Werner Heisenberg's Copenhagen visit in September 1941 was one of the most consequential diplomatic failures of the war. But the real sabotage of the German atomic bomb project was more mundane and more heroic: in 1942, a Norwegian resistance fighter named Joachim Rønneberg — with a background in chemistry — walked into the Vemork heavy water plant, disabled the cooling system of the hydrogen sulfide reactor with a wrench, and set the production cells to produce sub-optimal concentrations of heavy water. He then ate his sabotage tools. The operation, known as Gunnerside, is considered one of the most successful acts of sabotage in history. What made Rønneberg extraordinary: he was a trained radio operator, explosives expert, and cross-country skier — all required for the mission. He was also a twin. He died in 2018 at age 99, the last surviving member of the operation. His final interview, given at age 97, lasted nine hours.