The Solitary Wargamer offers a set of free English Civil War campaign rules called Home Fires.
The Perfect Captain’s Swamp Fox is a set of rules for American Revolution campaigns.
Pigs and Glory is a campaign game for a Viking campaign.
The DFW Grognards have published a set of ACW Campaign rules.
Niagara 1814 is a scenario book for Blackpowder. As with any book of scenarios, however, they can be adapted to whatever rules set you play