Hell Below

In the early weeks of the second world war,

A german u-boat commander attempts a daring raid

Into a british naval base.

As he deftly navigates between blockships sunk to keep the enemy out,

Suddenly he spots a chain hidden in the water ahead,

It obstructs his path and could ensnare his submarine.

He maneuvers quickly to avoid it,

A risky move in shallow waters.

If his boat is pinned by the current and it turns,

There's a great danger that it would be beached.

In world war ii, a subsea weapon allows

Warriors to fight from beneath the waves.

With cunning, force and tenacity,

Their enemies strike back.

Revolutionary but still sometimes primitive,

It's a desperate bid to change the course of war.

Their stories are legend.

September 4th, 1939.

North atlantic ocean.

In the opening hours of world war ii,

Hitler has given his u-boat commanders the go ahead

To hunt enemy targets.

300 miles off the coast of France,

German u-boat u-47 sits on the surface,

Having intercepted a merchant freighter.

German commander kapitanleutnant gunther prien,

Abides by the submarine protocol.

The protocol, says he has to stop the merchant men,

Search the merchant men, make sure that,

It's part of the allied shipping.

And then he's allowed to sink it.

Otherwise he had to let it go.

The merchant ship claims to be from neutral greece.

Prien summons the freighter's crew to prove they do not

Serve the allied cause.

But any interaction with another ship here on the

Surface could be fatal to a u-boat.

Because they may not stick to the protocol as well.

They may attack the submarine by ramming,

Or they may even be armed and use their artillery to destroy

Or damage the submarine.

Upon arrival, the crew from the freighter

Presents their paperwork.

Prien must review it and determine if the ship or

Its cargo poses a threat to the german war effort.

The submariners remains on high alert.

Ready to dive if an emergency appeal from the freighter

Attracts british forces.

Prien finally decides that the ship is greek and neutral.

It only carries resin that is in fact on route to germany.

He releases the merchant freighter and its crew.

They are free to go.

Gunther prien, the 31-year-old commander of u-47,

Has followed protocol and must continue his search

For a clean kill.

But hours later,

Prien receives word from u-boat headquarters.

Hitler is furious.

Another german submarine commander,

Fritz-julius lemp, has mistakenly sunk

The british ship ss athenia,

Less than 12 hours after the declaration of war.

Bound for montreal, athenia carried americans,

Canadians, and refugees fleeing europe.

For the germans, the sinking of the athenia is

Quite embarrassing.

And it resembled very much the lusitania incident

Of the first world war.

Which brought the united states on brink of entering

The war against germany.

It is exactly the mistake hitler wanted to avoid,

When he demanded his u-boat captains follow the

Submarine protocol to attack mostly military targets from britain.

It's very uncomfortable for the germans that a

German u-boat sinks a passenger liner,

And so creates another incident that could be used

By the british for some propaganda purposes.

And so they openly deny being responsible for sinking the athenia.

Hitler orders his u-boat commanders to be even

More careful when attacking.

Prien must now find a way to sink vessels under tighter scrutiny.

The next day, the crew of u-47 spots a

Vessel zig-zagging in the early morning light.

Prien draws closer.

U-47's gun crew readies again for action.

Submarine!

Prien fires a warning shot to signal the ship,

Ss bosnia to stop.

All ahead full!

But instead, the freighter tries to bolt.

On this occasion, the captain, rather feisty,

Decides he wants to get away from the u-boat.

He doesn't quite know if he, if he has a speed advantage or not,

So he increases speed, signaling all the time, sss.

Which means that he is being attacked by a submarine.

For german submariners,

This scenario confirms the impracticality of the

Submarine protocol.

They must surface to confirm the identity of the ship,

But by doing so make themselves vulnerable to attack.

You might say the u-boats fight in the first

Weeks of the second world war with one hand tied on their back.

However, by calling for military support,

Bosnia is now an active combatant.

So as bosnia tries to escape, prien orders his gunners to

Fire directly into the vessel.

Fire!

The german shells land on target

And a fire breaks out.

The british crew scrambles to abandon ship,

And overturn a lifeboat in the process.

As per the submarine protocol, prien provides assistance

To the british sailors.

And signals a passing norwegian ship to take the

Merchant crew onboard.

Having assured their safety,

He readies to torpedo ss bosnia.

Prien allows most members of his crew to come

To the top and have a look.

It's the first time that they see a torpedo hit a real

Target and nobody really knows what will happen.

So unlike lemp sinking ss athenia.

Lemp has to hide what he has done.

Prien was conferring to the submarine protocol and

Therefore the reich could claim it as the first

Submarine kill of the second world war.

But on September 8,

Hours after prien sinks a third ship,

The commander in chief of u-boat operations,

Commodore karl donitz, recalls prien.

When he arrives in germany weeks later,

Donitz summons him to meet.

On the table in front of donitz is a map.

Every german naval officer knew the story of

Scapa flow from the first world war.

It's a place of shame for the german high seas fleet.

Donitz has an audacious plan to strike a

Blow against the british royal navy in its own port.

He offers gunther prien the job.

1939.

Commodore karl donitz, commander in chief of german u-boat operations,

Presents kapitanleutnant gunther prien

The opportunity of a lifetime.

A chance to strike the british fleet in the security of its own port,

Scapa flow.

Scapa flow is a wonderful anchorage.

It's very large.

It's been used for a long time, the vikings used it.

But it came to prominence in the first world war,

When it became the major base for the grand fleet.

Located in the scottish orkney islands,

Scapa flow provides access to and protection from both the

North sea and the atlantic ocean.

And it allows a fleet there to stop enemy ships

Coming out into the atlantic or to attempt to and also to

Engage in blockade of germany.

Already during world war I,

The british secured the three main entrances with submarine nets,

Sunken blockships and even mines.

Multiple german u-boat crews tried to break in.

The last attempt was in 1918,

When the captain of ub-116 believed he found a way through.

The german commander reasoned that the main channel into

Scapa was so busy with allied ships,

That it must be free of mines.

He submerged and headed straight for

The front entrance.

But the german commander was horribly mistaken.

As the submarine unknowingly passed over a detection system,

An induction loop detonated the entire minefield.

Blowing the submarine, and its crew,

To pieces.

Now, despite the obstacles, donitz believes a skilled

Submarine commander could penetrate the defenses.

They present aerial reconnaissance photos and

Point out a gap in the british stronghold.

Although most approaches into scapa flow appear protected,

The british have yet to fully secure one of the channels to

The main harbor.

With a combination of skill and luck,

A u-boat might sneak through, and into the lion's den.

After only a day of contemplation,

Gunther prien agrees to lead the secret mission,

Code named 'special operation p'.

But in order to plan effectively,

Prien brings his first watch officer and navigator into his confidence.

They pour over tidal charts and reconnaissance photos

To identify a suitably dark high tide.

They select Friday October 13 during the new moon when

The skies would be darkest.

The moon phase also means higher tides,

Which would allow u-47 to navigate the shallow channels

Into scapa flow.

They also realize that this new moon is a so-called super moon.

Which occurs a few times a year,

As the moon travels closest to earth.

This increases the upper range of high tide,

Just a little bit more.

But October 13 is less than a week away.

And prien must finalize their plan and equip his