UNDER cover of darkness, commandos mounted the most daring and successful sabotage raid of World War II, halting the Nazi regime’s development of an atom bomb.

Immortalised by movie The Heroes Of Telemark, the raid on the heavy water cellar at Vemork in Norway took place in the night between February 27 and 28, 1943.

The power plant and heavy water cellar (Photo: Zenisk AS)

Now, the scene of Operation Gunnerside is to be opened to the public as a tourism and education attraction after painstaking work by industrial archaeologists.

After years of excavation and planning, the original cellar will officially open on June 18 this year, with a new museum facility to tell the story of the raid at the place where it was staged.

The new museum at the site (Ill: Point AS)

The heavy water cellar at the Vemork hydroelectric power plant near Rjukan, is regarded as a historic heritage site of significant national and international importance.

Operation Gunnerside was an extraordinarily courageous act of sabotage. The Hydrogen Production Factory was fortified and heavily guarded in a nearly inaccessible part of Norway.

Some of the Gunnerside team (Photo: Leif Tronstad samlingen)

Penetrating the location in the frozen mountains of Telemark, Norwegian commandos under British command successfully destroyed the heavy water production that might have made it possible for the Nazis to develop an atomic bomb.

Raid leader Joachim Rønneberg and Fredrik Kayser entered the heavy water cellar where the high-concentration heavy water was being produced in eighteen production units.

One of the rooms as discovered (Photo: Tomasz Wacko/NIA)

They climbed into the cellar through a narrow tunnel used for cables, set their charges, and the resulting explosion completely destroyed the production units, with no human injuries.

The operation was carried out without a single shot being fired, and the saboteurs escaped, some of them skiing for all of 17 days to reach safety in Sweden.

The spectacular story is known worldwide, especially through movies like Operation Swallow: The Battle For Heavy Water (1948), The Heroes Of Telemark (1965) and The Heavy Water War (2015).

Joachim Rønneberg was just 23 years old at the time of the raid and has repeatedly stated that the cellar where the action was carried out should be made available to the public.

Joachim Rønneberg in uniform. (Photo: NIA)

Anna Hereid, Director of Norwegian Industrial Workers Museum (NIA) says: “In light of present day Europe, it is vital that we place great emphasis on telling the story about past times.

“As the scene of one of the most spectacular events in the history of Norway, the heavy water cellar is a major destination for education in history and a monument to the Second World War. 

Anna Hereid, at Tinnfoss, Notodden in Telemark. (Photo: NIA)

“Surrounded by a dramatic landscape, the cellar and the new museum will be a place for learning and reflection.”

The story of the rediscovery of the cellar is a gripping story in its own right. 

The Hydrogen Production Factory was demolished in 1977, and the cellar was effectively lost. But in September 2016 the NIA began excavations to try to locate the site.

Excavation work (Photo: Tomasz Wacko/NIA)

On October 5, 2017 there was a breakthrough as the heavy water cellar was found – intact and in good condition.

A special focus of the excavation was to gain more knowledge of the specific target of the Norwegian saboteurs. All that was found has been kept intact for better understanding, observation, and research by current and future generations.

For more on the remarkable Telemark story, and the new centre, take a look at the official website, and for a virtual 3D tour click here. Lead archive image on this post courtesy of the NIA.