Here’s a Horse and Musket DBA Variant — primarily for Napoleonic and Seven Years War, but since the basic principles of war in that era covered a huge number of conflicts, you could adjust as needed.
Rules: 18th Century
Seven Years War Rules
Richard Bradley of the Tyneside Wargames Club offers a set of free wargames rules for the Seven Years War. The rules are designed for 15mm figures, where a battalion is represented by 3-4 bases.
French and Indian War Skirmish Rules
Richard Bradley of the Tyneside Wargames Club offers a set of free wargames rules for skirmishes in the French and Indian War. The rules have a nice touch with the use of NCOs in command.
Island Mayhem Pirate Rules
Island Mayhem is a set of rules for playing games in which 25mm – 28mm Pirates are searching for treasure.
Beyond the Saale Seven Years War Campaign System
Beyond the Saale is a set of campaign rules for the Seven Years War.