Heroes on skis

The story of Claus Helberg and the sabotage at Vemork


Photo: Håkon Mosvold Larsen / NTB scanpix
The Vemork heavy water factory at Rjukan in 2018.

Michael Kleiner
The Norwegian American

Many Americans know the story of the Norwegian band of saboteurs who blew up the Vemork heavy water plant in Rjukan in Telemark in February 1943, altering the course of World War II. The Germans needed heavy water to produce an atomic bomb. But with knowledge of the terrain and a knack for skiing, the resistance was successful, despite the thousands of Nazi soldiers stationed there.

The story was popularized by the 1965 Hollywood movie The Heroes of Telemark, starring Kirk Douglas. But my own knowledge is a bit more personal. On a drive from Oslo to Telemark in 1990, my Norwegian friend Torbjørn Moum told me the story of one of those heroes, Claus Helberg, a story he had learned from an interview with Helberg on Norwegian television. He would later send me Helberg’s account that he wrote for Den Norske Turistforeningen Årbok in 1947. I translated it for inclusion in my book.



Photo: Erik Veigård / NTB Scanpix
Telemark hero Claus Helberg on a 1993 ski trip.

Planning the mission

Professor Leif Tronstad was responsible for planning the attack on Vemork. Not only did he have expertise that contributed to many Allied efforts, but he had also been involved in the building of the hydro plant as a chemical consultant for Norsk Hydro in 1934. Ironically, it was now his responsibility to figure out how to destroy the plant.

Helberg, together with Jens-Anton Poulsson, Knut Haugland, and Arne Kjelstrup, met with Tronstad in London in August 1942. All of them, except Kjelstrup had grown up in Rjukan. Poulsson was designated leader of the mission. To prevent the plans from being leaked, he was the only one who was informed of the importance of the assignment; the others knew nothing about the reason behind it.

The attack was planned for the winter, so the heroes had to pack anoraks, skis, and boots: not so easy to find in London in August. It would then be two months before they could return home. But weather proved to be the worst enemy, and bad luck didn’t help either. The first time they tried to land in Norway, the airplane’s engine caught fire, and they barely made it back to England. The second time, they had to turn back because of fog.

Finally, on Oct. 18, they safely parachuted into the snow-covered Hardangervidda. Their leader, Poulsson, called them together, and they learned that they were to destroy the heavy water plant at Vemork. They would have four weeks to carry out the operation.

Two English gliders with 40 Royal Engineers were to join them, so they had to find a landing place for them not too far from Vemork, since the English were coming without skis. Skolandsmyrene along Møsvatn had been chosen. Unfortunately, they had parachuted in farther west than planned, at Fjarefit east of the Songa River. It was 62 miles to Skolandsmyrene. It took two days to pack up in heavy snow.

On Oct. 21, the heroes began their march toward Skolandsmyrene. For 14 days, they traveled on bad terrain in terrible snow conditions. The ice was particularly treacherous on the rivers, so the band twisted along the steep birch-covered mountainsides, each carrying 30 kilos on their back, which was only half of their provisions. The food would last four weeks, so strict rationing was necessary.

On Nov. 10, they stopped at Sandvasshytta, a cabin about 6.2 miles from Skolandsmyrene, to wait for the gliders’ arrival. They were unable to communicate with England because of a bad battery, but a contact, a guard at Møsvassdammen named Torstein Skinnarland, provided them with food, fixed the broken radio, and provided information about Vemork.


Surviving the winter

The bad weather continued with harsh winds. It wasn’t until Nov. 19 that it subsided. They received word from England that the gliders would arrive that night. At 11 p.m., they heard the hum of the planes, and they lit the reception lights. It was quite an achievement that the gliders found them at all. But the next day they learned that only one of the planes returned to England; the rest went down.

The heroes stayed briefly in the hytte at Sandvatnet, only 3.1 miles from the German camp at Møsvassdammen. But it was unsafe, so they headed northwest to a hunting cabin not marked on the map. They stayed there for three months.

The location of the Germans was a worry, so Helberg went to Møsstranda to get the latest information from Skinnarland. There he learned that Skinnarland had been arrested. There were German raids in the area, and every house in Rjukan and Vestfjorddalen was searched. Everyone was asked if they had seen any Englishmen.


Photo: NTB scanpix
Sgt. Claus Helberg with a radio transmitter at the Hardangervidda during the last winter of the war.

Skinnarland’s arrest made the heroes’ food situation dire. For two weeks, they survived on rolled oats, a little margarine, sugar, and moss, which they dug up from under the snow and cooked. The lack of nutrition made them susceptible to disease. At one point, everyone but Poulsson was bedridden. He was a reindeer hunter, and knowing that the herds would soon be coming, his dreams of reindeer meat kept him going.

And there was more hope. In radio contact with England, they learned that six more men who had they had trained with would soon be joining them. This would make10 men against the 200 to 300 German guards at Rjukan and Vemork.

Then just before Christmas, reindeer started to come west from the plateau, and on Christmas Eve, Poulssen managed to shoot one.  For two months, the heroes lived only on reindeer steak, and ate the contents of the animal’s stomach to avoid scurvy.

