Sabotage on the Frozen Precipice: The Mission That Stopped Hitler's Atomic Bomb

You are now listening to World War 2 Stories. I'm your host Steve Matthews. Today, I'll take you into the heart of one of the most consequential covert operations of the entire war - a mission so audacious and against such impossible odds that it reads like fiction. Yet every word of this story is true.

February 1943. While battles rage across Europe and the Pacific, a small group of Norwegian commandos are about to embark on a mission that might determine whether Hitler acquires the most devastating weapon ever conceived: the atomic bomb.

Their target: the Vemork heavy water plant, nestled in a nearly impenetrable mountain fortress in Nazi-occupied Norway. Their odds of success: virtually none. Their margin for error: absolutely zero. This is Operation Gunnerside - the remarkable sabotage mission that may have changed the course of history itself.

Episode Transcript

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You are now listening to World War Two stories.
I'm your host, Steve Matthews. Today I'll take you into the
heart of one of the most consequential covert operations
of the entire war, a mission so audacious and against such
impossible odds that it reads like fiction, yet every word of
the story is true. February 1943 While battles rage

(00:24):
across Europe, in the Pacific a small group of Norwegian
commandos are about to embark ona mission that might determine
whether Hitler acquires the mostdevastating weapon ever
conceived, the atomic bomb. Their target?
The Vemork heavy water plant, nestled in a nearly impenetrable
mountain fortress in Nazi occupied Norway.

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Their odds of success? Virtually none.
Their margin for error? Absolutely 0 This is Operation
Gunner Side, the remarkable sabotage mission that may have
changed the course of history itself, the nuclear shadow.
To understand the critical importance of this mission, we
need to step back and look at the terrifying scientific race

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unfolding beneath the surface ofWorld War 2.
By 1942, both the Allies in NaziGermany were pursuing a weapon
of unimaginable destructive power, the atomic bomb.
German scientists under Werner Heisenberg had taken an early
lead in nuclear research. Unlike the American Manhattan

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Project, which would eventually use enriched uranium, German
scientists had chosen a different path.
They believed heavy water was their key to controlling nuclear
fission and unleashing the powerof the atom.
Heavy water, or deuterium oxide looks identical to regular
water, but contains A heavier hydrogen isotope.

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It occurs naturally in tiny amounts, but producing it in
quantity requires massive industrial facilities with
specialized electrolysis cells consuming enormous amounts of
electricity. And there was only one place in
Nazi controlled Europe capable of producing heavy water in
sufficient quantities, the NorseKhydro plant at Vemork, Norway.

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The plant itself was a marvel ofindustrial engineering.
Perched on the edge of a 600 foot Cliff in the treacherous
fast Ford Valley, it was accessible only by a single
narrow suspension bridge. The Germans had transformed it
into a fortress with minefields,floodlights and multiple layers
of guards. Anti aircraft guns scan the

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skies while Gestapo agents patrolled the surrounding
countryside, executing suspectedresistance members and civilians
who aided them. Inside this fortress, heavy
water production continued day and night, with the precious
fluid being stockpiled for transport to Germany's nuclear
research facilities. Allied intelligence had

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confirmed the worst. If this heavy water reached
German laboratories in sufficient quantity, Hitler
might acquire atomic weapons ahead of the Allies.
Winston Churchill understood thestakes perfectly.
In late 1942, he authorized the Special Operations Executive
Britain Sabotage and Resistance Organization to destroy the

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Vmorg facility at any cost. The challenge was how to strike
a target so remote, so heavily guarded, and so critically
important to the enemy. The failed first attempt,
Operation Freshman, the first Allied attempt to sabotage
Vmorg, became one of the war's most tragic disasters.

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In N19422, gliders towed by Halifax bombers carried 41
British Royal Engineers across the North Sea toward Norway.
Their mission was to land, meet with Norwegian resistance, and
attack the plant. But in the howling winter winds
and near 0 visibility disaster struck. 1 glider crashed into a

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mountain, killing everyone aboard instantly.
The second glider in one of the towing aircraft crash landed.
The survivors, cold and disoriented in the Norwegian
wilderness, were quickly trackeddown by German troops.
What followed was an atrocity that underscored the stakes of
the mission. The captured British commandos,

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though in uniform and entitled to POW protections under the
Geneva Convention, were torturedby the Gestapo and executed
under Hitler's infamous Commandoorder, which demanded the
immediate execution of all Allied special forces captured
behind German lines. The grim news of Operation
Freshman reached London, along with intelligence that security

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at Vemorc had been doubled. The Germans were now fully alert
to Allied interest in the facility, making any follow up
mission even more dangerous. But the heavy water production
continued and the nuclear threatgrew by the day.
A second attempt would be necessary, but it would require
a completely different approach.The hunters in the snow.

