On Thoul's Paradise, perdustin posted an introduction to "the other little brown book", En Garde! by Game Designers Workshop, the first cape-and-sword roleplaying game.
En Garde! started out as a set of rules for swashbuckling skirmishes, similar to Rapier and Dagger from FGU or Gloire from Rattrap Productions, but as a brief history of the game notes, "The players invented backgrounds to provide a reason for the duels. In short order they had individual characters in an ever more complex setting. The setting took over as the main focus of play . . . "
That setting was a Ruritania of the designers' invention, and not Musketeers-era France as perdustin suggests. That setting would strongly influence one of its successors, Flashing Blades, particularly the rules for soldier characters going on campaign and the existence of gentleman's clubs, an anachronism in the 17th century France setting of the FGU game.
I'm fascinated by the description of how the setting developed. Essentially the early players were as interested in the reasons why their characters were dueling, and they set about creating a milieu of carousing and courtship and soldiering around their characters to give them a motivation to cross swords. I've heard it suggested that En Garde! is more a skirmish game than a roleplaying game - the same criticism often leveled at Boot Hill - but I think that milieu proves otherwise. This was a social milieu rather than the more familiar dungeon/city/wilderness or subsector-full-of-star-systems settings adopted for other early roleplaying games.
I'm looking forward to reading the rest of perdustin's posts on En Garde! which I feel I should mention is still in print.