It was a fierce winter, and sometimes they could barely step outside, let alone hunt. In addition to fighting frostbite and hypothermia, Helberg remembered how they had to keep peace among themselves. They created a study circle, and each night a different person delivered a lecture on any topic to divert their attention away from the problems they faced.

It wasn’t until the end of February that the weather cleared enough for the six other men to be dropped onto the plateau. Eventually, a new party, including leader Joachim Rønneberg, Knut Haukelid, Kasper Idland, Fredrik Kayser, Hans Storhaug, and Birger Strøms­heim, met up with Helberg and the others.

They discussed the best ways to penetrate the factory and return alive. One of the new men was inexperienced on skis. When the group informed him that he would have difficulty getting to Sweden after the action, he said he had not counted on returning alive. Helberg recalled, “This wasn’t particularly encouraging.”

To reach the factory, there were two alternatives. One was by a bridge over the steep gorge, but our heroes knew this was well guarded. If they tried to blow up the bridge, it would create noise, which could result in losses to their small group. The other was to ski down through the gorge under the bridge and come up unseen to the building. The contact at Vemork said it couldn’t be done, but our heroes also knew that the Germans would be taken by surprise.

The day before the attack, Helberg went into the valley to investigate possible ways to cross the river gorge. From the highway past Våer, just east of Vemork, he went down toward a cliff. After some climbing, he reached the river ice and found a serviceable road around the side of the factory. It would be a difficult road to take in the dark, but better than engaging the guards on the bridge. Helberg returned to the group, and at nightfall they set out for Vemork on their skis to scout out the route.

The plan was as follows: A lookout party would alert the others if the Germans sounded the alarm. If all was quiet, they would man their posts until the explosion was heard. If the alarm went off during their approach, the lookout party would attack the guards. When the explosion was heard, they would wait for the demolition party outside of the factory area. Orders would then be given for withdrawal with the password, “Piccadilly? Leicester Square!”

The demolition party was to destroy the heavy water building in the cellar of the hydrogen factory, accessing it by crawling through cable tunnels. The plans for the retreat were more difficult. It was impossible to try the steep mountainside on the south side of the valley. Going back the way they came meant a road guarded by the Germans.

Thus, the only way was to take the closed-down Kraftledningsvei (Power Line Road), which led to Krosso, parallel to the main road, about 31 miles above. From Krosso, they could follow the zigzag below the cable track up to the plateau. A minority of the heroes, including the leaders, preferred a retreat on the bridge at Vemork, perhaps less dangerous than Kraftledningsveien. However, most of the party felt if the attack on the bridge guards failed, they would all be prisoners. The majority prevailed.


The attack

On the night they began the march, it was cloudy with strong gusty winds. They were on skis with packs, dressed in British uniforms. Helberg remembered the ice on the road was as slippery as a skating rink. Climbing the cliff went better than expected. The water in the river overflowed but they were able to get across. Helberg and the lookout party leaned against the factory wall to avoid being spotted.

The demolition party found the doors locked, and the cable tunnel was not easy to find in the dark. They were separated, but the two men who had the explosives found the opening, just wide enough to crawl through. They decided not to waste time waiting for the others. They came to a room by the side of the heavy water building. The door was open. They walked in and found a worker there, who was frightened by the sight of them.

The two men began to lay the charges, as they had practiced in London. To prevent the charges from being removed, the men cut the fuse as short as possible. The leader lit the fuse. The worker went up the steps to the upper floors, while the demolition crew jumped out the cellar doors. Thirty seconds later, the room blew up.

Only the instruments were destroyed, so the building was still standing. This resulted in a slow reaction from the Germans. One guard stuck his head out the door of the guardroom, shined the light, saw the building was still standing, and lay back down.


The escape

This gave our heroes a head start, and it wasn’t until they were on the highway on the north side of the valley that the first cable cars with Germans started pursuing them. The heroes headed toward the city on skis. They discussed whether they should go toward the wooded mountainside. Those of the group who were familiar with the area said it would be too steep and they would run into the Germans. The cable cars were coming uphill toward Vemork on the road below the saboteurs. None of the group had considered going down toward Rjukan in the opposite direction as the Germans. At 5 a.m., the saboteurs reached the top of the valley and looked toward Vemork, satisfied with the commotion they had created.

They then separated. Five men, including the weak skier—Idland, Kayser, Rønneberg, Storhaug, and Strømsheim—skied to Sweden. Poulsson went alone to Oslo, eventually continuing on to Sweden and England. Haukelid and Kjelstrup went west and established headquarters for the resistance forces in the Vinje region. Kjelstrup returned to England at Christmas, while Haukelid remained in Norway until the end of the war. Haugland and Skinnarland operated a radio station in Hamrefjellene by Møsvatnet.

But Helberg had some exciting adventures following the sabotage. He returned to the mountains to retrieve the weapons and explosives that had been left there. To get food, he made his way to the hytte where the band of heroes had lived. When he found a pigsty there, he understood that Germans might be nearby. As he ran out, four or five men on skis came toward the cabin. Helberg quickly got on his skis. His only weapon was a Colt .32, so he would have to rely on his skiing ability to escape.

