Ah your right, apologies. I was getting Operation Chastise (an attack by specialized bombers on the Ruhr valley hydroelectric dams and the subject of the movie

Ah your right, apologies. I was getting Operation Chastise (an attack by specialized bombers on the Ruhr valley hydroelectric dams and the subject of the movie) confused with Operation Freshman (an attack by commandos on a German controlled dam in Norway that produced heavy water).