& Blenheim Palace is an unofficial supplement for the popular Black Powder rules.
Rules: 18th Century
Argad Medieval Skirmish Rules
Argad is a set of free wargames rules for skirmishes in the dark ages and for pirates in the 17th and 18th centuries.
The Wolf Who Would Eat The Lion 18th Century Rules
Pendraken offers The Wolf Who Would Eat The Lion, a set of free wargames rules for 18th Century Warfare.
De Bellis Indica DBA Variant For 18th and 19th Century India
De Bellis Indica is a DBA variant for warfare in India in the 18th and 19th Centuries.
Horse and Musket DBA Variant
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.