Original subtitles

[gentle music]

- [Narrator] On the cold winter evening

of February 27th, 1943.

A team of nine Norwegian commandos

arrive at the Norsk Hydroelectric Plant.

[gentle music]

Their mission, sabotage the Nazi's heavy water production,

which is vital to Hitler and his Nazis

creating an atomic bomb.

[gentle music]

- Gunnerside is a story that shows the dedication

that people during the Second World War had to the cause.

- We weren't talking about a weapon off the ordinary sort.

This was something which was extraordinary.

This was something which would change

the direction of history.

- This is one of the most important

weapon production facilities

in the entirety of Nazi Germany.

- Germany, gaining access to this heavy water

or to the technology of the heavy water plant.

Would've been a disaster.

[bomb explodes] [upbeat music]

- [Narrator] In 1911 and Norway, they built the

Vemork Hydroelectric Plant which was a massive facility.

- Initially we know it's there as a fertilization factor

as a hydroelectric facility,

but the by-product of which heavy water,

has become the raison d'etre of the plant

and this scientific gold mine really,

for want of a better expression,

is of course, courtesy of the know how

of several Norwegian scientists.

- [Narrator] Scientists in the early 1930s

discovered that from Vemork's facilities,

by-product is heavy water,

a form of water with a unique atomic structure

and properties which can be used in the production

of nuclear power and weapons.

- It's really another route

to it instead of using graphite as a monitoring element

that involves deuterium oxide, or heavy water,

and the whole design

there is to control the process of fission

so that it doesn't go boom.

- Harnessing something that's potentially fatal

on a macro scale, with this heavy water,

being the catalyst for that,

this alternative isotope of hydrogen.

- Leif Tronstad, a Norwegian scientist,

is a celebrated scientist.

And he's the brilliant mind behind the idea

of the heavy water process.

- [Narrator] The head of Norsk Hydro enlist Tronstad,

to design a new building at the Vemork Plant

dedicated to producing heavy water on an industrial scale.

[gentle music]

Around the same time, a seismic shift in Europe

is about to happen.

As Germany elects a new leader.

[soldiers marching]

- Hitler assumes power in 1933.

[gentle music]

- [Narrator] Hitler's Nazi regime is brutal.

- Almost immediately, they begin to root out

any kind of opposition that they feel

is political or social.

[gentle music]

- [Narrator] As the grip of the regime tightens,

many scientists particularly Jewish,

flee the country to pursue their work

beyond the Nazi grasp.

[bomb explodes]

- Scientific minds when they leave a country,

it's often considered a brain drain.

So the country is losing, their brain

or their ability to innovate

or advance technology, science, research.

- Germany becomes inhospitable for so many scientists,

particularly these Jewish scientists

and somebody like Albert Einstein ,

does have to leave so that he can continue

to not only be a scientist, but just live his life.

[gentle music]

- [Narrator] Despite many bright minds fleeing the country,

those loyal to the Nazi regime

stay behind to continue their work.

A number of scientists working on the development

of nuclear energy make a revolutionary,

yet terrifying discovery that could give Hitler

the ultimate weapon.

But they were missing one key element.

[ gentle music]

Meanwhile, Tronstad designs that Vemork become a reality.

And with the new eight story plant complete,

the station now has a designated

heavy water production site.

French and German scientists express their interests

in obtaining large quantities

for their nuclear energy programs.

- Everyone who is in the region wants access to the water

because it's so necessary.

- Harnessing something that's potentially fatal

on a macro scale with this heavy water,

being the catalyst for that.

- [Narrator] Germany policies became increasingly hostile

towards Jews, homosexuals and disabled people

during the mid to late 1930s. Ideals of racial superiority

and ultra nationalism

start to become more and more prevalent

throughout the country.

- As early as 1935, it passed in Nuremberg Race Laws.

It prohibits interracial marriage and relationships.

It prohibits other non-Aryan races or groups of people

from holding jobs in the law and medicine and academia.

- [Narrator] In March of 1938,

the Nazis annex neighboring Austria,

an early sign of their true expansionist ambitions.

Later that year, German scientists Otto Hahn

and Fritz Strassmann make the breakthrough discovery

of nuclear vision at their laboratory in Berlin.

- These are the men who identify nuclear fission.

This reaction that demonstrates or shows the way forward

in terms of nuclear energy and what you need that for.

You need that for the creation of a bomb.

- Once they, they have that knowledge

of how to create the energy.

The next step in terms of, using it is actually very quick.

- [Narrator] News about the nuclear experiments in Germany

travels quickly across Europe,

French Nobel prize, winning scientist.

Frederic Joliot-Curie writes a letter to a Soviet colleague,

alerting him of the Germans discovery.

[gentle music]

The news also reaches Neil's bore,

a leading danger scientist.

