This is another Meston misfire from season 7, another example of not having a good idea and thus dredging up something tired from the bottom of the barrel, without finding a way to freshen it.
When Matt finds a young woman alone on the prairie, who's left a wagon train of females who are headed west to marry wealthy prospectors (yeah, sure), he decides to escort them to see they don't get in any trouble. (One wonders whether this is a legal use of his time as a US marshal.) All the usual stuff occurs, with the men in charge of the wagon train trying to take advantage of the girls, and at least one of the females throwing herself at Matt.
Matt realizes the girls are more likely to wind up in dance halls, than married to wealthy men. (This is the episode's oblique way of referring to prostitution.) Arriving at an Army fort (commanded by the omnipresent William Schallert), Matt suggests throwing a dance for the sex-starved soldiers. The result is not unlike "Pirates of Penzance", with the girls pairing off with unwed troopers. (We are told a nearby minister will shortly "conjugally matrimonify" them.)
It's all a little too "cute" (though in "Gunsmoke"'s understated way), too icky for a program founded on violent nastiness, or most viewers' tastes. There is some good Fred Steiner music, though.