BATTLESYSTEM was mentioned in some of the early literature. Did anyone use it? We never did and I don’t think it’s really available anymore. How did it work? Was it efficient? If not, how do you run huge battles, or really any encounter with more than a few dozen individuals? I remember an old Dungeon article where the PCs had to face off against large monsters with the help of the slave tribe. For every 10 damage the PCs took, a member of the slave tribe was slain. I thought that was well done.
We use percentiles for large battles. Each discrete unit (kank cav, legionnaires, hoplites, chariots, archers, etc.) would roll d100 at their turn. The d100 would be modified by weapons and training, and then the armor of the enemy. If a 5,000-man unit rolled 50%, with modifiers, that would indicate 2,500 casualties/damage to the enemy. The casualty number would then be divided by the HD of the defender. A unit of 10 HD half-giants would sustain 250 losses. Morale, of course, would be important as the losses mounted.