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Enter the Grouse team. 4 Norwegian commandos who had
trained in Britain with the Special Operations Executive
Jens Anton Paulson, Arndt Gelstrup, Canute Hoglund and
Claus Helberg, parachuted onto the frozen Hardinger Plateau in
October 1942, weeks before the freshman disaster.

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Their mission was initially to provide ground reconnaissance
for the incoming British engineers.
When freshman failed, these fourmen found themselves stranded in
the Norwegian wilderness, haunted by German patrols, with
no extraction plan, minimal supplies and winter setting in
with full fury. The Hardinger Plateau in winter

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is one of Europe's most unforgiving environments.
Temperatures plunge to -30°C. Snow drifts can bury a man in
minutes. Blizzards can last for days, and
the sun disappears for weeks at a time.
For four months, these men survived by their wits and their
deep knowledge of Arctic survival.

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They built snow caves for shelter.
They haunted reindeer with silenced weapons.
They melted snow for water and stayed constantly on the move to
avoid German patrols. The team, now renamed Swallow,
radioed vital intelligence back to London while awaiting a new
mission plan, if they could juststay alive long enough for it to

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arrive. Their survival against such
overwhelming odds was itself a remarkable achievement.
But their real contribution to the war was yet to come, because
these men would become the pathfinders for one of the most
audacious special operations missions ever conceived.
The Gunner Side Team in London. SOE planners had learned hard

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lessons from the freshman disaster.
The next attempt would use Norwegian commandos exclusively,
men who could blend in with the local population if necessary,
who knew the terrain intimately and who were experts, skiers and
wilderness survivors. They would insert by parachute,
operate completely independentlyand escape over land through

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hundreds of miles of enemy territory.
Six men were selected for this near suicide mission, each
chosen for specific skills. Joaquin Ronneberg, just 23 years
old, was appointed team leader. A natural leader with ice water,
calm under pressure, Ronneberg had escaped Norway in 1941 to

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join the resistance in Britain. He would make the critical
decisions once the team was in the field.
Canoed Hochlid, whose sister Lees would later become a famous
nuclear physicist herself, was the team's demolitions expert.
He had helped develop the special explosive charges they
would use on the heavy water cells designed to destroy the

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machinery while minimizing the risk of civilian casualties.
Frederick Kaiser, Casper Island,Hans Storehawk and Berger
Stromsheim rounded out the team,all experienced outdoorsman,
weapons experts, and dedicated resistors of the Nazi occupation
of their homeland. The team trained relentlessly

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for months in the Scottish Highlands, whose terrain
somewhat resembled the Norwegianmountains.
They practice night navigation, demolitions, close quarters
combat, and tactical movement. They study detailed models of
the Vemorg plant, memorizing every corridor, stairwell and
guard position. They rehearsed their attack plan

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hundreds of times until they could execute it blindfolded.
But no training could fully prepare them for the reality of
what they would face. On February 16th, 1943, the six
men of Gunner Side boarded an RAF Halifax bomber and took off
for Norway, knowing their chances of returning alive were
slim at best. The Drop The Gunner Side teen

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parachuted into Norway on a night of howling winds and
blinding snow. Whether so severe that the pilot
could barely keep the aircraft level for the drop, the team was
blown far from their intended landing zone, their equipment
containers scattered across miles of snowfield.
After a harrowing night huddled together for warmth, they spent

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days hunting for their supply containers, finally recovering
the critical explosives and equipment.
They then began an arduous week long trek across the Hardinger
Plateau to rendezvous with the Swallow team.
Navigating by compass through whiteout conditions, always
watchful for German patrols, themeeting between the two teams

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was a moment of quiet triumph inthe frozen wilderness.
The Swallow team, who had somehow survived months in these
brutal conditions, had current intelligence on German defenses
and had identified potential approach routes to the target.
Together the now 10 man force began planning their assault on
one of the most heavily guarded industrial facilities in

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occupied Europe. What they discovered was
sobering. Since the freshman disaster, the
Germans had further fortified the Vemorg plant.
Mines had been laid. Guard dogs patrolled the
perimeter. Searchlights swept the
approaches. Machine gun nests covered the
suspension bridge, the only apparent access route.

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A Garrison of troops was stationed in the plan itself,
with more forces nearby that could respond within minutes.
A frontal assault was suicide. They would need to find another
way in. In Ronneberg, studying the lay
of the land through binoculars identified a possible approach
that the Germans had deemed impossible.

