Other producers have also produced small unit tactical board wargames covering earlier eras such as the Roman Empire, the Napoleonic Wars and the American Civil War. However, with the exception of Avalon Hill's "Siege of Jerusalem", none of these games have met with much success. Note however, grand tactical board war games have extraordinary followings, especially "The Gamers" series of games covering the American Civil War and CofA's "La Bataille" series covering the Napoleonic Wars and the Seven Years' War. GMT Games has also had considerable success with its "Great Battles of History" series. These series though use larger units, usually at the battalion or regimental level.