He was a good skier, but one of the Germans was better. After a while, the Germans began shooting at him. At a great speed, Helberg headed west, so the evening sun would be in the Germans’ faces while they were shooting. Fortunately, only one German could maintain the pace. The German got close, but he also had only a pistol, evening the chances: the best shooter would win. The German was so frightened when Helberg began shooting at him that he emptied his entire magazine—and missed. He threw his weapon down and headed back toward the other Germans. Helberg raced after him. Each second was valuable: the enemy soldier’s comrades could emerge from over the hill at any time. At 33 yards, Helberg took a shot at the German soldier, and thought he hit him.

The Norwegian hero turned around. The sun was going down. The ski tracks were a problem, because even in the dark, the Germans would be able to follow them. He set out for Vråsjøen. It was starry and quiet, but dark, and he fell over a cliff just north of Vråsjøen, breaking his left arm.

There was aircraft traffic, so he had to continue. He had yet to meet any Germans, even though they swarmed the area. With a broken arm, he couldn’t go back to the mountains; he had to get to a doctor.

Tired and hungry, he came to Hamaren, where he knew people. But the Germans were inspecting every farm at Møsvatn. After eating and resting, Helberg continued toward Rauland, broken arm and all. He had been on his feet for 36 hours and covered 16 Norwegian miles, over 99 American miles.

Helberg could not have chosen a worse time to arrive at Rauland. Josef Terboven and Wilhelm Rediess, the German commanders in Norway, had just been there to inspect the troops, which numbered 300 men. And with snow and sleet, it was impossible to continue.

Helberg knew a village shopkeeper at Austhø and was taken in there. He had to sleep on the kitchen floor, because the Germans had all the other rooms. He invented a story and tricked the Germans into believing that he was a local familiar with the area who had always wanted to help the Germans. A German doctor in Rauland examined him, and he was sent by ambulance to Dalen, where he could travel to Oslo on his own. In Dalen, he said “Auf Wiedersehen” to his helpers.

Helberg was to depart the next morning but needed to rest. He stayed at the tourist hotel, but Terboven and Rediess and their staff came to the hotel and took most of the rooms. Helberg was forced to remain. All the doors were locked, so he couldn’t run. All the guests were interrogated. Helberg’s identity card, made in London, was closely examined and found to be in order.

But the next morning, 18 guests, including Helberg, were arrested for “impudent behavior” against the Reichskommissar. Uncertain, Helberg decided to go along with the prisoner transport and look for an opportunity to escape. He put his pistol under the waistband of his ski blouse, but it fell out when a German soldier kicked him as he boarded the bus. Luckily, it was not discovered.

They drove two hours, and it was getting dark. Helberg saw his chance, opened the door, and jumped out. He went over the edge of the road and came to his feet just before the Germans on the motorcycles began pursuit. Exploding hand grenades followed the Norwegian into the forest. He was thankful to be in the dark, away from his pursuers, who, with time, gave up. After treatment at Lierasylet and a three-week stay at Drammen Hospital, Helberg traveled to England by way of Sweden.


Photo: Bjørn Berg / NTB arkiv / Scanpix
Some of the heavy water saboteurs from Linge Company reunited at one of the old sites where they carried out one of the war’s most famous sabotages. Back from left to right: Knut Lier-Hansen, Arne Kjelstrup, Rolf Sørlie and Hans Storhaug. Front, left to right: Joachim Rønneberg, Fredrik Kayser, Birger Strømsheim and Claus Helberg.

The end of the war

The Germans restarted Vemork following the explosion, but Allied planes bombed the plant. The Germans decided to try to transport the heavy water to Germany, but Haukelid blew up the ferry. Helberg was among nine men who parachuted into Ugleflott on Oct. 5, 1944. Among the other men were Poulsson, Kjelstrup, and Tronstad. They were to train resistance forces in Øvre Telemark. Helberg trained an elite troop of youth in weapons and field maneuvers in the mountains of the TinnRjukan district.

The war ended before the men and young boys had to engage in combat. Tronstad, however, never saw the Norwegian and Allied victory; he was betrayed by a traitor and killed.  Helberg wrote that Tronstad’s death was a great loss for Norway, not just for his knowledge, but because he had become so popular among the people in the rural areas through his humor and optimism. He earned their respect and there was great sorrow. The efforts of Claus Helberg, the Telemark hero on skis, and his companions in this isolated region helped significantly to change the outcome of the war.

This article originally appeared in the February 7, 2020, issue of The Norwegian American.

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Michael Kleiner

Michael Kleiner, business and sports editor, has more than three decades of experience as an award-winning journalist and public relations professional. He has operated his own PR and web design business for small businesses, authors and community organizations in Philadelphia since 1999. Not of Norwegian descent, he lived in Norway for a year with his family at age 11 and has returned as an adult. He is the author of a memoir, Beyond the Cold: An American’s Warm Portrait of Norway, and a member of NorCham Philadelphia. Visit Kleinerprweb.com; beyondthecold.com.