All language subtitles for Secret.Nazi.Bases.S01E06.Mystery.of.the.Nazi.Nukes.1080p.AMZN.WEB-DL.DDP5.1.H.264-BurCyg_track3_[eng]

- [Macphee] 1939, under
the cover of a forest

in Poland the Nazis
constructed one

of the largest complexes
of World War II.

- This is straight out
of a Hollywood movie.

- [Macphee] Covering
10 square miles

the complex was
built into the hills

and trees of Bydgoszcz,

transforming it into

a highly classified
industrial compound.

- This site is enormous.

- Over a thousand structures.

- How they hid all that?

It's amazing, really.

- [Macphee] The
workers had no idea

what they were manufacturing
at Dag Bromberg

and the allies didn't discover
it until the end of the war.

- This factory was
one huge secret.

- The most evil things
of the war were built

in Dag Bromberg.

- [Macphee] What dark
mysteries lie inside?

- One mistake could blow this
whole operation to pieces.

- It sends shock waves
that will propagate

through anything they
come in contact with.

- [Macphee] And how
did the Nazis keep

it hidden for so long?

- They've made this
complex as secret

as it could possibly be.

Why is that?

[dramatic music]

- [Macphee] January, 1945,

as the Soviet Red Army
advanced through Poland

soldiers stumbled upon a
massive abandoned Nazi complex

hidden in the Bydgoszcz Forest.

- When the Front rolls
in the Russian soldiers

just find a series of
abandoned buildings.

- [Macphee] The Germans
had fled the facility

just five days earlier,

destroying everything they
couldn't take with them.

- It was Nazi policy when
they withdrew from any kind

of territory to carry out
scorched earth policy.

That meant destroying
every document,

every building,
literally throwing
everything into the fire.

- Unfortunately, the
iron curtain was pulled

across the Soviet Union
and the world did not learn

for decades what
had happened there.

Perhaps the best kept
secret of the Nazi regime

is this Dag Bromberg facility.

- [Macphee] 1939, after
the annexation of Austria

and Czechoslovakia Hitler
turns his attention on Poland.

- The first of September
Hitler invades Poland.

Third of September Britain
and France declare war

on Germany as a result of that.

- [Macphee] Two months
after the invasion of Poland

the Germans begin
construction on Dag Bromberg

in the forest near GdaDsk.

By 1942 it spans a
vast 10 square miles.

- I live in Poland
and I have to admit,

I'd never actually heard about
the Dag Bromberg Complex.

- The camouflage and secrecy
of this site was so good

that it was not
discovered by the allies

until the end of the war.

- I'm standing, in fact,

in front of a building
which is enormous

but you would never
see this from the air

if you were an allied
fighter pilot or bomber

or reconnaissance
plane coming over.

It would be as if it
really didn't exist.

And you get the sense of
this place being so enormous

and yet so much of this is
hidden under this undergrowth

which is pretty thick.

As I'm walking around the
complex the guide I'm with,

Lukasz, is starting to tell me

that they don't actually
know what's over here

or they haven't
yet been over here.

I started to get a
little bit disoriented

because you quickly
lose yourself

in the undergrowth
in these hills.

But they're not hills,

it's a tunnel leading from
one part of the complex

to another and you
didn't notice it.

The construction seems
relatively simple.

You've got this main
production facility here

and what are these?

These are tunnels that lead in?

- Yeah, these are tunnels
that are connecting

those buildings and
now we are going

to the next building
that is just there.

Can you see him?

- Honestly speaking, you
can barely see anything

through the tree.

- And this is the way that
they wanted to just hide

this whole place here.

- And you can look up,

the foliage here,

these tree branches,

you wouldn't be able to
see anything basically

if you were flying
over 10, 15,000 feet.

- [Lukasz] Yes.

- Plus I'm assuming
they've got camouflage nets

that are over here as well.

So with the trees,

the camouflage nets,

essentially this
place is invisible.

- The overall aesthetic
at Dag Bromberg

is very unlike what
we've come to know

as big Nazi structures with
a kind of brutalist form.

These all take more
of a haphazard,

almost woodland kind of form.

- The other structures are
out there, they're imposing.

They're an expression of power.

They are meant to be seen,

whereas this facility
is very different.

It is so critical
to their operations

that secrecy is the
number one priority here.

- [Macphee] Construction of
Dag Bromberg was continuous.

Anything this large would've
been visible from the skies,

yet the ally's reconnaissance
would never spot it. How?

Location was key to keeping Dag
Bromberg a long term secret.

- There were three sites that
were scouted as possibilities

but this site was chosen

because of its
proximity to a river.

It had railways nearby
but also it had a form

of natural camouflage from
the undulating landscape

and the dense forest canopy.

- This forest was
sparsely populated,

so dense, so thick that
the Nazis could build

and operate there without
the Allies discovering it.

- They used the forest
as natural camouflage.

