Across the three campaigns, the difficulty level ramps up smoothly, so that by the end of the Samurai campaign, you routinely encounter foot-soldiers who are as difficult to dispatch as bosses were in the earlier stages, and the bosses themselves require some major tactical head-scratching.
Plus there are boss-battles and short gameplay-varying sequences in which, for example, you man fixed projectile-shooters. The Knights campaign builds from tutorial-style beginnings, pitching you into some agreeably diverse situations like sieges and introducing the control system in all its considerable depth. This allows For Honor to purvey a three-part single-player game: in the first campaign, you play as various Knights, then Vikings and finally Samurai.