Who's preparing to leave on a trip to the United States.

[gentle music]

Once arriving in New York city,

he shares this news with prominent American scientists

sparking the beginning

of the American nuclear energy program.

[gentle music]

- Since the news of what could be done with the heavy water,

had become common scientific knowledge.

Every intelligence agency was interested

and was actively perhaps pursuing some plan

of gaining access to that heavy water.

- [Narrator] Within the span of less than a year,

each major power begins to ramp up their nuclear research

and experiments recognizing the great potential

of harnessing nuclear energy.

[gentle music] [bomb explodes]

In September, 1939

not long after the race to harness nuclear energy,

Germany's expansionist ambitions enter their next phase.

- Hitler invades Poland and the ballgame begins.

Poland is the trigger.

A lot of people did not want to go to war

because they remembered the First World War.

But because Poland was invaded,

Britain, France, they have to fight back.

[gentle music]

- [Narrator] As Europe descends into war

the Nazis continue their pursuit to harness nuclear energy

and develop a nuclear weapon.

[bomb explodes]

The French government recognizes

the importance of the heavy water

at the Vemork facility in Norway

and begin attempts to smuggle the heavy water out of Norway.

- The French recognize how important nuclear energy is

and how powerful it is.

So they of course don't want Germany to have access to it.

- So in an interesting collaboration,

prominent French scientists are working

with the French intelligence service

and trying to identify where a heavy water

is being produced and get it out of Norway.

- The French intelligence services

approaches Jacques Allier,

who before the war, worked at the bank that helped finance

the project to build the hydroelectric plant in Norway.

Because of his connections,

they assigned him the task of getting the heavy water

out of Norway.

But time was ticking.

- Norway is a country that has many

proud scientific advancements.

Norway's is an industrial innovator,

manufacturing innovator.

- Norway also was sort of a reservoir of natural resources.

- There's a huge number of reasons

why Norway is targeted really early on,

for a start it's got absolutely crucial pause.

It's Atlantic facing.

If you want to win the battle of the Atlantic,

you need access to their ports.

You also need access to their air fields.

So on the geographical front,

in terms of winning a strategic war,

across that Atlantic facing perimeter, you need Norway.

- All this makes it an even more compelling

target for Germany.

- [Narrator] French intelligence service member,

Jacques Allier,

flies to Norway with a fake passport and a fake name

to meet with the director of Norsk Hydro.

- They had enough foresight

to realize the Germans were held bent

on getting an atomic bomb.

So they were keen on getting the heavy water

out of the Norwegian Hydroelectric Plant

before the Nazi invasion.

- [Narrator] Once in Norway,

Allier secures all the heavy water, 180 kilos worth,

but he fears the Germans might be onto their plants

in order to avoid capture, Allier's books

two separate flights, one with the heavy water to Scotland

and another as a diversion to Amsterdam.

The Germans chose to force down the wrong plane.

- We've got the heavy water, all 180 kilograms

out of Norway and it's on the road.

It's moving, it's moving faster than Rommel's Panzers.

But the problem is, this is just a temporary setback

for the Germans.

- [Narrator] As the heavy water

is secretly smuggled into France,

the Nazis continue their invasion of Europe.

- Germany invaded Norway in the April of 1940.

- The conquest of Norway by Germany

tends to be seen as pretty rapid,

but it does take some time to happen.

And Norwegian resistance is the reason

why it does take some time.

- As thousands of German soldiers

are deployed across the country.

Norwegian put up a fierce fight.

Leading some of the resistance is Leif Tronstad.

The scientist who helped develop

the heavy water process at Vemork.

- [Narrator] Despite the efforts of Norwegians,

they cannot hold off the German advance.

[gentle music]

- Germany by June of 1940 is firmly in control of Norway,

including the hydroelectric plant.

[gentle music]

- [Narrator] Having quickly gained the upper hand,

the Germans continue their aggression

and launched their campaign against France.

Only one month after the invasion of Norway.

- Prime minister Daladier and his military advisors

think that they can hold any two front war,

which may come out of this push into Poland by Germany.

- The French retreat, both mentally and physically,

to the Maginot Line, which is this extended network

of fortifications along with Franco German frontier.

[gentle music]

- [Narrator] The French having underestimated their enemy

are overwhelmed by the onslaught of Germans

pouring into their country.

[gentle music] [soldiers marching]

- As the Germans begin their march to Paris,

Curie worries that the stolen heavy water

hidden in France will fall into the Nazi's hands.

[gentle music]

When it becomes clear that France cannot

hold off on the Germans, Joliot-Curie and Jacques Allier

decide to move the heavy water from France to England.

[gentle music]

- The problem of course, is France is overrun

at Paris is taken over by the Nazis.

