Norwegian heavy water sabotage

The Norwegian heavy water sabotage (Bokmål: Tungtvannsaksjonen; Nynorsk: Tungtvassaksjonen) was a series of Allied-led efforts to halt Nazi German heavy water (deuterium) production via hydroelectric plants in German-occupied Norway during World War II, involving both Norwegian commandos and Allied bombing raids. During the war, the Allies sought to inhibit the German development of nuclear weapons with the removal of heavy water and the destruction of heavy-water production plants.

Source: Wikipedia — Norwegian heavy water sabotage (CC BY-SA 4.0)