They created structures
that were uneven,

that were not too tall,

that didn't stick
above the treeline.

They landscaped the roofs
and the sides of buildings.

They buried structures.

They back filled things.

They made it look like
a natural landscape.

- [Macphee] The
forest camouflage

would be effective
once completed.

But to build such a huge
and spread out complex

the Nazis had to employ
large scale logistics

in and around the forest.

How did they manage such
a massive undertaking

while remaining undetected?

- There's an interesting
engineering dilemma that occurs

when you consider the
construction of this site.

It's an enormous site and
that's gonna need quite a lot

of engineering
infrastructure to build.

That kind of thing is gonna be
extremely visible from above.

But at the same time
you need to keep all

of this secret so how
did they manage it?

- You're bringing
in concrete mixers.

You're bringing in
dozers, excavators.

Typically in a situation like
this we would pave a road.

We would clear cut the
forest to knock down anything

that's in the way and we
would build with that.

They didn't do that.

- The Germans undertook the
most inefficient method possible

of bringing any equipment
that they needed to this site.

They essentially utilized
existing footpaths,

widened them ever so slightly
and painted them khaki

and these other
camouflage type colors

to maintain the secrecy of
the site so that the allies

did not know that it was there.

[clock ticking]

- [Macphee] Even if the
allies had discovered

the Dag Bromberg site,

how would they have known
it was worth bombing?

- By having the Dag
Bromberg site spread

over such a large area
with so many buildings

if the allies did discover it
through their reconnaissance

it would be very hard to
determine which buildings

were a priority.

None of them were
more conspicuous than
any of the others.

Another advantage of
having this site spread out

over such a large area is,

at the time,

aerial bombing was
not an exact science.

- For the first few years of
the war most of the bombers

that the Allied
forces are using,

they're just guided
by site, effectively.

It's no surprise really
that the average hit rate

for bombing missions
was very, very low.

You had no idea where
those bombs were landing.

They were just as likely
to murder sheep and cattle

as they were the enemy.

- [Macphee] Over the
course of the war

the bombers improved
and the RAF built

a sophisticated air
intelligence operation,

but they didn't
find Dag Bromberg.

- The Allies are flying
non-stop reconnaissance

by the middle of
the war, '43, '44,

to figure out what
the Nazis are doing.

Despite the success elsewhere
the Allies are unsuccessful

in finding Dag Bromberg.

This one stays a secret.

- It's almost unbelievable that
the Allies didn't spot this.

They had planes travelling
over Germany the whole time.

- Yes, they've made
only one plane picture

in '44, that's all.

- It's phenomenal,
you think about it,

you've got Allied
planes scouring Germany,

literally photographing
every square mile,

every square kilometer
of the country.

They're probably flying over
this complex every single day

and they never see it.

- That's the mysteries
of this place

because it's one of
the biggest mystery

in the Second World War.

- And of course if they
had known what was here

they would've sent over several
hundred planes to bomb it.

- I think so but not a
single bomb was dropped here

in the Second World War.

- [Macphee] But not all of
the risks came from the skies.

- So this is the most dangerous
part in the whole complex.

- [Macphee] What mysterious
terrors were created

under the forest canopy?

- It's very volatile
and it's dangerous

to work with these
things and they tried

to build an environment in
which they can contain that.

- [Macphee] What nefarious plans

were the Germans engaged
in at Dag Bromberg?

World War II,

the Nazis built a 10
square mile complex hidden

in a forest in Poland.

Thanks to a thick forest canopy

and the extraordinary
efforts taken

to camouflage this site,

the allies couldn't spot it.

- They've made this
complex as secret

as it could possibly be.

Now, they didn't do
that for other places.

They did here.

Why is that?

- [Macphee] The
occupation of Poland

was an essential
component in Hitler's plan

for world domination.

- Hitler and some other
Nazi leaders had this idea

of living space.

They wanted a greater
German empire, a Reich,

and part of that was Poland.

It stems from the
end of World War I.

With the Treaty of Versailles

it gives the city
of GdaDsk to Poland.

Hitler had always seen
GdaDsk as a Germanic city

and some of the lands he
desperately wanted back

as part of this greater Reich.

- [Macphee] Confident
in the superiority

of the German army,

the Nazis invaded Poland.

- Poland's defense
essentially collapses

after four weeks
of brutal fighting.

The western parts of
Poland is incorporated

into the Third Reich.

The rest of Poland
actually wiped off the map.

- [Macphee] Germany was
successful in taking Poland

but to engage Britain
and France would require

a whole new level of warfare.

- Hitler realizes he needs

to greatly expand the
Wehrmacht, the military,

more men, more weapons,

bigger, better technology,

bigger, better weapon systems.

- When Hitler occupies Poland,

essentially, he's getting
everything for free.

Any production facilities,

any logistics center,

any natural resource,

you name it,

the Nazis are gonna use
it towards their warring.

