The PCs can still interact, as generals, with the mass combat rules. I still haven't read these particular rules thoroughly, but in general the point of mass combat rules is to provide a higher level of abstraction for times when details don't matter as much--then you zoom in whenever details matter.
That's when you want mass combat rules, when the PCs are not onscreen. If they are onscreen that's just regular combat against a large number of foes, perhaps using the horde rules.
It's about reducing the number of dice that are involved, and providing enough rules support that the DM can let the players give orders to/roll the dice for "their side." Without mass combat rules, all you've got is DM fiat, which leaves no way for players to be involved at all.
The bolded part explains why it seems we are in disagreement then. The math of these rules is so insanely out of balance with what you would expect to happen or matter, that it makes your proposed scenario not work.
A minor difference (20 BR) is all it takes to assure victory. So I’m thinking to myself, perhaps I’m being harsh, and this is only meant to be used when units are relatively close in power.
Let’s take a horde of orcs, led on a holy war by their warchief, against… well guards don’t work because @ CR 1/8 they’ll be destroyed by the superior orcs, so let’s go with Thugs or Scouts, your choice, led by a Veteran.
399 orcs, 1 BR per 5, so 1/5 BR is 80, plus the CR 4 Warchief brings us to 83.
399 defenders, 1/5 BR, 80 plus the CR 3 Veteran gives us 82
These guys are neck and neck, and we’ll assume equal moral and no walls or other structures to give one side advantage.
They both roll. One of two things is about to happen, either one will roll 10 or more than the other, deal 5 damage to that 80 plus hp, and then that defender fails a DC 10 morale roll and immediately dies or the confrontation will end with only 2 or 5 damage done.
How long do you think it will take to work out this combat? If we assume DC 10 moral checks are automatically made (not difficult with a few modifiers like “the battle is important” and “I’m well equipped” along with a +3 charisma on our leader figure) then if they deal max damage every round to get to the 40 damage they will need to get the DC 15 morale check will take 8 rounds of combat.
If they only deal damage 2 at a time, that becomes 20 rounds of combat.
And, that Veteran army we keep throwing around has a BR over 800, meaning you need to do 400 damage to them to break them. That is 80 to 200 rounds of combat.
The PCs can only be in one place at a time, and nobody wants to sit around doing nothing while the DM rolls five thousand attacks that don't involve the PCs.
I couldn’t agree with this more. And at it’s most intense, where the die rolls actually matter instead of just being a formality, that is exactly what this system seems to be.
400+ modifiers are indeed silly. Here's my attempt at revising the rules from
http://media.wizards.com/2017/dnd/downloads/2017_UAMassCombat_MCUA_v1.pdf:
(1) Every mass combat turn takes 10 minutes, not 1 minute. (This is an aesthetic choice to make battles feel right; choose a different timeframe if you prefer.)
(2) Use everybody declares/everybody acts resolution, like BattleTech or AD&D, instead of turn-by-turn resolution. This is important for resolving battles.
(3) There is no Attack only, only a Fight action. When a unit Fights another unit, both of them are fighting and either one can take damage. See below.
(4) Resolve movement before resolving Fights. You don't need to Disengage unless you were already adjacent to the enemy at the beginning of your turn (during action declaration).
(5) When a fight occurs, you total up the BR of all allies involved in the Fight on each side, and roll
3d6 * (BR/100, not rounded). The enemy units in the fight must lose that many BR--the enemy commander(s)/players can allocate the losses wherever they chose. Whoever loses the most BR is the loser and must make a morale check or disband and be destroyed. There is a cumulative -1 penalty to the morale check for every 5% casualties the unit has taken.
Example: If 200 BR of dwarves are Fighting 300 BR of Yetis while 150 BR of elven archers fires arrows at the Yetis, the dwarves and the elves roll 3d6 * 350 and the Yetis roll 3d6 * 300. If the elves and dwarves roll 11 and the Yetis roll a 12, then Yetis lose (11 * 3.5) = 38.5 BR, rounded down per usual 5E rules to 38. The elves and the dwarves lose 12 * 3 = 36 BR, which the dwarven commander allocates to the dwarves (because that makes sense, since the elves aren't in the melee and Yetis don't have spears). The DM is playing the Yeti commander and allocates all 38 BR to the Yetis. Since the Yetis took more BR damage, the elves and the dwarves win the field, and the Yetis must make a DC 10 morale check at -2 (they've taken 12% casualties) or be disbanded. The DM rules that the Yetis are normally Stalwart (+4), so the Yetis roll at +2 total. They roll a natural 14, for a total of 16, and remain intact. The Yetis and the dwarves will continue to fight next turn.
This works significantly better. I may just steal this for my own use.
If I understand correctly, BR is not like HP. The goal is not kill all the enemies by wearing units down to zero. In fact, "a unit’s BR can be reduced by being attacked, going as low as 0 or a negative number."
The purpose of the combat is entirely to reduce morale and then force morale checks to get units to flee. This was not obvious to me at first.
I guess this is where chance comes in, though it will still only be one side making morale checks if the BR of the units is more than 20 apart.
Problem is though, any well maintained army is going to have at a minimum a +6 mod on a DC 10 check.
Or, we give them a +0 and any unit disbands, flees and dies with first contact with the enemy
Either Morale removes the need for the combat, or the combat will drag on longer than any other fight in 5e, with less interesting choices for the players to make at any point