[gentle music]

- [Narrator] Fortunately, Allier avoids Paris

and the heavy water is met at Bordeaux

by a British cargo ship, and is safely smuggled to England.

[gentle music]

Although both Norway and France

have now fallen to the Nazi regime,

the Norwegian scientist Leif Tronstad

is not ready to give up.

[gentle music]

- Before the Norwegian government flees for England,

before Tronstad the great scientist flees,

they establish a resistance movement

and an intelligence network around Norway.

So even though Tronstad and the king and others

are in exile in England, they have resources on the ground.

[gentle music]

- So Leif Tronstad knows a lot about

what's going on in the plant.

He has the ins and outs.

He's basically created an underground

spy network of his own, with him at the head

of this spy network.

He's keeping the British informed.

- So the Norwegian resistance,

monitoring what's happening at the plant is important.

One so that they know what's going on,

that they can keep track of what the Germans are doing,

but they can also report back to allies in other countries.

[gentle music]

- [Narrator] With his spy network,

Tronstad is able to provide British intelligence,

constant information on the Nazis activities at the plant.

[gentle music]

- In a war like the Second World War,

information is so key at all levels.

So the more information you have about

what the other side is doing, the better you can plan

and the better you can create your own strategies

moving forward for how you want to proceed.

- The Norwegian high command in England is very important

to the understanding of the resistance movement in Norway.

[gentle music]

- [Narrator] Once in exile Leif Tronstad

and the Norwegian high command

work closely with the British SOE known as

Special Operations Executive.

[gentle music]

- The special operations executive,

is basically counter intelligence,

insurgency inside of a foreign country.

They assist with resistance movements in country.

For example, Norway and France.

[gentle music]

- [Narrator] Having had to withdraw his troops from France

after the Nazis rapid invasion,

British prime minister, Winston Churchill

recognizes the potential of the SOE.

- For Winston Churchill, something like the SOE

is a great way to hit back at the Nazis

without having to worry about invasion at the time.

- [Narrator] Essentially functioning as an underground army,

the SOE is primarily made up of civilian volunteers.

One of the key groups in the SOE is known as Company Linge,

which consists of mainly Norwegians,

who fled to England after the German invasion of Norway.

[gentle music]

- Of course, people would volunteer.

Their nations had already capitulated.

There was no national army to join.

So to escape to London to fight some force,

to join some force, which would fight the Nazis

would be something which should be on the top of the mind

of many of these people.

[gentle music]

- [Narrator] As the Nazis tighten their grip

on the occupied nations of Europe,

the allies continue their nuclear research.

American scientists at the University of California

and Columbia University,

are working on various methods of harnessing nuclear power.

[gentle music]

Recognizing the potential and urgency in utilizing

this great new source of energy,

the British in 1941 released the MAUD report,

which contains plans for producing a nuclear bomb.

[gentle music]

- So there's a real rush for them to develop

a capacity, that's articulated by 1940

and the possibility of developing a uranium based weapon.

- American intelligence was now trying to beef up

and meet the threat that they now have

on what would become a two front war.

[bomb explodes]

- December, 1941, the Japanese attack Pearl Harbor,

and the Americans enter the war.

[bomb explodes]

- [Narrator] Only a month after the US is attacked

and officially enters the war,

President Franklin D. Roosevelt gives his a approval

to his science advisor

for the construction of an atomic bomb.

This marks the start of the Manhattan Project.

- So it only takes about a month, a little over a month

for Franklin Roosevelt to give the green light

on the Manhattan Project.

- [Narrator] By early 1942, it's clear to the allies

that the Nazis are hyper focused

on harnessing nuclear energy.

[ vehicles hooting]

- The Norwegian resistance and intelligence network

that Tronstad helps to develop,

they're providing regular updates to him

while he is in England.

One of the most disturbing is that Germany

has dedicated itself to ramping up

the production of heavy water in the hydroelectric plant.

[gentle music]

- The Germans start seriously focusing

on the production of not just heavy water.

They establish uranium club.

They're looking at all the different possible ways,

enriching uranium.

They're looking at the production of these isotopes.

They're looking at heavy water,

they are not closing down any options.

[gentle music]

- [Narrator] After receiving the concerning reports

coming out of Norway,

Leif Tronstad suggests a small targeted operation

to stop the Nazi's heavy water production.

His report lands on the desk of the British prime minister.

- Winston Churchill decides in 1942,

that Vemork is a key target.

It is where the heavy water is produced

for the atomic weapons.

- So the German operations at Vemork

are a threat to the allies.

There's no question about that.

- So the organization that really takes the lead

in trying to prevent Germany from getting the heavy water

and from trying to sabotage this hydroelectric plant,

is the SOE.

That's the Special Operations Executive.

