Everyone knows that M*A*S*H was originally a straight-up sitcom before morphing into what we now call a dramedy (drama & comedy hybrid). As it turns out, it wasn't the first one to do so.
That distinction belongs to Jackie Cooper's 1959 series, Hennesey (yes, the spelling is correct), which spent three seasons on the same network that would be home to M*A*S*H, CBS (1959-62). Cooper doubled as executive producer, and that experience behind the camera would prove valuable down the road, as Cooper would later concentrate on directing.
The supporting cast included former silent screen star Roscoe Karns, whom Cooper had befriended when both worked for Hal Roach years earlier, and Abby Dalton, who presumably was posited as a romantic interest for Cooper.
Seeing as how this was out of syndication, assuming it was ever syndicated after its network run, I never saw it, so there won't be a rating. We'll leave you with "Hennesey & the Lady Doctor", with guest star Phyllis Coates (ex-Adventures of Superman).