Simplus Medieval Miniaturis Rules (SMR) is set of free wargames rules for battles in the medieval era.
medieval
To Cry A Joust
To Cry A Joust is a set of free wargames rules for jousting combats.
Are You Being Serfed? Wars of the Roses Rules
Are You Being Serfed? is a set of free wargames rule for the Wars of the Roses. The author notes:
I believe they will give a fast and fun game. We are going to have in the region of 40+ units, 800+ figures on the table and with possibly only 2 players they need to be.
Swordplay Man To Man Skirmish Rules
Two Hour Wargames offers Swordplay, a one-to-one skirmish game with sword, shield and bow.
Making Simple Medieval Wargames Buildings
Terragenesis offers a great photo tutorial for making medieval wargames buildings.