- [Narrator] In the meantime, conditions in Norway

are getting worse.

In October, 1942, the Nazis begin

rounding up Jews in Norway.

More than a third of Norway's 2100 Jews

were deported to death camps during the war.

Tronstad and other Norwegian resistant members

are desperate to do something for their country.

- So yet another tragedy is the construction

of the concentration camps followed by

the mass construction of concentration camps.

There were a number of camps, Dachau, Auschwitz,

and others that had 10, 20 hundreds of satellite camps.

- By 1942, the complexion of the war was changing.

On the Eastern front, Hitler planned the invasion

of the Soviet Union,

an ambitious if ever there was one strategy.

Operation Barbarossa, but that would not work out.

[gentle music]

- [Narrator] In February, 1943

the Germans suffer a major defeat

on the Eastern Front at Stalingrad.

[suspenseful music]

With over a hundred thousand casualties,

this loss reveals that Germans are not invincible.

Although things looked bad on the Eastern front,

the Germans were getting closer to developing

a weapon that could change all that.

- They want more of it.

They want almost unlimited amounts of heavy water.

- They're bound and determined to get an atomic bomb.

- [Narrator] Recognizing the dangers

of allowing the Nazis production of heavy water to continue,

the allies are desperate to stop them.

Once planning for the attack on the Vemork Plant begins

Tronstad insists on a small targeted attack,

rather it than a bombing rate.

[bomb explodes]

- His greatest concern is that

the allies would simply bomb the area

and in doing so he pointed out importantly

that it probably wouldn't do the damage that you imagine.

- [Narrator] Despite Tronstad's insistence

on a small targeted attack,

he's overruled and British soldiers begin training

for a mission called Operation Freshmen.

- Now, how do you best eliminate a plant

that's hard to reach?

It's sitting at the bottom of an eight story

reinforced building.

It's surrounded by Norwegian civilians,

and as a bombing target is at best unlikely.

The thinking is, well, you'll send in

an elite task force with gliders.

[gentle music]

- Halifax bombers take off from England

and they're towing these horsa gliders.

- [Narrator] Throughout the war,

the allies successfully utilize gliders

on various commando operations

specifically for infiltrating behind enemy lines.

- Gliders are a various scary thing

when you're on the inside of them.

When the glider is pulled from its,

basically its tow plane, it is on its own.

- The problem is number one, it's a long flight to Norway.

Number two, the weather is horrible.

[gentle music]

And these gliders crash on impact.

[bomb explodes]

And kill some of the men on board.

The survivors are found by the Germans

and they are all killed.

- [Narrator] At that time, German soldiers had an order

to kill any enemies that were involved

with commando operations.

- So that means every SOE man is killed on this raid.

That means the gliders are ineffective against the axis

in that point.

And that also means the Germans understand

that Britain sees something in this plant.

- Preventing the Germans gaining access

to the heavy water was so important that a few setbacks

would not have deterred people.

Even losing the element of surprise,

now just means you to plan differently.

- [Narrator] After a disastrous first attempt,

the SOE turns to Leif Tronstad and Company Linge

to lead the next attack.

This mission is given the name Operation Gunnerside.

- Tronstad is the perfect person to try to disrupt

the plans and be more, he knows it better than anybody else.

He is the one who you would want to be in charge

of this operation.

He knows exactly what the plant is capable of,

but he also knows every nook and cranny of the space.

So he can best come up with a plan to disrupt

what the Germans are trying to do.

- [Narrator] To pull off this daring mission, Leif Tronstad

handpicks a small team of Norwegian patriots,

who like him fled to England

after the Nazi occupation of Norway.

The Gunnerside team is led by 23 year old Joachim Ronneberg.

He's joined by Claus Helberg, a 24 year old

who had grown up in the area around Vemork

and worked as a tour guide in the surrounding mountains

prior to the war.

As well as Knut Haukelid, Fredrik Kayser, Birger Stromsheim

and other members of the explosives team.

- They are not formally military trained men.

They're even better than that.

They're a hybrid.

They are physically fit.

They are young and they have extraordinary powers

of motivation, because they are local

and this is their patch.

They want to protect it.

- And they are trying to fight back against the Nazis

for their country, where this takes place.

That makes it even more personal.

- [Narrator] Having an intimate knowledge

of the Vemork facility.

Tronstad proposes that the team

target the heavy water cylinders

located in the plant's basement.

- Tronstad knows the hydroelectric plant.

So if the French, if the British, if the Americans,

if the allies are trying to get into

and sabotage this plant, Tronstad becomes invaluable.

- [Narrator] Tronstad suggests they blow up

the heavy water cylinders

with explosives to ensure they halt

the Nazis heavy water production.

The team will then escape to Sweden.

