In 1988, S. M. Stirling sold a novel to Baen Books that was set in an alternate history in which one culture had women as soldiers. Jim Baen told Stirling that that idea was unrealistic; Stirling argued with him. At Baen's request, Stirling wrote up his research in a pretty good article titled “The Woman Warrior, or, Rebutting the Editor,” which Baen (to his credit) published in an issue of Destinies, the “paperback magazine” that Baen edited. Stirling presented several good arguments, pretty thoroughly footnoted; among other things, he noted that women had already successfully served in combat, in various capacities, in many times and places.
(I wonder what Baen would have thought of the US military's recent move to de-gender-segregate combat roles.)
Baen's introductory note to the article started by partly backing down from his original claim (he wasn't sure Stirling had proved his point, but agreed that Stirling was not obviously wrong), and then went on to include this paragraph:
“Now for a funny story. Both I and an editor/publisher from another house had summarily rejected the same medieval-milieu fantasy novel featuring a co-ed mercenary cadre on the grounds that ladies just can't hack it with broadswords, or any pig-sticker less dainty than, say, an epee. Boy, was that author mad. Seems us two New York desk jockies with our ineffable male wisdom were patronizing an officer of the United States Marine Corps.”
A note at the bottom of that page implies, if I'm reading it right, that the author in question was Elizabeth Moon, and the book in question was Sheepfarmer's Daughter, the first of the Paksenarrion books, which was published by Baen Books in 1988.