only fortress on the route to Moscow

that had the infrastructure

that could hold out against a determined assault.

When the Russian troops made it to Babruysk,

they received a warm welcome.

They found medical supplies, they found food,

and they found a defensive safe place to stay.

When the French army finally reached Babruysk,

Napoleon was expecting to find the Russians lined up

for a glorious battle.

But all that remained

was a small Garrison of men cowering in the fort.

The clever design of the tsar's fortress meant

that even the great French leader was unable to conquer it.

(Speaks French)

If anyone steps into that zone,

they are risking getting

a huge, huge set of explosives sent their way.

The well planned kill zone

prevented Napoleon from taking the fort.

So, he left behind a detachment of 10,000 men

to lay siege and starve out the Russian troops

holed up inside.

But thanks to the ingenuity of the Babruysk planners,

the Russian Garrison

had one more trick up its sleeve to thwart Napoleon's plans.

(Speaks French)

During the siege,

they used the tunnels to sneak out

and spy on the army,

collecting vital intelligence

that could then be forwarded to the Russian army high command.

Meanwhile the Russian troops at Babruysk continued to hold out.

Napoleon drove his exhausted men on towards Moscow

expecting to find the Russian army there.

When they arrived,

they were met by an extraordinary sight.

When Napoleon's depleted grande armee finally reach Moscow.

To their utter disbelief,

they find it abandoned and scorched to the ground as well.

The Russians had already left,

they'd already moved out,

they were not going to engage in the fight,

and Napoleon and his already stretched, depleted,

unhappy troops found an empty city.

With winter approaching and food supplies dwindling,

Napoleon had no choice but to retreat.

But there was one big problem blocking his path home.

Babruysk fortress had still not fallen.

(Speaks foreign language)

The fortress was never taken.

For the great Napoleon Bonaparte, it was a calamitous humiliation.

The napoleonic invasion of Russia

is one of the greatest military disasters of all time.

And that is really the beginning of the end for Napoleon.

Within two years,

Napoleon is going to have to abdicate

and go into exile.

Today, the Babruysk fortress lies silent and crumbling.

(Speaks foreign language)

Captioned by ai-media ai-media. TV