“NORWAY: Operation Freshman, a British-Norwegian assault on the heavy water plant at Vermork, fails completely after the sabotage team’s glider crashes. They were transported in two Horsa gliders towed by Halifax MK IIIs.”
http://en.wikipedia.org/wiki/Norwegian_heavy_water_sabotage
The Norwegian heavy water sabotage was a series of actions undertaken by Norwegian saboteurs during World War II to prevent the German nuclear energy project from acquiring heavy water (deuterium oxide), which could be used to produce nuclear weapons. In 1934, at Vemork, Norsk Hydro built the first commercial plant capable of producing heavy water as a byproduct of fertilizer production. It had a capacity of 12 t (13 short tons) per year. During World War II, the Allies decided to remove the heavy water supply and destroy the heavy water plant in order to inhibit the Nazi development of nuclear weapons. Raids were aimed at the 60-MW Vemork power station at the Rjukan waterfall in Telemark, Norway.
The Vermork heavy water plant was infiltrated by saboteurs in 1943 but was little damaged and back in production shortly thereafter.
Instead of attacking the plant again, the allies waited until the heavy water was being shipped to Germany via a rail car ferry crossing a large lake and scuttled the boat with explosives at the deepest part of the lake.