- One problem for Hitler though

with all these newly
acquired resources

is that these are very well
established facilities.

And so the Allies will
know exactly where they are

and exactly what they are.

The Nazi command the side
that they're gonna need

somewhere they can
produce what they need

in ultimate secrecy.

- [Macphee] In search
of new solutions

the Nazis turn to a company

they have long
collaborated with,

Dynamit Nobel AG or DAG,

built the Nazis one of the
largest munitions factories

in their enterprise,

10 square miles.

- This site is enormous.

By the end of 1944 it contained
1,000 separate buildings.

It had 400 kilometers of roadway

and 40 kilometers of railway.

When you think of
something that big

it's quite amazing they managed

to keep this whole
thing a secret.

- [Macphee] Here, the
Nazis would produce TNT,

smokeless powder
and nitroglycerin,

enough to supply the
German army the munitions

it would need for
a multifront fight.

- If you're gonna be
providing the majority

of the munitions
from one facility

the scale of this operation
needs to be significant.

It needs to be a
well oiled machine.

It needs to be able to
produce consistently

with quality and on time,

on budget and under duress.

How do you keep that secret?

It's amazing, really.

- The Nazis built

80 plus of these types

of munitions factories
around their empire.

Almost all the major Nazi labs,

weapons facilities get
bombed and bombed hard,

are rebuilt and bombed again,

taking them offline
enough to delay the Nazis

from developing these
horrifying weapons.

One of the few that
remains a secret

is this Dag Bromberg facility.

- [Macphee] Protection
from aerial bombing

was just the beginning of the
incredible engineering plans

that went into construction
at Dag Bromberg.

- You need to bear
in mind the materials

that are being produced here.

This is explosive materials.

They are designed
to do one thing,

to explode and cause damage.

The last thing you want
is to have that happening

at a time that you
hadn't planned for,

i.e. in the
factories themselves.

Not only are you gonna
lose all your materials,

you're gonna lose your
labor force inside there.

But possibly more
scary is the fact

that one explosion could set
off a whole chain reaction

within the factory and
you'd lose the lot.

- [Macphee] Determined to
protect their endeavors

from the highly volatile nature

of the materials
manufactured at Dag Bromberg

the Germans designed
extraordinary systems
into the site.

- The engineers
thought about this.

They situated the
buildings in certain ways

to prevent that chain
reaction from happening.

- The Germans took the
design to the extreme

by not building real houses

because an explosion in
one could very quickly

be transferred to another.

They went to great lengths
to ensure that the entrances

to different rooms were
not directly across

from each other for
fear that any blasts

could potentially set
off a chain reaction

in another room.

- They wanted to
accommodate the reaction

and so the mindset of these
engineers and designers

was driven by that need.

And it's a really
different approach

to engineering than we
typically would deal with.

- [Macphee] The destructive
impact of an explosion

was dependent on many factors.

The properties of
various substances

required different safeguards.

In order to facilitate
these factors

multiple structure
designs were built.

- The Nazis were aware that
there could be accidents,

that there could be explosions
and in order to mitigate

that risk they designed
their structures

and built them in a way

to control a release
unexpectedly of energy.

- One of the explosive materials

that was being manufactured here

was something called
smokeless powder.

When smokeless powder
is ignited it turns

from its solid state into
a gas at such a rapid rate

it sends shock waves
that will propagate

through anything they
come in contact with.

The other thing that
makes it so dangerous

is that it doesn't need oxygen
from the surrounding air

to detonate because it
contains within itself

its own source of oxygen.

- You could actually
cause an explosion

by compressing it and putting
it in a confined space.

So they had to beal with that
in a very different manner.

Throughout the facility
there were structures

called light
embankment buildings,

and they were built
in a manner to control

a potential explosion.

They had built up
embankments around the sides

of the buildings.

The earth would absorb
energy and dissipate

that energy through the earth,

but the majority of the
explosion would go upwards.

That would keep the
explosion local to that

and hopefully not spread
any sort of explosion

into adjacent structures.

- [Macphee] Alternately,
production buildings

that held more equipment posed
a greater risk of explosion.

They were designed to be
bunker-style structures

that would direct the blast
outward rather than up.

- They built rooms
with a blast wall,

three sides being
brick and a fourth side

a glass wall with an
earthen wall behind,

so that in the event
of an explosion

the glass would shatter
and the shards of glass

would essentially be
held by the earthen wall

allowing the energy
generated within the room

to essentially escape
without actually destroying

the rest of the structure.

- This is the blast wall you
were talking about, yeah?

- Yes, this is the blast wall

and this is original from
the Second World War,

made from wood and glass.

- Hang on a second, what's this?

This is an original
piece of the window?

- [Lukasz] Yes.

This is the glass that
were in those windows.

- Wow, so this has
survived almost 80 years.

