|15 Individual Mooks
|1 Small Cohort
|15 attacks, assume 2/3 hit
|1 attack against every adjacent
enemy (say about 5) but with +4
on each roll
|Up to 15 damage dice
(about 1d4 to 1d12, no modifier)
|1 damage die for each target (say
about 5) but +5 to each
|15 separate pools of low HP (say
5 each), i.e., even with 5 HP each,
the PCs will still need to make 15
attacks to wipe the group
|1 pool of low (5) HP, but with -5 to
all damage received. Thus, each attack
that hits must roll a minimum of 6
damage to have any effect. And even
then, it'll be kinda pitiful
|Probably each dead at 0 HP for
|Life prolonged after 0 HP by Death and
|5 HP each × 15 people = 75 total
HP to burn through
|5 HP total + (+4 AC per attack) + (-5
damage each hit) + Death and Injury
longevity = ?? I don't know how to
calculate the "functional HP" but it's
|"If they were attacking
5 PCs, they could..."
|Commit 3 mooks per PC, attacking
each PC 3 times. Assuming 2/3 are
hits, each PC suffers 2d8 damage
|Make 5 attacks at most, but at +4 to hit
and +5 damage each. Assuming each one
is a hit, each PC suffers 1d8+5 damage
Skills:1. Authority: Add R+1 for CHA to command a cohort.2. One Man Army: Add R+1 to attacks and damage against cohorts and take -R damage from cohorts.Equipment:• A war horn or drums that, when played, grants +2 on attacks and AC for a cohort under your command.
• (5th level) Banner: 3 slots, 2 hands, 3Q. Count level as +2 for commanding a lawful cohort. Allies subtract 1d4 from morale rolls while in your presence.
This is the basics of a simple mass combat system, like if you took D&D's existing combat rules and tried to make as few changes as possible to turn it into a skirmish wargame. As for warfare ambitions, I'm afraid that even with large cohorts you probably can't run battles of any greater scale than, say, Viking age raids.
Battles involving the Roman Empire often had thousands of soldiers on each side, but in the "dark ages" (the migration period) they started looking more like dozens against dozens or maybe hundreds against hundreds. For those of you who like a nice, gritty, low-fantasy, game where you feel like Gothic tribes pillaging each other then this should serve all your needs. But if you were looking to achieve Agincourt numbers then you'd need around 30 large cohorts just to represent the English side alone. Probably not a great idea.
I'll come up with a system for true warfare later and it'll abstract things a bit more. But for low-scale, tactical combat in a small area, this system can allow you 1) a cool scene now and then of the PCs getting swarmed by a horde of orcs in the dungeon and needing to figure out how to deal with it, and 2) an early taste of warfare gameplay on the rare occasion they gain command over a small army. But even without combat being involved, PCs may gain command of a cohort of spies, an excavation team, religious followers, etc.
And like I said at the beginning of the post, get comfortable with the idea that starting around level 4, the PCs will have around 15 NPCs under their collective command to start doing more complicated tasks. They have more power to influence politics, more power to deal with their problems with violence, more power to gain a reputation, more power to try ambitious plans that would normally take a lot of man hours, and more power to "be in many places at once," so to speak.