Re: No female starship captains in the 2250s-60s?
, you don't have any solid basis for that notion. For all we know Number One from "The Cage" could well be commanding her own ship (or beyond) by the time of TOS. And how do we know Lester wasn't in sciences back at the Academy. It has been amply pointed out that what we saw onscreen was but a very small percentage of Starfleet personnel and can't really be taken as a large enough sample. Absence of evidence isn't evidence particularly when the circumstantial evidence to the contrary is stronger.
STAR TREK: 1964-1991, 2013-?