What's actually inside?

I can see some kind
of wire netting.

- [Lukasz] Yes, it's a wire net

because if we get
an explosion here

the glass will be
thrown somewhere

and like knives
will cut everything.

And with wire the glass
won't be such a huge danger.

- So you've got
reinforced glass.

You got the special wire netting
that's been placed inside.

They're very obviously
paying very careful attention

to detail to all the safety,

make sure this plant
is as safe as possible

so it can carry on
producing munitions.

- Yes.
- And of course

the glass meant that no noise

would be coming from
this production facility,

so again, anyone outside
there wouldn't really know

what was actually going on here.

- Yes, exactly.

There was a road just
behind this building

and workers walk on this road

and they didn't
see this building.

It's impossible to see
him because he's covered.

- They built this entire
complex with creative ways

to prevent a chain reaction.

They didn't do it so much
to direct the explosion

in a certain way or
minimize the loss of life.

They did it so they
could quickly rebuild

and get back online.

- While the workers may
be expendable to Hitler,

the production is not.

This is key to the war.

- [Macphee] Nevertheless,
escape tunnels were provided.

- [Lukasz] If something will
go wrong in this building

the worker will just
run through that tunnel,

went here, hold those supports
that you can see on the wall

so the blast won't
throw him somewhere

in the forest and
he will be survive.

- If an explosion
takes place this kind

of little shelters offers
you no protection whatsoever.

- It's impossible
because you need to see

that something will go wrong,

just run through that tunnel,

run here to this chamber

and the chamber will be
destroyed after the explosion.

- And we're talking about
explosions that happen like.

[Ney clicking his fingers]

- Yeah, in one second,

not even in one second.

So it's only for the psychology.

And if at the start of your
job someone will tell you,

if something will go
wrong you will die,

you don't wanna came
here to the next day.

- Yeah and of course
your death would be lost

in this huge secret complex.

- Yes, of course.

- [Macphee] Some of these
structures would produce

a product so dangerous
it could only

be contained
entirely underground.

- Even shaking this compound
could set off an explosion.

- [Macphee] This material was
the key to terrible munitions.

- The Nazis weren't producing
just one type of explosive,

they were producing every
type and variety imaginable.

- [Macphee] What secrets did
the Red Army discover here?

Early in World War II
the Nazis constructed

the secret Dag Bromberg base,

a massive munitions
factory under the cover

of a dense Polish forest.

Because it provided a
third of the munitions

for the Eastern Front,

the Nazis put extraordinary
effort into keeping it secret

from the Allies and safe
from its own lethal products.

- So the whole time you're
living under this threat

that a single spark would
literally set this place alight.

- [Macphee] But there was
one ingredient made here

that required
extraordinary precautions.

- This leads through to the
main production facility?

- [Lukasz] Yes, to the
main building here.

- [Macphee] With no facade
the nitroglycerin facility

could only be accessed
via the service

and emergency tunnels.

- This is the place where
they made nitroglycerin.

There was a machine
called nitrater

and to this machine they input
sulfuric and nitric acid,

also glycerin and
they mix those.

And we've got nitroglycerin,

really unstable, dangerous
explosive material.

- Nitroglycerin is one of
the most explosive substances

that Hitler would've
had access to.

Merely shaking it
would be sufficient

to create an explosion.

- And so in order
to keep it stable

one of the conditions is to
make sure that the temperature

around it is kept at 20
degrees Celsius or lower.

That's another
engineering challenge

that had to be incorporated
into this base.

- [Macphee] In addition to
temperature being a concern,

static electricity
was also an issue.

- In the buildings in which
nitroglycerin was produced

the floors were
made out of lead.

Lead is a conductive material.

It will prevent any
sparks from forming

that could potentially
ignite the nitroglycerin.

- You can just imagine
the meticulous care

that was taken day by day,

building by building
to make sure

there were no
unintended explosions.

- So here exactly we are staying

there was a blast wall
made from wood and glass.

Also, the ceiling is rounded,

as you can see and all
walls are painted in white,

because if some acid or
nitroglycerin will go out

from the machine you
can see it on the walls,

because the color of
the wall will changed.

- And how many
people are working

in this particular
part of the facility?

- Only three of them.

- Just three people

in this room?
- Yes, exactly.

- [Macphee] Accidents an
sabotage were always a concern.

Laborers would be subject
to strict precautions.

- There were regular
contraband inspections

on this site to make sure
that nobody was bringing in,

either intentionally or not,

anything like matches
or cigarettes or metal

that could cause a spark.

And whether it was
intentional or not,

whatever you had that could
possibly cause a danger

would immediately
be confiscated.

- [Macphee] In order
to achieve production

with maximum secrecy
and further reduce

the risk of explosion,

materials were transported
between structures

in either overhead pipes
or underground tunnels.

- Typically, if we have
a liquid we would pump it

using mechanical pumps
across great distances.

