The Solitary Wargamer offers a set of free English Civil War campaign rules called Home Fires.
campaign
Swamp Fox American Revolution Campaign Game
The Perfect Captain’s Swamp Fox is a set of rules for American Revolution campaigns.
Pigs and Glory Viking Campaign
Pigs and Glory is a campaign game for a Viking campaign.
American Civil War Campaign Rules
The DFW Grognards have published a set of ACW Campaign rules.
Niagara 1814 Scenario Book
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