A field command was a Starfleet leadership position based out in the field, i.e. open space, as opposed to one that was stationary, such as a starbase. In 2267, James T. Kirk was upset to learn that Commodore Stocker had replaced him as commanding officer of the USS Enterprise following Kirk's hype-raccelerated aging, as Stocker had never held a field command before. Though Spock attempted to explain that Stocker was the ranking officer aboard the ship, Kirk protested that the commodore was a "chair-bound paper-pusher" and ordered Spock to relieve him. (TOS: "The Deadly Years" )