Ferry Command was formed on 20 July 1941, by the raising of the RAF Atlantic Ferry Service to Command status. Its commander for its whole existence was Air Chief Marshal Sir Frederick Bowhill. He was also the first commander of Ferry Command's successor, Transport Command.
As its name suggests, the main function of Ferry Command was the ferrying of new aircraft from factory to operational unit. Ferry Command did this over only one area of the world, rather than the more general routes that Transport Command later developed. The Command's operational area was the north Atlantic, and its responsibility was to bring the larger aircraft that had the range to do the trip over the ocean from American and Canadian factories to the RAF home Commands.
This was pioneering work: before Ferry Command, only about a hundred aircraft had attempted a North Atlantic crossing in good weather, and only about half had made it. Over the course of the war, more than 9,000 aircraft were ferried across the ocean and, by the end of the war, crossing the Atlantic had become a routine operation, presaging the inauguration of scheduled commercial air transport services after the war.
Ferry Command was subsumed into the new Transport Command on 25 March 1943 by being reduced to Group status as No. 45 Group. No. 45 Group still retained responsibility for Atlantic aircraft ferrying operations, but Transport Command was a worldwide formation, rather than a single-mission command.