I'm surprised anyone would think that Enterprise was probably Kirk's first command, or that anyone would prefer to think that. I think the main driver there is probably this thing Utopianvista writes: That's it. Fans have affection for a certain configuration of things, and don't want to see anything different. Kirk belongs in command of the Enterprise! And nowhere else. One thing that I always loved about the TOS world, and by contrast hated about the recent movie (Star Trek 90210), is the emphasis on professionalism. Spock and McCoy and Sulu and Uhura and Scotty, and Kirk, have long running careers as officers, that have put them into their current positions. They have resumes. They have experience. This is well exemplified by the record of citations read-out in Court Martial. It's definitely not like the movie where wonderboy Chris Pine can be captain on his first day, just because he might have some latent talent in that direction. You have to convert latent talent to proven ability, by discharging progressively greater responsibilities. Just the way the universe has always worked. To me, that notion of "careerism" or "professionalism" really made the world of Star Trek come alive for me, feel like a real place, an attainable place. A future I'd like to live in. It was an important part of making the seting believable. A show like Star Trek, which is asking for more suspension of disbelief that most shows do, constantly pushing science fiction concepts at its audience, has to be more scrupulous than other shows in making sure its common, familiar elements make intuitive sense. You have to drive some stakes in the ground for your audience, to help them accept radical change in other directions. One example would be how a career progression works. (And remember that World War 2 was in living memory for Star Trek's audience. As far in the past to them as George H. W. Bush's presidency is to us now. Naval officers were a visible segment of society.) (Also remember that Roddenberry described Kirk as a Horatio Hornblower of the stars. Hornblower commanded different vessels during his career; a different one in each novel, I think.) To me, the notion that Kirk was a brand-new commander when he took over the Enterprise, even if it's not in explicit disagreement with any piece of dialogue or anything we see onscreen, it sort of contradicts the whole spirit of early season 1, the whole feel, the whole milieu. Of course Kirk commanded some smaller vessel, maybe a "destroyer class" ship, before assuming command of the Enterprise. Obviously he did. Any other scenario seems complicated and silly. And more importantly, any other scenario wrecks part of what they tried to achieve in season 1: the "ordinariness" of a future where man travels between the stars and handles wonders with routine aplomb. This might be a vague concept, but to me the idea misplaces the specialness. It re-locates the specialness into Kirk & Spock etc. Kirk is the only one who can be captain of the Enterprise; Spock is the only one who can be XO; the Enterprise has to be the very best ship in the fleet; etc. In the first season, the specialness was located more in that envisioned future, and in Starfleet. Kirk was pretty special, sure; but he was presented as one of a special breed, the starship captain. Maybe the most special captain, but more of a first among equals rather than a destined wonderboy. Later episodes, and god knows the movies, lost this feel. (And maybe I haven't done a good job of describing it to begin with.) (It's also obvious to me that the writer's guide would be a real good source for evidence on the background universe and character backstories, that did not make it onscreen. If it was promulgated by the series creators, and understood as true by all the writers who had episodes made, then it's probably "true" until and unless contradicted by new canon.) A good series of fiction to look into, to get a different idea of how a captain progresses in his career, is Patrick O'Brian's magnificent Aubrey/Maturin books. Those books are a good recommendation no matter what; but in this contact, I think anyone who has read & loved those books, or of course anyone who knows the ways of the Navy, would have automatically assumed that Kirk had at least one other command prior to Enterprise, and that he distinguished himself in that command.