A few weeks ago, I wrote about mass combat rules. Yesterday, I had a fight of the party plus 45 light infantry and 8 war dogs against Lord Baba and his 40 thieves. I wanted to use mass combat rules because last session the party was fighting werewolves and real wolves with the aid of a dozen zombies and it had turned into a lot of dice rolling. At the same time, I didn’t want to use something like An Echo Resounding because I didn’t have units of about 100 each. Thus, I fell back on the old M20 Mass Combat rules I had available. But I wanted to make it simpler. The M20 rules still have a problem: Every damage roll is multiplied by the combat scale of the attacker, divided by the combat scale of the defender, and rounded down. So, I tried a slightly different approach.
Group combatants into units as you like. We had three players and me at the table, so each one played their characters, and a single unit. One had all the war dogs, one had 25 infantry, the other had 20 infantry, and I had 40 thieves, and they all had their player characters and I had my non-player character.
Compute total hit-points for all units. Just multiply the average hit-points with the number of individuals. 40 thieves means 40×3.5=140, 20 infantry means 20×4.5=90, 8 war dogs means 8×11=88.
Combat starts as usual. Roll for initiative, move, attack, and so on. AC, movement rate, morale and saves don’t change.
Damage dealt is multiplied by the combat scale. This models how in larger skirmishes not everybody gets to attack. There are corridors, corners, trees, cover, the press of bodies, whatever. Knowing this table, it makes sense to divide units in particular ways. Thus, we changed the split of infantry units from 20/25 to 21/24 so that both units got a ×6 combat scale for their first attack.
When you're hit, adjust your combat scale. Divide the remaining hit-points by the average hit-points per individual and round up to see how many are still alive. For example, if the thieves have 53 hit-points left, then we still have 53/3.5≈16 thieves (rounding up). The original combat scale of 40 thieves was ×6, but 16 thieves have a combat scale of ×5.
Player characters can “hide” within a unit, granting them their charisma bonus for morale checks. When the unit takes damage, the player and non-player characters are the last ones to actually take damage. All these characters attack as usual, with separate attack rolls and separate spell casting actions.
Spells works as they usually do. We had some sleep spells cast, for example. No problem.
Every unit must make a morale check when it looses its first member, and another when it loses half its members. This is important! Such a unit is considered broken. They will hunker down and disengage. This happened to one of the units following the thieves into their hideout.
A player or non-player character within a broken unit may attempt to rally the unit. Only one character per round may try this. If this succeeds, the unit will have skipped a round, no problem. The unit commander in our game managed to pull this off.
If a broken unit suffers any damage, it will rout. A routed unit must flee the battle field and any other unit in melee range will get a free extra attack with a +2 bonus.
Those were all the rules we needed.
It solved my main requirements:
It still required a calculator to determine the numbers lost after every hit.