The danger of using
mechanical pumps

is the potential for
electrical shocks

to ignite the nitroglycerin.

In order to avoid this they
used a gravity fed system.

- This is one of these
tunnels that was used

for transporting chemicals?

- They used pipes
and gravity force.

But nitroglycerin in
the Second World War

can sometimes be
thinner or thicker.

So the speed of the
swimming nitroglycerin

can be different so they need

to have exactly
the wanted speed.

And this support that you can
see is inputted by two screws.

You take out the screws

and change the height
of its support,

changing the angle of
pipes and you've got

the wanted speed of
nitroglycerin that will swim

to the next building.

- So it's quite a
genius solution, really.

They're using gravity.

- Yes.
- It doesn't cost

very much but it can be
individually calibrated

for the production
that they've got.

What happens if
they get it wrong?

- Explosion.

Every single mistake
makes an explosion.

- Okay, so it's kind of a
little bit ghoulish, isn't it?

Was it this dark at
the time or did they

have electrical lights here?
- No, they've got

here the electricity,

you can see it.

Here's the supplies
where the lamp was.

And wires, plenty of wires here.

- But this be quite
constricted here

'cause you got this tunnel here,

you got the tunnel,

you got the pipe, lighting,

it's pretty tight.

- Yes, but workers couldn't
move through those tunnels.

It was forbidden.

That's why they transport
those ingredients

in tunnels so a
worker that is working

in a different building,

he won't see anything.

- [Ney] So you've got this
production that's so critical

but they're also
trying to think about

how they can make
sure that anybody here

doesn't actually really
know what they're doing.

- [Lukasz] If you don't
know what you are doing

you don't have ideas
to sabotage it.

And here we are in
the next building

where the nitroglycerin
was cleaned

with new water.

- Because the water
was dangerous,

it had chemicals from
the actual production.

- Yes.
- And they couldn't afford

to have them there.

Wait a second, Lukasz,

what does this word say?

- [Lukasz] It's bath.

- So the pipe is
coming down here

and it's going through this?

- [Lukasz] Yes.

- And this is
original lettering?

- [Lukasz] Yes, from
the Second World War,

made by Nazi Germans.

- So I see this isn't the
only stamp you got here,

you got one here.

And what's this here?

- Here was a switch that was
changing the nitroglycerin

that was incoming to
this building here

and you can change the switch
to put this nitroglycerin

that is with new,

clean water, to
the next building.

And you've got numbers
of the buildings

as you can see here.

- So and engineers would
be standing right here.

- Yes, exactly
- 80 years

ago controlling the flow

of one third of all
of the production

of German military
explosive materials?

- For the Eastern
Front, of course.

- From this very spot?

- Yes.

For the nitroglycerin that went

and killed people on the Front.

- I mean, it's a
production facility

and it is so important

to what the Germans
are doing in the war.

It kind of brings a
chill to your bones.

- It's a little,

I guess, goosebumps here.

- So where are we now, Lukasz?

- Here was the mixing
nitroglycerin with
new, clean water.

- We've actually got a larger
piece of the glass here.

So you can see
it's pretty thick.

You got the

lacing of the wire.
- And the wires, yeah.

- But of course we're
talking about explosive power

that was so strong
that this glass

would've been smashed to pieces.

- Yes, but with wire,

huge pieces not small ones.

- And of course it's through
this glass that these workers

would've been looking out
with the only access they had

to the outside world once
they were working here,

cut off really from
the rest of life.

I don't know why but
just the cut of the glass

or the light or
just the sheer fact

that it's still
here after so long,

it makes me feel kind
of uncomfortable.

It's almost like this glass is
a symbol of something bigger.

- [Macphee] By 1944,
it was estimated

that Dag Bromberg
produced 30% of the demand

for munitions on
the Eastern Front.

- This is a critical base
for Hitler and the Nazis.

It's pivotal to
success in the war.

- [Macphee] But despite the
extraordinary precautions

the Germans took there
was always a threat

to the secrecy of the complex.

- Poland has the biggest
underground resistance

of the entire Second World War.

They've got eyes everywhere.

- [Macphee] One event
jeopardized this
critical complex

and even threatened
the entire Nazi effort.

Dag Bromberg was a secret 10
square mile munitions factory

camouflaged by the Nazis
in a forest in Poland.

The Germans took
extraordinary precautions

to keep the complex
hidden from the allies

and safe from its
explosive products.

But despite that threats lurked

in the forest around the base.

- Just one sliver of
information about what was going

on there in that camp
from the local resistance,

just one act of sabotage
could've blown the cover

of the entire complex

and led to its downfall
and destruction.

- Standard procedure
for a facility like this

would be to pat down
and check everybody

on the way in,

check everybody on the way out,

limit the access of
anybody working there

and station guards at
every entrance, every exit.