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The gorge below the plant, a narrow gorge, dropped nearly 600
feet to the icy river below. The Cliff face was almost
vertical in places, covered withice and loose rock.
The Germans had not bothered to guard it.
No sane person would attempt to climb it, especially in the dead
of winter while carrying explosives and weapons.

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Ronneberg decided this impossible route was their only
chance. On the night of February 27th,
1943, after several days of careful reconnaissance, the
saboteurs made their move, leaving behind four men as a
covering force. 6 Commandos, Ronneberg, Hawklid, Kaiser

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Island Store, Hog and Stromsheimbegan their descend into the
gorge in darkness. Carrying 40 LB packs filled with
explosives, they picked their way down the treacherous slope.
One slip meant certain death. The temperature was well below
freezing, the rocks slick with ice, visibility limited to a few

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feet. Somehow they reached the bottom
without mishap and crossed the half Rosen River.
Then came the truly daunting task, scaling the Cliff on the
other side to reach the plant perched on the edge above them.
For hours they climbed in silence, using all their
mountaineering skills to ascend without the slodging rocks or

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making noise that would alert the guards patrolling just
meters above their heads. Near midnight, exhausted and
cold, they finally reached the perimeter fence.
Using wire cutters wrapped in tape to muffle any sound, they
created an opening and slipped through.
Now inside the outer security cordon of one of the most
heavily guarded facilities in the Third Reich, the sabotage,

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the commandos now face the most dangerous part of their mission.
Penetrating the plan itself, their intelligence indicated a
basement entrance on the side facing the gorge, one less
heavily guarded than the main doors.
Moving silently through the shadows, they reached the door
and found it locked. In a stroke of luck that seemed

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almost providential, they discovered a cable duck leading
into the basement. One by one, they squeezed
through the narrow opening, finally reaching the interior of
the plant. They were now in a race against
time. At any moment, a guard patrol
could discover them. Following their memorized plan
of the facility, they navigated through dimly lit corridors

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toward the heavy water production room.
At one point, they froze as a Norwegian civilian worker
appeared suddenly before them. After a tense moment, they
determined he was not a securitythreat and let him go.
Or risky decision, but one that avoided unnecessary bloodshed.
Finally, they reached the room containing the electrolysis

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cells used to produce heavy water.
Working with practice deficiency, they placed their
specially designed explosive charges while Ronneberg set the
timers for 30 seconds, barely enough time to clear the area,
but they couldn't risk giving the Germans time to discover and
disarm the explosives. As the fuses began ticking down,

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the commandos made their escape through the same route they had
entered. Just as they cleared the
building, a muffled explosion rocked the plant.
There was no massive fireball orcatastrophic structural damage.
Their charges had been preciselycalibrated to destroy only the
critical heavy water cells whileminimizing the overall
destruction inside. The explosion had shattered the

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electrolysis chambers and sent approximately 500 kilograms of
heavy water, enough for months of German nuclear research,
flowing down the drains. The mission was a success, but
the saboteurs were still deep inenemy territory, with every
German soldier in the region about to be on high alert.
The escape What followed was oneof the most remarkable escape

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and evasion operations in Special Forces history.
The commandos split into two groups to maximize their chances
of escape. Five men, led by Ronneberg,
headed for the Swedish border 250 miles away across some of
Europe's most forbidding terrain.
The others, including Hauklid, remained in Norway to continue

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resistance operations. The German response was swift
and furious. Within hours, hundreds of troops
were combing the mountains. Roadblocks were established on
every possible escape route. Aircraft conducted daily
searches of the plateau. The Gestapo began a campaign of

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reprisals against local Norwegians suspected of aiding
the resistance. Yet somehow Ronneberg's group
managed to stay ahead of their pursuers.
Skiing over 50 miles in near Blizzard conditions, they
reached a safe house where civilian resistance members
provided food and critical intelligence on German patrols.

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From there they continued their remarkable journey towards
Sweden, traveling only at night,hiding in barns and remote
cabins during daylight hours. After two weeks of constant
movement through deep snow and sub zero temperatures, always at
risk of discovery, the exhaustedcommandos finally crossed into
neutral Sweden. They had traveled more than 200

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miles on skis, carrying minimal supplies through some of the
harshest winter conditions imaginable, all while being
hunted by thousands of German troops from Sweden.
They were eventually transportedback to Britain, where the full
impact of their achievement was becoming apparent.
Against overwhelming odds, they had dealt A crippling blow to

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the Nazi nuclear program withoutfiring a single shot or losing a
single man. The aftermath The Germans,
desperate to recover their heavywater production, quickly
repaired the Vemorg facility. But the sabotage had destroyed
critical equipment that couldn'tbe easily replaced, and the
months long delay proved crucialto the Allied war effort.