- If you want precision,

you have to have precise information.

This kind of information could only be provided

through reconnaissance photos.

- You need highly skilled intelligence

to understand the way in the way out

and where things are located inside the building.

- [Narrator] The documents provided by Norwegian resistance

at Vemork, reveal that 18 cylinders need to be destroyed.

With the massive increase in heavy water production,

each one of these cylinders will be filled to the brim.

- Every one of the cylinders housing

this water needs to be taken out.

- Therefore the commanders have to go

through some rigorous training.

They're practicing forging rivers,

they're practicing mountain climbing,

they're camping, they're hiking.

The physical fitness requirements are extraordinary.

- They do reconnaissance in the woods.

They do code and cipher.

They're taught how to read each other's communications.

They're taught how to use guns, how to use metal cutters.

They are taught how to climb rock faces.

They already know how to ski. In many respects,

they are, if you like your Renaissance fighters,

because they don't just hold a gun

and do close combat fighting, but they have, what's up here.

Knowledge of the local area

and ability to outsmart the enemy.

- [Narrator] Before the official operation begins,

a few of the Gunnerside team members

are sent to the Norwegian mountain wilderness

surrounding Vemork to survey and prepare for the attack.

- The whole mission kicks off on February 16th, 1943

as six Norwegian parachute onto Norwegian countryside.

- Time is of the essence, with every passing day

the Germans are ramping up

and producing more and more heavy water.

- [Narrator] The operation Gunnerside team

parachute into the Telemark region of Norway,

into an area far away from any German patrol points.

[dogs barking]

Their first task is to rendezvous with their teammates

who arrived months earlier

and are waiting for them in a cabin.

- So these men who just parachute into Norway,

have to traverse 60 kilometers of land to get to the cabin.

This is nothing easy.

This is not like taking a walk in the park.

- [Narrator] The cabin where the Gunnerside team

will begin their mission,

is located on the Hardangervidda plateau.

Legends say that this mountain plateau grows so cold

that it freezes flames in a fire.

- Most of the hardship was up on the plateau,

getting there, where there really weren't any options,

where the blizzard locked them in.

What else were they going to do?

[gentle music]

- [Narrator] At this stage of the mission,

the most important equipment they have are skis.

- Skiing is synonymous with Norway.

If there were non-skiers on that team,

they would've perished.

- [Narrator] Once the team arrives at the a cabin,

they're hit with a massive blizzard

- Landing in the middle of a blizzard,

you have to shelter in place.

Because if you go out into the snow in a blizzard

and you don't have really any way finding markers,

it is a death trap.

- [Narrator] The bad weather is a delay,

they could do without.

The clock is ticking.

[gentle music]

Meanwhile, across the Atlantic,

the Americans continue with their nuclear research

at an unprecedented pace.

- The Americans have multiple facilities, secret

and semi-secret facilities around the country

to develop this from a big processing plant

for uranium and the mountains of Tennessee

to the University of Chicago,

where some of the world's greatest physicists

were gathering to work on the next steps

in developing an atomic bomb.

- With Manhattan successfully underway,

the Americans and the British become increasingly convinced

that they'll be the first to develop a military capacity,

a bomb for this.

And that's exactly what happens.

[bomb explodes]

- [Narrator] The allies have no idea how close the Germans

are to developing their own atomic bomb.

So it's essential for operation Gunnerside to be a success.

After holding up in the cabin for a week,

the weather clears and the Gunnerside team

begin their journey.

- We hear about raids in the modern era,

going in and finding a target,

maybe being there on the ground

for two to four hours, and then being extracted.

This raid takes well over a week.

- [Narrator] During their training with the SOE,

the Gunnerside team was shown diagrams

and life size replicas of the heavy water cylinders.

They decide the best way to destroy them

are with plastic explosives.

- So the use of plastic explosives allows them

to carry it throughout this whole operation,

making the entire thing easier,

because they are lighter, they're more portable.

- [Narrator] These explosives also allow for precise

and targeted explosion to take place,

avoiding unnecessary damage or harm

to civilians and workers at the plant.

Something that was essential to Tronstad and his team.

[gentle music]

- Tronstad doesn't want an air raid,

he doesn't want anything that will create

mass destruction to Norway.

He understands that if you send in ground troops,

where you do mass air raids in Norway,

that it's going to take years and probably decades

to recover from that.

[gentle music]

- [Narrator] During their 40 mile journey to Vemork,

the Gunnerside team skis by day and rests by night.

[gentle music]

They finally reached the gorge near the waterfall

located just south of the Vemork heavy water plant.

- That would be an intimidating thing to see,

when you to the plant you see the waterfall,

you finally are back there.

It would've been an overwhelming moment I imagine.