- [Macphee] To keep
factory operations secret

construction of the base
minimized any contact

with the nearby population.

- This is a critical base
for Hitler and the Nazis.

It's pivotal to
success in the war.

They were gonna go to
great lengths to make sure

that this facility
wasn't discoverable.

They needed to make it
completely independent

from any surrounding
communities,

any outside influence.

And so they essentially
built a town,

a place to live and work all
under the cover of the forest.

- So that everything it needed
it had to provide on site.

So we're talking
about electricity,

its own sewage system,

its own water supply.

It had its own laboratories,

its own medical facilities.

This base was so
highly classified

that even the
workforce had no idea

what it was they were building.

- The Nazis were very
good at propaganda,

at deceit and they used it
non-stop throughout the war.

But one of the more
absurd examples

is this massive concrete
hardened facility and tunnels.

They announced that
it was to make food,

including chocolate
and fruitcakes.

At least come up
with a better lie.

This is laughably absurd.

- [Macphee] The Germans
were taking no chances

with the secrets and
safety of the base

and created separate
production lines and workforce.

The two halves of the
factory would be separated

by the railway used
for production,

reloading and importing
raw materials.

- The western half of the
complex was codenamed Coal.

It contained production
lines for nitroglycerin,

for smokeless powder
and for nitrocellulose.

It also had a testing
facility for each of those.

And in the eastern half
of the complex codenamed

[speaking in foreign
language] or heat in English,

they had production lines

for trinitrotoluene
and dinitrobenzene.

- To ensure further
secrecy at this site

the areas were color coded.

Therefore the person that
worked in the nitroglycerin area

would have had a completely
different color code

from someone who worked
with smokeless powder.

- Making this all
the more remarkable

how the Nazis kept
this a secret,

the Poles had an
act of resistance.

They do manage to set
off a small explosion.

- [Macphee] In 1944,
Operation Cream resulted

in an explosion in
the nitration building

that destroyed rare
factory equipment

and killed German engineers.

- You can see that the
whole tower is damaged.

This concrete is
like house of cards.

- It's quite
literally snapped off

by the force of the explosion.

And this is exactly as it was
when the bomb blast went off?

- Yes.

- [Macphee] The roof of the
building was so badly damaged

it had to be removed
and replaced.

But production was back up and
running in just three months.

- So the explosion was violent.

These chemicals are
hugely volatile.

It killed everybody

in there.
- Inside the building.

- And yet the Germans are
immediately repairing it

and immediately
getting that production

facility back.
- Yes.

- And three months is a
pretty short amount of time.

- Yes definitely, they
need this nitroglycerin.

It was one of the most
important things here.

- And so this is the concrete
you're talking about?

- Yes, this is the rooftop
that was exactly here

in this building just behind us.

So they just put this
whole concrete here,

rebuilt the building and start
again with the production.

- So you got this enormously
thick concrete slabs

that just been literally
exploded in the air

and torn up like paper.

And then you've got this
concrete rebar here,

also really solid
and that's just,

in the case of these
explosions here,

has been snapped in
half like a stick.

- It's really damaged
because of one,

only one explosion here.

- Again, it just goes
to show just how fragile

this production facility
was to explosions,

bombs from the air,

all the kind of mistakes
that led to this blast.

- [Macphee] The
explosion was so powerful

it even caused damaged to
underground tunnels nearby.

- [Lukasz] Here you can
see again the collapses

after the explosion.

- Wait a second,

so the blast from the
production facility over there

has actually caused this
tunnel here to crack?

- Yeah.
- Man, that's

actually surprisingly powerful,

'cause this is rendered
the two walls apart.

They've literally cracked.

- Yes, because here
we've got the angle,

so the blast went
inside the angle

and just separate those
parts of the tunnel.

- So I imagine the German
military commanders

and the engineers here
must've been quite worried

when the explosion went off,

because they're thinking.
- Yes.

- Have they really
done everything

to prevent a chain
reaction explosion?

- The Polish resistance
is impressive

and it's reasonably
well organized

and it's pretty substantive.

But how they were not able
to penetrate this facility,

how they were not able
to notify the Allies

of precise maps, coordinates,

so that it could be bombed
is a disturbing reality

of this facet of the war.

- [Macphee] As the tides
of the war began to turn

the factory grew in
size and importance.

- The Allied forces would
have given their right arm

to know what was
happening there?

- [Macphee] What mysteries
were concealed in Dag Bromberg?

- So the secrecy is not just
from building to building,

it's quite literally
from room to room.

[clock ticking]

- [Macphee] Dag Bromberg
was a secret Nazi factory

hidden in a forest
in occupied Poland.

- The Germans aren't
putting this kind of effort

into every single munitions
factory plant they've got.

In fact, this place is
really quite special.

- [Macphee] The factory was
critical to the war effort,

providing one third
of the total munitions

for the Eastern Front.

