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September 20, 2017

The Norwegian Heavy Water Sabotage: Stopping Hitler’s Atomic Bomb

Norway became the first country with a commercial plant for producing heavy water when Norsk Hydro went into operation in 1934. In 1940, Norway was invaded by Nazi Germany, and control of the plant fell into German hands. It now controlled most of the world’s heavy water production, which was an essential process in the race for developing nuclear weapons. With the start of World War II, German control of this process was very concerning to the British, and later to the American Allies, since this meant that Germany might win the race to weaponizing nuclear power before the Allies. They decided to remove the heavy water supply and destroy the plant by aiming raids targeting the power station supplying power to the commercial plant.1 However, prior to the German invasion of Norway, French military intelligence decided it would be necessary to remove a fraction of the heavy water and transport it to France during the war.2

Germany started to procure heavy water in late January 1940. In response, British Special Operations Executive (SOE) started planning several operations aimed at limiting or completely stopping German production of heavy water. The first operation, code-named Operation Grouse, launched on October 18, 1942.3 During this operation, four Norwegians parachuted onto a plateau above and near the Hydro plant. Their mission required them to gather as much information as they could regarding the plant and the heavy water operations. All the information that the team gathered was sent to SOE to plan for the next phase, code-named Operation Freshman. In this operation, a group of combat engineers were sent by gliders to join the Grouse team. Together, both teams were to set and detonate demolitions in key parts of the Hydro plant, and escape to Sweden.4

On November 19, 1942, Team Freshman left England to carry out their mission. However, the night of the operation, the weather conditions in the designated drop zones were extremely harsh, causing the first glider to crash into a mountain killing the entire crew. The second glider also crash landed, killing most of the people in the glider.5 Even after the gliders crashed, some of the crew members survived, but eventually they were captured by German soldiers, tortured, and eventually killed.

Due to the failed mission, Germans became aware of the Allied interest in the heavy water plant. This caused the Germans to increase the defenses in the perimeter, including establishing a mine field, floodlights, and deploying more guards on the site. However, this did not impede SOE. Planners continued to search for ways to send in commandos to link up with Team Grouse, which by now was renamed Team Swallow. All four members of Team Swallow lay low for several months in the mountains on top of the Hydro plant keeping contact with SOE by radio.6

Surrounding their boss Leif Tronstad (front row left to right) Jens Anton Poulsson and Joachim Ronneberg, and (back row left to right) Hans Storhaug, Fredrik Kayser, Kasper Idland, Claus Helberg, and Birger Stromsheim | Courtesy of Pinterest

After a while, SOE was able to finalize the plans for the next phase, Operation Gunnerside. In this operation, six more commandos parachuted in Norway on February 16-17, 1943. After several days, Team Swallow joined Team Gunnerside, and they started planning their assault, deciding to attack on February 27, 1943.

Several months had gone by since Operation Freshman, and the German defenses were still up, but security had become somewhat slacker. Only the bridge across the Maan River was still fully guarded, limiting their ways to get through the guards. The commandos realized that the only option they had to get inside was to climb down the 656 ft. ravine, cross the freezing river, and climb back up the other side of the ravine.7 Using information obtained, the teams then followed a rail line into the plant area without being detected by guards.

Once inside, they met with a Norwegian caretaker who assisted them in getting where they needed to be.8 The teams moved quickly into where the heavy water chambers were and placed the explosives, attaching a long time-delay fuse to the explosives. The saboteurs also made sure to leave a British sub-machine gun hoping to lead the Germans into thinking the sabotage was the British’s doing. They then lit the fuse the same way they came into the plant, and once they were clear of the plant, the explosives detonated destroying the heavy water chambers as well as 120 gallons of heavy water stored in the Hydro plant.

Reconstruction of Operation Gunnerside planting explosives inside the plant’s chambers (1943) | Courtesy of Wikipedia Commons

After the explosion, the Germans launched an all-out search for the commandos, but were unable to find them. All the commandos were able to escape the site, some into Sweden, others to Oslo, Norway, and some staying in the general area. After the successful execution, Germany started rebuilding the destroyed parts of the Hydro plant and produced more heavy water in the following months. SOE considered launching another operation but saw it as too difficult. So in November 1943 the US Army Air Forces were given orders to conduct bombing raids on the plant. Finally, after the bombing raids, the plant received extensive damage causing the Germans to halt production.