- And in front of the factory is a massive ravine,

a huge gorge with a bridge leading over

it into the hydroelectric plant.

The bridge is guarded, heavy security,

which means you either have to scale down this mountain

or you have to forge a deep ravine, crossing an icy waterway

and climb back up to get in,

all the while it's surrounded by barbed wire, lights,

guards, mines.

So getting into this hydroelectric plant

is not going to be an easy task.

- [Narrator] During their occupation of Norway,

the Germans stationed hundreds of thousands of troops

in the country, one soldier for every eight Norwegians.

- The reality of the occupation once it's starts

becoming apparent is already too much

for people to bear.

- [Narrator] The occupation brings

severe economic hardships to Norway.

Food and other basic commodities become scarce,

and the country faces a real risk of famine.

The Gunnerside team waits patiently

outside of the Vemork Plant observing the German guards.

They know that crossing the heavily guarded bridge

is impossible and have figured out an alternative way

of getting inside the plant.

- There is one place that they can go in

and they can find their way in

and it leads right to the plant.

And that is the railroad line.

[gentle music]

- [Narrator] Realizing this would be their only way in

via the railroad line.

Ronneberg leads the team down into the frozen gorge.

[gentle music]

- The valley is very windswept.

You can imagine when you walk between buildings

and it's really windy, that wind forces through there

harder than if you're on the other side of the building.

It's the same with this valley.

That is a very dangerous place to be.

- It's a 600 foot gorge, down to the Maåna River below,

by the way, this is the bleak midwinter,

freezing conditions, ice, snow, and a field.[laughs]

Not even pretty in summer by the way,

that you would have to negotiate.

- [Narrator] But once the men have successfully

climbed down the gorge, the river presents a new challenge.

[water whooshing]

- You have to partially go in the water.

So remember how cold it is outside.

Think of how cold the water is.

And then when you get out of this,

now you're wind swept and you're partially wet.

[gentle music]

- [Narrator] Although with the real risk of hypothermia,

Ronneberg pushes his men on.

As even after the river,

they still have a frozen 600 foot cliff to climb,

which leads right to the railroad line.

- So it's one thing on top of another, on top of another,

to try to make your way to this plant.

This is how important this raid is, that men are willing

to go to this length to make sure

that Hitler doesn't get his atomic weapon.

[gentle music]

- [Narrator] Incredibly, Ronneberg and his men

make it all the way across the gorge

and reach the railway line.

- Extremely challenging, extremely demanding.

And let's not forget,

that besides all these physical demands,

there's also the psychological demand of,

I've not come here just for a cross country's ski trip.

I actually have to go up and blow up a heavy water plant,

guarded by Germans.

- [Narrator] At around midnight on February 28th, 1943

the Gunnerside team is ready

to enter the heavy water plant.

[gentle music]

- So the team decides to split basically half and half.

There's a covering squad, provide protection.

And then there's the actual team,

that's going to set the explosives,

the team that's going to set the explosives knows

from Tronstad where to go.

[gentle music]

- [Narrator] Thanks to his reconnaissance,

they know they can enter the plant

via an unguarded utility tunnel.

[gentle music]

They sneak through the narrow utility tunnel

with their explosives

and finally gain access to the building.

- Until the last minute they have to make adjustments

and they have to tweak their plan

and respond to the situation as it is developing.

And they are now within sight.

And all that remains is to blow up the cylinders.

- There's Germans around.

You're probably scared.

You're you're making this dash.

You know that you have to be quick

and any small change to the plan

could throw off the entire thing.

- They finally reached the basement

and there's 18 massive containers.

And as Tronstad worried,

their worst fears are realized, they're full.

- The commandos run into one person, one of the Norwegians

who's working inside the plant and they confront him,

guns drawn because they're doing their raid.

And the Norwegian actually asks what they're doing.

They tell them that they're there to blow up the facility

and blow up the heavy water cylinders.

And the Norwegian asks,

are you here to kill me and all of us too?

And they say, no, we're not here to kill you.

It was very important to Tronstad and others,

that innocent Norwegians aren't killed in this raid.

[gentle music]

- [Narrator] The Germans at the Vemork Plant

are almost exclusively guards.

While the people doing the actual work

of creating the heavy water are all Norwegian workers.

During Germany's occupation of Norway,

many Norwegians are forced to work in factories

to help the German war effort.

Norwegians are prohibited from flying the Norwegian flag,

singing their national Anthem and even reading literature

that the Germans deem inappropriate,

can get you sentenced to death.

- The living conditions during the Nazi reign,

it was deplorable, shortages of medicine, shortages of food.

People lost their jobs,

homes were confiscated.

Freedoms and rights were curtailed, and on a drop of a dime

anybody could be accused of disloyalty.

German soldiers parading through the capital

It was a horrific moment for the people of Norway.