In 1942, Dag Bromberg begins

its mass production
of gunpowder.

- Okay, we're coming through
the trees and I can see

what looks to be the biggest
building we've seen so far.

- [Lukasz] Yes, this is the
building where the nitroglycerin

was mixed with nitrocellulose

and there you've got gunpowder.

- The building is
absolutely enormous here.

How many people worked here?

- One people on each floor
and the third part of it

on the right side that
you can see was closed.

- I mean, the structure
itself is very imposing.

It's a little ominous looking.

I don't know,

maybe it's because
it's been damaged

and destroyed but it's kind of,

I don't know,

I get the sense of
evil lurking here.

- [Macphee] The secrecy of
the factory was so strict

even the workers had no
idea what they were making.

- We found a few years ago
a woman that worked here

in this building exactly.

She didn't knew anything
about the third part

of this building that
she was working in

because it was forbidden to go

across those stairs
here to the second part

and what about the third
part that was closed?

- So the secrecy is not just
from building to building

or from complex to complex,

it's quite literally
from room to room?

- Yes, exactly.

- So I mean you
can definitely say

that the whole secrecy operation
that the Germans had here,

the Nazis put in place, worked,

because people who were
even in this complex

don't really know
what's going on here.

- Yes, exactly.

You knew only the
place and the knowledge

about the place where you
are working and that's all.

- [Macphee] In its first
year the factory produced

over a thousand
tons of gunpowder.

By 1944, Dag Bromberg
would produce 13,700 tons

of the material.

- [Ney] What on earth
are we looking at?

- Here there was something

like a huge bath
with nitrocellulose.

And here on the wall
you've got switches.

The letter A is for open.

The Z is for closed.

So you open those baths
and the nitrocellulose

is falling to the mixers.

- So the Nazis have taken
the secrecy so seriously

that even that person doesn't
know what they're doing

and you've got thousands
of people working here,

relatively small workforce,

but they don't know
what they're doing.

- Yes.

- The only people who
do know are the people

who are getting shot at and
explosive artillery rounds

coming flying at them
'cause they're the ones

who are at the receiving
end of this production line.

- Yes, that's right.

Here is the hole that we
saw from the higher level

for throwing the nitrocellulose.

Here

were huge mixers

that makes nitroglycerine
and nitrocellulose

and there was only one
person working here.

And in those pipes
that you can see here,

nitroglycerin came here with
water to those two mixers.

And because nitroglycerin
came here with water

the gunpowder was
really, really wet.

So it fall down
to the next level

where we have a huge
centrifuge machines.

On a huge speed the
water was thrown out

and the gunpowder went
to the next floor.

And again, this building
is a dangerous one

so the ceiling is going up.

This corner, as you can see,

is rounded and we've got
the blast wall from wood

and glass of course.

- You've got all of this
material coming flying through.

You've got lorries
and trucks coming out

taking the material out.

Is it round the clock, yeah?

- Yeah.

In the night time
they use curtains here

to just black out the factory
because it's really easy

to see in the middle of
forest plenty of light.

- So the war is going on 24/7,

so the Germans can't afford
to let production stop.

It has to keep on going.

- It's impossible to
stop the production

because the explosive
materials all the time need

to be mixed and it's
impossible to stop the mixers

because there's a huge
chance for explosion.

- Again, when you just
think about the magnitude

of what was produced here,

not just for one
month or one year,

but throughout the course
of the Second World War

to kill millions of people.

It's eerie being here.

- Yeah.

- When you talk
to the survivors,

people who worked here,

do they mention that?

- No, maybe they don't
wanna think about it.

You are making ammunition
to kill your own friends.

After the centrifuging
the gunpowder

was a little bit wet so
it was put it into bags

and transport it to
the next building.

This is the place where the
hooks were for the bags.

And here on the,

let's say roof,

of this tunnel the
bags were transported

to the next building
where they used rollers

to just take the last of
water from the gunpowder.

Then it was cut it
into smaller parts,

put into crates and
transport it by train

to the next zone of the factory.

- Just give me a sense
of the scale here,

how many bags are coming out
of this production facility

on a daily basis?

- [Lukasz] To be honest,

we don't have any
information about that

but millions of
ammunition were made here,

so it was plenty of bags.

- [Macphee] Despite this
massive output of explosives

and gunpowder the German
army was losing ground.

- As the tide of the
war turns the Germans

become ever more reliant
on the Wunderwaffe,

these wonder weapons
that Hitler believes

are gonna transform his
chances and actually lead him

to winning the war.

- [Macphee] The work
at Dag Bromberg shifted

to secret weapons the Nazis
needed to give them an edge.

- One can only imagine
what they were working on.

- [Macphee] What
secrets fell hidden

behind the iron curtain?

World War II.

The mysterious Dag
Bromberg Factory in Poland

was producing a huge portion
of the Nazi's munitions

all while avoiding
Allied discovery.

