Jim Wallman offers a set of free naval wargames rules called La Felicissima Armada. It’s a Spanish Armada naval game designed to use 1/144 plastic ships on the floor.
Tilly’s Very Bad Day is a set of free wargames rules for the Thirty Years War. They are designed as a fast play set.
The Junior General offers a set of rules — and paper ships — for the 1571 battle of Lepanto.
The Junior General offers a set of rules for the English Civil War battle of Marston Moor.
In The Year of One Reed: Final Conquest of the Aztecs is a set of fast play rules for students about the Spanish conquest of Tenochtitlan.