- Imagine being in Norway, imagine being under occupation,

the indignity of it, the paucity of

any kind of entertainment, of decent food,

of proper employment, the compromises,

that are constantly being made.

And this is I think something very hard

for the anglophone world to get their head around.

In Britain we don't have the heel of the jackboot

arriving in our country.

[gentle music]

- [Narrator] In the basement of the heavy water plant.

Ronneberg begins to set up the explosives.

Everything has led up to these crucial final moments.

And time is of the essence.

[gentle music]

- The explosives have to work in full for everything

to go properly.

Every one of the cylinders housing this water

needs to be taken out.

So they are issued explosives that are kind of like,

what we would think of is more like a C-4 putty.

It's kind of a thing that can be placed in different areas

and twisted around molded to a location

and then ignited through having a primer placed into it,

which is clipped off.

And then you have a few minutes to get out of there.

- [Narrator] But halfway through setting up the explosives,

it looks like the game is up.

- The blast team is busy putting their explosives

on the canisters when all of a sudden,

a window shatters next to them.

Now imagine why had to go through their mind.

They thought they were caught,

but it was one of the teammates.

Imagine the chaotic scene in their minds,

of what was transpiring when they realized

that one of their teammates was the one

who broke the window.

And I'm sure that he didn't hear

the end of that for a while. [laughs]

[gentle music]

- [Narrator] After a heart racing moment

of thinking they had been caught.

Ronneberg continues to finish setting up the explosives.

Meanwhile Stromsheim is sent to open

the exterior basement door

for an easy escape while Kayser guards

the Norwegian workers.

Every second spent inside the plant

increases their chances of getting caught

and the mission being a total failure.

Once Ronneberg is finished setting up all the explosives,

he cuts the fuse down from two minutes to 30 seconds.

He checks the explosives one last time and lights defuse.

[gentle music]

- The shorter the mission,

the less likely you are to get caught.

- The fuses are lit and the men exit

as quickly as possible out of the plant.

- I have no idea how these commandos managed to do this,

to set the fuse for 30 seconds.

When you're in the basement

of a massive hydroelectric factory teaming with Nazi guards,

there's so much that could have gone wrong,

but they managed to get out of the hydroelectric plant.

[gentle music]

- As they run out of the plant about 20 meters

or so they hear this distant funk.

It's not a loud bang, It's not a big explosion.

It's a nice little thump.

And they think, well, that's it.

That must be the explosions that are going off.

They're far enough away,

so the Germans don't see them at the time.

And one German kind of looks around and they see this guard,

just looking around, wondering what's going on.

He appears to be thinking about what that may have been.

- [Narrator] The Gunnerside team makes the escape

from the Vemork facility and alarms

eventually begin to go off.

Within an hour, the facilities chief engineer

and German guards arrive in the basement

to find the damaged to heavy water cylinders.

- So it's a perfect getaway,

for something that sounds like it's out of a spy novel.

And it works to perfection in that way.

The charges are laid, cylinders are broken.

The heavy water plant is disturbed for a while,

and the men get away.

- [Narrator] Ronneberg and his team,

retrace their steps through the gorge

and quickly get as far away

from the Vemork facility as they can.

They know the Germans will be right behind them,

looking for whoever had done this.

[gentle music]

- It's a highly successful operation,

especially considering the odds

and considering that this was somewhat telegraphed,

meaning that because of the earlier failure,

the Germans knew that it was a target

and yet still weren't able to prevent these very brave men

from carrying out an operation of that nature.

- When you think about the whole story,

you think about the distances that had to be traversed,

and then the precision with which the plant was targeted.

- The mission's a success,

there's a massive amount of heavy water

that literally goes down the drain.

[gentle music]

Top German General Von Falkenhorst,

comes to inspect the damage.

He ends up saying, it's a quote, unquote,

most splendid coup.

- The response of it, oh, it's a splendid coup,

it shows that some level there is respect

between combatants in the middle of a war.

For as much as you might have respected what they did

from a tactical standpoint,

you obviously don't want to let them get away

with what they did.

So you do put on this major manhunt to try to find them,

because this is the sort of thing

that you can't just let go.

You have to respond in kind in some way.

- 3000 soldiers are brought in to hunt down

this handful of commandos in Norway.

And to make the story even more compelling,

the commandos managed to allude thousands of German soldiers

combing the forest and countryside looking for them.

- [Narrator] Although the Germans vastly out number

the Gunnerside team in both people and resources,

Ronneberg and his team managed

to elude the Germans and make their escape.

[gentle music]

- Several of the commandos

somehow managed in the middle of the winter

to ski a few hundred miles to Sweden.

And they outdistance the German soldiers.

