Arofan Gregory offers Republic and Empire, a set of free wargames rules for 19th Century warfare.
Gregory writes:
These rules are intended to be used for any land conflict from the Napoleonic Wars through the Second Anglo-Boer War. Encompassing both colonial actiosn and conflicts between technologically advanced powers, they are intended for those who wish to recreate the lesser known conflicts of the period, for which specifically tailored rules sets are often not available. They are designed as a framework that is easily modified to fit the specific situation being recreated. Alternately, these rules are good for those who wish to play battalion-level games that move quickly, as a change of pace from more complicated games … Toward this end, any consistent basing system can be used …