Captain Frederick Bock had flown many combat missions out of India and China before he was selected to be a part of the the 509th Composite Group in 1944.
He was given command of a B-29, which he named Bockscar. Before the Nagasaki mission, a mechanical complication forced Major Sweeney and the crew of the Great Artiste to comandeer the Bockscar to carry Fat Man. During the Nagasaki mission, he flew as the Commander of the Great Artiste, which acted as an observation ship, along with the rest of the Bockscar’s original crew.