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Even once production resumed, the Nazi nuclear program faced
continuous setbacks. Allied bombing raids targeted
the plant repeatedly, and in a final act of sabotage in
February 1944, Canoed Hakalid, who had remained in Norway,
orchestrated the sinking of the ferry Hydro as it attempted to
transport the remaining heavy water stocks to Germany.

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The ferry and its irreplaceable cargo now rest at the bottom of
Lake Tinsjo, 1300 feet below thesurface.
These combined actions ensured that German scientists never
acquired enough heavy water to build a functioning nuclear
reactor, A prerequisite step toward developing atomic
weapons. By the time the war ended in

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1945, the Nazi nuclear program had made frustratingly little
progress while the American Manhattan Project raced toward
completion. The strategic significance of
Operation Gunner Side cannot be overstated.
General Nicolaus von Falkenhorst, the German
commander in Norway, called it the most splendid coup he had

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witnessed in the war. Allied military leaders
recognized it as a textbook special operations mission, and
years later, nuclear historians would identify it as a critical
turning point in preventing Hitler from acquiring atomic
weapons. Had the sabotage failed in Nazi
Germany, developed nuclear bombseven a few months before the

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Allies, the outcome of World War2 might have been
catastrophically different. Cities like London, Moscow, and
perhaps New York might have suffered the fate that later
befell Hiroshima and Nagasaki. The course of human history
itself hinged on the courage andskill of those Norwegian
commandos. On that frozen February night,

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the human stories behind the strategic importance of Gunner
Side lie remarkable human stories of courage and
resilience. Joaquin Ronneberg, the 23 year
old mission leader, returned to Norway after the war and lived
to the remarkable age of 99, passing away in 2018 as his
country's most celebrated war hero.

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Throughout his long life he remained humble about his
achievement, insisting he had simply done his duty.
Canoed Hawkel had continued resistance operations in Norway
until liberation, surviving numerous close calls with German
patrols. His sister Lise Meitner, who had
fled Nazi persecution, ironically became one of the

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leading nuclear physicists of her generation, contributing to
the very field her brother had helped the night to Hitler.
The men of the Swallow team who survived months on the Hardinger
Plateau all had distinguished resistance careers.
Canute Hoglund later joined ThorHairedall on the famous Contiki
expedition, crossing the Pacificon a balsa raft, perhaps finding

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the open ocean less daunting than those frozen months evading
Nazi patrols. The most poignant story belongs
to the Norwegian civilian workers at VEMORC.
Though they knew that sabotage of the plant might result in
brutal reprisals against the local population, many secretly
supported the mission. Some provided critical

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intelligence to the resistance, Others deliberately performed
maintenance poorly to reduce production.
Their quiet heroism, for which they sought no recognition,
exemplified the Norwegian spiritof resistance.
Legacy and lessons Operation Gunner Side has studied today at
military academies worldwide. As the gold standard of special

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operations, it's lessons remain relevant in Modern Warfare.
First, the mission demonstrated that small teams of highly
motivated and specially trained operators can achieve strategic
effects far beyond their numbers. 10 men changed the
course of the nuclear arms race.Second, it highlighted the

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crucial importance of local knowledge and support.
The Norwegian commandos familiarity with Arctic survival
techniques and mountain warfare made them far more effective
than conventional troops would have been in the same
environment. 3rd, it showed the value of precision and strategic
sabotage. By targeting only the critical

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heavy water cells rather than destroying the entire plant, the
commandos minimized civilian casualties while achieving their
military objective. An early example of what we now
call surgical strikes. Perhaps most importantly,
Gunner's side stands as a testament to human courage and
ingenuity. Against seemingly insurmountable
odds, these men faced not just the formidable German military

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machine, but also some of the most extreme conditions nature
can produce and prevailed against both.
In Norway, the operation has become a defining national
legend. The Vemor plant is now a museum
where visitors can trace the Commandos route and see
recreations of the heavy water cells they destroyed.

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Norwegian schoolchildren learn the story as a proud chapter in
their history, and the few surviving artifacts like
Ronneberg's wire cutters and compass are treasured national
relics. But beyond Norway, this
operation deserves wider recognition as one of the most
consequential acts of courage inthe war against Hitler.

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Without firing a shot, without losing a man, a small team of
determined saboteurs struck a blow against Nazi Germany's most
terrifying ambition. And in doing so, they may have
saved millions of lives and preserved the world as we know
it. This has been World War Two
stories. I'm Steve Matthews.

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Join us next time as we continueexploring the moments that
shaped the greatest conflict in human history.