- The efficiency of this complex
is absolutely spectacular.

They're producing 600 kilograms
of nitroglycerin an hour.

20 million riffle
shells every day.

- [Macphee] Between
1940 and 1944

the Nazis dropped 650,000
tons of bombs on the world

but the Germans struggled to
match Soviet tank production.

Desperate to find an edge
the Germans developed

never before seen technology
or wonder weapons.

- At Dag Bromberg
the German scientists

were manufacturing
a bewildering array

of explosive materials
and weaponry.

One can only imagine
what they were working on

in terms of for future projects,

what kind of research
was going on?

And yet again,

this is possibly another secret

of the Nazi regime
that eludes us.

- [Macphee] In 1943, a
testing range for ammunition

and rocket weapons was
established at the factory.

This would be the
training ground

for secret new weaponry
built in the factory.

- One of the secret
projects that was developed

and tested at
Bromberg was the 250

and a 500 kilogram aerial
bombs that were fitted

to the Nebelwerfer.

- The Nebelwerfer is a multiple
rocket launching device,

the likes of which no
army had ever used before

and it was gonna
be a game changer

on both the Eastern
and the Western Front.

Now, I've spoken to
people who have been hit

by Nebelwerfer attacks and
it's a terrifying experience.

They were loaded with gasoline.

They would burn
everything around them.

- [Macphee] Among the
many secret developments

in the last years
one in particular,

an experimental weapon
codenamed Rheinbote

could've changed the war.

- The Rheinbote was a
V4 ballistics rocket

which unlike its sisters,

the V1 and V2,

had the added benefit of
being highly transportable.

- Now ultimately, the V4
is not a successful weapon.

It can only carry
a 40 kilo warhead,

which is just 6% of the
entire weapon compared to,

say, 90% of the V2 rocket,

but it can travel a at
6,800 kilometers an hour.

- [Macphee] It was the only
long range ballistic missile

to enter into World War II,

but the Rheinbote would never
be used for its intended role.

- It's accuracy was
found to be wanting

and there were troubles
with its fuse system

whereby it would bury
itself in the ground

before the payload detonated.

And with such a
small payload onboard

that never caused
any huge damage.

[clock ticking]

- [Macphee] Production
at Dag Bromberg

would carry on almost
to the last minute

when it became clear that the
Germans were facing defeat.

- On their departure the
Nazis destroyed any evidence

and documentation about what
had been developed there.

You can imagine that
this was an entity

the Allied forces would
have given their right arm

to know what was happening there

and get hold of that
technology for themselves.

- [Macphee] The Germans
evacuated only five days

before the Soviets reached
the city of Bydgoszcz.

- So the Red Army hordes
roll over the Polish border.

They've come to liberate Poland,

or have they?

Actually, it's the
next occupying force.

The Soviets replace

one totalitarian
dictatorship with another.

They're here to stay
and they're here

to take away anything they want.

- Remarkably, over one
thousand trucks and wagons

were used to transport
everything back to
the Soviet Union.

Over one thousand,

that's how many secrets,

that's how many materials
were inside Dag Bromberg.

Only after the collapse
of the Soviet Union

is the world given just a
glimpse behind the curtain

of what was happening there.

But by then the ghosts of Dag
Bromberg are long, long gone.

- It's amazing, really.

The distribution of this
product across this stretch

for years is an amazing
logistical feat.

And to have this all done
in secrecy is a testament

to the engineers and the people

behind the design
of these structures.

- It's amazing, we've been
walking for half a day

and we've still only
seen a tiny spec

of the Dag Bromberg Complex.

- Yes, 1% of 25
kilometers square area.

- The Nazis managed to
build a city in a forest.

This is straight out
of a Hollywood movie

or some fantasy
novel or something.

An entire city with tens
of thousands of workers.

Scientists building massive
amounts of armaments.

The most evil things of the war

were built in Dag Bromberg,

many of them.

And yet, it was a
secret not for a year,

not for two,

not for three,

but the duration of the war
when the world's attention

is turned toward
the Nazi empire.

This is absolutely one

of the most remarkable
accomplishments,

unfortunately, of
the Nazi regime.

- [Macphee] At Dag Bromberg
the Soviets took everything.

The equipment,
materials and technology

would be a major factor
in the development

of modern Russian aircraft
at the end of World War II.

- Now, we know of course
that the Americans

under Operation Paperclip were
getting the brightest brains

and the best technology
back to America

to begin eventually
the Space Race.

Is it possible that the
Soviets got their hands

on the V4 Rheinbote
technology at Dag Bromberg?

And if so,

what other Nazi secrets did
they get their hands on?

- [Macphee] Today, the ruins
of the Dag Bromberg Factory

stand as an eerie
reminder of the havoc

and destruction its products
unleashed on the world.

But some of the site's
past experiments

and secrets may
be buried forever.

[dramatic music]