I asked Michael Dobson, editor of B9, Castle Caldwell and Beyond:
Q: I have a question in regard to your editorial work on B9: Castle Caldwell and Beyond (1985) by Harry Nuckols. One notable thing about B9 is that, unlike the other Basic series of modules, B9's adventures are based in locales which are not clearly tied to the Known World setting. The kingdoms of 1) Princess Sylvia, 2) Prince Frederick, 3) Oliver's home town of "Hom", and 4) the enemy kingdom of "The Great Escape" adventure, are found nowhere on the map of the D&D Known World.
Michael Dobson: Here’s the story on B9 Castle Caldwell as best as I can remember. Unlike most modules, this wasn’t done by in-house designers or people in our usual freelance network, but sent in unsolicited. Bruce Heard was our product acquisitions guy, so he would most likely know more about the author. We didn’t have a lot of Basic D&D product coming in, so it was a welcome addition to the line. I liked the fact that it consisted of very short adventures, and felt it would work well for someone’s first campaign.
At the time, the Known World setting wasn’t mandatory for D&D product. My module X10 Red Arrow, Black Shield was, I think, the first serious attempt to develop the Known World environment. When I later became head of games development, I pushed for the Gazetteers product line, which Bruce Heard led. There was, if I recall, some retconning of B9 that took place when the original B-series modules were anthologized (B1-9 In Search of Adventure), to incorporate all of them into the Grand Duchy of Karameikos.