What is the exact line?
Gary told me that you've been friends since he joined the service, that you asked for him aboard his first command.
If the
Enterprise is his first command, wouldn't have she said
Enterprise? I am of the opinion she would have. She didn't. She said first command. The implication is that there have been other commands. The number of commands was never stated in the canon; it was stated in TMoST that Kirk's first command was a destroyer.
I know that some of you will argue semantics, and I am expecting this, but know this - I am reading what she said literally. I see nothing vague in her comment. What I do see is people relying on ideas that arose later - ideas such as Kirk becoming the youngest captain to serve aboard a starship and that this was his first command. This idea became fixed in the ST Chronology and on the Star Trek website.
I think the thing to remember is that in the time of the first series was that starships weren't a dime a dozen as they became in the later series and movies. They referred specifically to one class of ship, identified as the Starship Class (aka
Constitution-class), which were considered the top-of-the-line vessels. They were small in number, and captains had to earn the right to command such a vessel. These vessels came with additional responsibilities, and had larger crew sizes than other ships in the fleet. This was repeated often in the series, by those who successfully commanded such a vessel (Stone, Kirk, Pike) and by those who failed to command such a vessel (Merik). Kirk earned the command by having commanded an earlier vessel, of which we know little.
I am going out on a limb here for equivalency, but the closest parallel to the situation that was described with the Starship Class ships would be the
Nimitz-class and
Ford-class Aircraft Carriers. To become a captain of an aircraft carrier would be the pinnacle of many captain's careers. All captains of carriers would have served as captains of lesser ships prior to assuming command. Aircraft carriers are the largest ships in the fleet, with each ship like a city at sea, and the captain's responsibilities are greater.
What about Mitchell? We don't know if Mitchell accepted his friend's request - he possibly did accept it. We do know that Mitchell did serve under Kirk on the
Enterprise.
Summation: Dehner didn't say
Enterprise - she said first command. The
Enterprise is an unique ship - a very special ship - that wouldn't be given to a newly promoted captain. For that person to earn the command, they had to prove themselves, which Kirk did on an earlier command. A source that was in contact with the production team would later identify this ship as a destroyer.