- They divide into two teams

and one stays in the local vicinity

to try to draw the attention of German forces

and be basically hides in the forest and in the mountains.

And then the other team skis to Sweden.

- It's a pure victory, it's a wonderful local,

moral high point.

Norwegians fighting back on the inside

against their German occupiers.

And then of course they are on skis,

they separate, they spread out.

They are nine little needles in a haystack.

- [Narrator] Having successfully sabotaged

the Vemork Plant,

Ronneberg, Kayser, Stromsheim and Haukelid

make the escape to Sweden.

- Sweden is next to Norway,

it's a fellow Scandinavian Country.

It's neutral, and from Sweden the commandos can get out

without being detected.

Also importantly, even though Sweden's neutral,

it's assisting the allies in various ways,

and there's an active resistance movement in Sweden.

And they're helping to train the Norwegian resistance

and intelligence counter forces.

News of the mission reaches the allies

as well as Leif Tronstad back in London.

And of course it's welcome news.

- [Narrator] The message Tronstad receives reads,

operation carried out with a hundred percent success,

high concentration plant, completely destroyed,

shots not exchanged since the Germans

didn't realize anything.

Germans do not appear to know whence the party came

or whether they disappeared.

[gentle music]

- Operation Gunnerside is one of the most successful acts

of sabotage during World War II,

carried out by Norwegian Patriots

who had no formal military background,

the SOE exercises are the only training they completed.

- It was a clean victory.

And that is the message that is transmitted

back to Britain. Scot-free.

We blew up the place, we blew up the cylinders,

didn't even blow up the place.

They just blew up the cylinders and we made a getaway

and we've all left with our lives intact.

[gentle music]

- [Narrator] Operation Gunnerside was a major success

for the allies and a crushing defeat

for the Germans nuclear weapons program.

[gentle music] [bomb explodes]

Throughout the German occupation of Norway,

the Norwegian resistance proves to be a crucial asset

to the allied forces.

What starts as a small sabotage unit,

will eventually grow into a full on military force

by the end of the war.

Some of the other victories for the Norwegian resistance

includes the destruction of two major German warships

called the Bismarck and the Tirpitz.

[gentle music]

- The Norwegian resistance comes out of that,

uniquely kind of Norwegian sense of identity,

which means that they were not willing

to be just assimilated into the Germanic Reich.

- [Narrator] Although Operation Gunnerside

was a success, by May, 1943,

the heavy water production facilities

were rebuilt and operating once again.

Later that year in November,

140 American bombers flew over and bombed the plant.

Unfortunately 22 Norwegian civilians were killed.

The exact tragedy Tronstad had hoped to avoid,

but this bombing raid finally crushes Hitler's aspiration

to build an atomic bomb once and for all.

As the German dictator has major problems elsewhere

and troops are taken out of Norway.

[gentle music]

- Norway is no longer the priority

that it was early in the war.

So they have to shift people out of Norway,

which is a response to what is happening

elsewhere in the war.

- So nothing's going right

for the Germans in that capacity and a place like Norway

becomes increasingly indefensible.

- [Narrator] While the Germans retreat from Norway,

Leif Tronstad continues with his work

in the Norwegian resistance.

This time taking part in operation Sunshine,

an operation to protect essential installations

and particularly power stations from being destroyed

by retreating German forces.

Tragically Tronstad will be killed during this mission.

- Tronstad's end is therefore kind of poetic in a twisted,

very ironic and sad fashion, right?

Because he dies the death that I suppose

he and other resistance fighters ultimately planned for.

- This kind of immortalizes him,

as one of Norway's great heroes. A scientist,

a resistance fighter, a chemist, and a fallen hero

in the fight against the Nazis.

- Him being part of that resistance afterwards

and continuing just shows the commitment

to the cause and shows how devoted he was to Norway.

This is again, the price that some people paid for this.

I mean that would've been enough danger,

for a couple of lifetimes faced by people like Tronstad

but the determination to keep fighting the Nazis

and to ensure that they're finally out of Norway.

[gentle music]

- [Narrator] Gunnerside team leader,

Joachim Ronneberg continues

his work in the Norwegian resistance

and goes on to lead other sabotage operations

against the Germans.

It is not until 1945 when he was awarded

Norway's highest military decoration,

the war cross with sword that he realizes the significance

of what he and his Gunnerside teammates had achieved.

Operation Gunnerside, the brainchild of Leif Tronstad

was a truly amazing act of sabotage.

This unorthodox frontline battle was a pivotal moment

during World War II, putting a major dent

in Nazi Germany's atomic plans

and undoubtedly changing the course of the war.

[gentle music]

- The course of history would've been completely different,

in a terrifying set of way.

[gentle music]

- Gunnnerside is a story that shows the dedication

that people during the Second World War had to the cause.

[gentle music]