  1. Funk & Wagnalls New World Encyclopedia, 2016, s.v. “World War II.”
  2. Funk & Wagnalls New World Encyclopedia, 2016, s.v. “World War II.”
  3. Neal Bascomb, The Winter Fortress (Boston: Houghton Mifflin Harcourt, 2016), 30-35.
  4. Neal Bascomb, The Winter Fortress (Boston: Houghton Mifflin Harcourt, 2016), 45.
  5. Neal Bascomb, The Winter Fortress (Boston: Houghton Mifflin Harcourt, 2016), 109-111.
  6. Janet Voke, “Hero of Telemark: Janet Voke meets Joachim Ronneberg, survivor of one of the most daring actions of the second World War: the sabotage of a German heavy water plant deep in occupied Norway,” History Today 60, no.10 (2010): 57-58.
  7. Neal Bascomb, The Winter Fortress (Boston: Houghton Mifflin Harcourt, 2016), 189-192.
  8. Janet Voke, “Hero of Telemark: Janet Voke meets Joachim Ronneberg, survivor of one of the most daring actions of the second World War: the sabotage of a German heavy water plant deep in occupied Norway,” History Today 60, no.10 (2010): 50-59.

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Norwegian Heavy Water Sabotage

Recent Comments

Josselyn Arrieta-Meraz

I am glad this was able to come to an end but to think of the Norwegian lives that were taken because of such a dangerous mission, although it still is Shocking to think that Hitler had potentially had a nuclear bomb, and that it was operated on this plant for heavy water production. Overall an interesting and unique topic and information.

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04/10/2017

8:01 am

Troy Leonard

I really enjoy reading articles like this. I had no prior knowledge about the water sabotage. it is actually very shocking that Hitler almost had a nuclear weapon and he is the last person that should ever have one in his hands. that could have been a really bad event that could have taken place and many people would have lost their life if he did.

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20/10/2017

8:01 am

Alexandria Martinez

There are many details of wars that many people are unaware of, this article highlights something that I had never heard of before. It is because of those soldiers that don’t give up that many people have their lives. To think of everything that soldiers do, never giving up the fight and trying to keep others safe, is very nice and sad because of the many people that lost their lives, soldiers and civilians.

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13/11/2017

8:01 am

Tara Sellers

This article was very interesting and well written. However, I do wish the author had told us what the hard water was actually used for in the development of nuclear weapons. That way we could have a better understanding of the importance. Other than that, I really enjoyed the article. The fact that the French soldiers left a British weapon was interesting since they are supposed to be on the same side.

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13/11/2017

8:01 am

Benjamin Voy

This was a great article that kept me intrigued the whole time. I had no idea how close Hitler was to getting his hands on a nuclear weapon, he is the last person who should ever have one. Well him and Donald Trump anyway. Its also amazing to hear about all the soldiers that kept fighting and just would not give up. This is real perseverance. We are now living because of them.

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16/11/2017

8:01 am

Michelle Falcon

I had never known this event even or rather this part of Norwegian history. However it’s amazing to see how far people are willing to go to help those in need, even if that means putting their own lives at risk. I believe this article gave great insight into what was going on during this time period. It showed the struggles and the intensity if this mission, how even one wrong move could be catastrophic. over all this was a great article.

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16/11/2017

8:01 am

Megan Barnett

This article was an interesting read with all the team code names and the members trying to carry out a secret mission. However, I did not understand why SOE wanted the Germans to believe that it was Britain who successfully attacked the plant. Other than that the rest of the information was clear and understandable. Great job on sharing an unknown story!

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19/11/2017

8:01 am

Ryann Cervantes

I really liked the soldiers bravery but reading it again, I liked the danger that is felt reading about their missions. Even after the failure of the first attempt, the mission was still carried out. Yes it would be more difficult, but that’s how important it was, they still had to try. And even after Germany continued to work with the plant they decided to cut the small tactics and just bomb the whole facility.

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19/11/2017

8:01 am

Karina Nanez

This was a very interesting article to read. We learn about World War II is school, but I was never taught about all these missions that were conducted as ways to sabotage the German Army so they would not gain the upper hand in the war. What these men did was incredibly brave and put their lives in grave danger. I had also never heard of “hard water” before reading this, great article!

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19/11/2017

8:01 am

Josemaria Soriano

I am a physics major, and for me is really interesting to read an article like this one. The atomic bomb is a perfect example of how science can be used for the evil. Knowledge, in the wrong hands, can be completely destructive. Nowadays, there are a lot of scientists doing research projects about new technologies, without knowing that there discoveries are going to be used in war and destruction. I did not knew about this heroic action performed by the Norwegians. It is sad for me that nowadays history does not give the recognition these men deserve for their amazing action. Excellent article!

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20/11/2017

8:01 am

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