This is my answer to a Secret Santicore request.
Dear Secret Santicore…
For my Secret Santicore, I’d like a simple sub-system that allows me
to run a skirmish-type battle with a couple dozen combatants (not
hundreds, like this).
I ask because I recently had a large skirmish, without enough figures
or handy white-board space, and even with the players keeping track of
half of the stuff, it still took an hour and a half to complete.
Sadly, I got flooded with work recently and didn’t have the time to play-test this, but hopefully it’ll only need a few tweaks.
The main concept is to abstract groups of combatants (or even whole platoons) into a single NPC with appropriate abilities. It’s written for D&D, but is probably system-independent.
Mass combat (<100 soldiers)
- You group the combatants on either side (not counting PCs) based on their HD (or level), AC and class. Add the group’s health into one number (each should have the same health, to make keeping track easier, though you could average the total). Add their damage dice into one pool as well (they can mix and match melee weapons or ranged weapons, bot probably not both).
- You roll initiative for each group (and the PCs) if you’re using individual initiative. This order doesn’t get re-rolled, until someone new enters the fray (reinforcements).
- When rolling to hit, consult the opposing groups’ list to see if any AC has been hit (you should probably do this when rolling for a group, not a PC, because the PCs’ position might matter).
- Roll the attacking group’s damage pool, subtract from the defending group’s health.
- If the health of the group drops below an individual member’s health, he/she is dead. Remove his/her damage die from the pool.
- Groups shouldn’t attack PCs, as they are a less abstract part of combat. Separate an individual from the group and let him/her fight the PC. (Don’t forget to lower the group’s damage pool for that round).
- You can vaguely keep track of positions, but I advise against it.
Large scale combat (>100 soldiers)
- Say, you have two armies of organised soldiers with the same training and standard equipment in each.
- Every group of the same type (cavalry, archers, infantry, magi, clerics) is represented by a single character. Separate groups like earlier in mass combat.
- Their equipment is the equipment shared by every soldier in the group. Their health is the number of people present.
- Group damage is 1d10 x (number of attacking soldiers left / 10). Consider causing (number of attacking soldiers left / 10) damage even on a miss.
- Resolve combat as normal, or abstract it further by using the mass combat to-hit rules (damage the group with the worst AC on a miss). Morale checks are especially useful.
- Keeping track of the position of groups is more realistic in this case.