"Waiting to speak on Beser’s recorder, Lewis was groping for words to write in his log. There were those on board the plane who would insist his initial reaction to the mushroom cloud was: “My God, look at that sonofabitch go!” But Lewis later decided to pen: “My God, what have we done?”"
January 1, 1970
https://en.wikiquote.org/wiki/Atomic_bombings_of_Hiroshima_and_Nagasaki