Champs de Bataille is a set of free wargames rules for ancients based on DBM. Each unit represents 125 to 250 cavalry or foot; more if a warband. The game is designed to be played on a hex board.
Link (direct download)
Miniatures Rules
La Felissima Armada Naval Rules
La Felissima Armada is a set of free wargames rules for naval skirmishes between England and Spain in the Elizabethan Age.
Battle of Granicus
The Junior General offers a set of fast play rules as well as paper figures for the Battle of Granicus, in which Alexander The Great took on the Persian Empire.
Advanced Virtus Ancients Rules
Advanced Virtus is a set of free wargames rules for ancient warfare. They’re described as “fast and furious.”
And One For All
And One For All is a set of free wargames rules from Eureka Miniatures for swashbuckling adventure in the tradition of the Three Musketeers.