Joachim Rønneberg - Hero of World War II heavy-water raid

Joachim Holmboe Rønneberg, the leader and last surviving member of a 1943 mission that destroyed the heavy-water production facility in Vemork, Norway, died October 21 at age 99.

At age 20, Rønneberg was serving in the Norwegian army when, in April 1940, the country was overrun and occupied by Nazi Germany. With a group of friends, he commandeered a fishing boat and escaped to Scotland. There he joined Group Linge, the “Norwegian Section” of Britain’s Special Operations Executive (SOE), which ran sabotage missions in occupied Europe.

In November, 1942 Lt. Rønneberg was named to command a raid to disable the Vemork plant, which delivered heavy water used to moderate a crude nuclear reactor that was part of Germany’s attempt to develop the atomic bomb. He recruited five expert skiers from Group Linge, and on February 17 Operation Gunnerside parachuted onto the mountainous Hardanger Plateau. There, after weathering a five-day blizzard, they joined an advance party of four men who had survived since October by hunting reindeer.

During the night of February 27 the six-man team climbed down into the steep gorge to the hydroelectric plant that housed the heavy-water facility. Sneaking past the German guards, they planted their explosives and escaped, climbing out of the gorge on skis while guards searched for them at the plant. Not a shot was fired. Most of the group then skied a roundabout route, covering about 200 miles, to neutral Sweden, and returned to Britain.

The story has been told in numerous books and movies, most recently The Winter Fortress (2017) by Neal Bascomb and Kampen om tungtvannet (The Heavy Water War, 2015) by Norwegian Broadcasting (NRK).

Before the war’s end Rønneberg commanded two more successful sabotage raids into Norway. After the war, Rønneberg married Liv Foldal, and worked as a radio reporter and news editor for NRK, retiring in 1987. He lived in his hometown Ålesund, where a statue commemorating his wartime service stands in the town square. –Seth Masia