DMs, how do you do army battles? How do you act when the party fights a huge number of enemies?

Alright, if you're willing to put in the effort, I will tell you what my DM did.

First, he made these cool little tabard things for each of our characters (pic related) along with a blown up map of the land we were fighting in.

Then he made a list of the resources we had gathered over the game. These ranged from high level NPCs, as well as squads of races/cultures we had befriended (like barbarian tribes and local lords).

Then he gave each of these NPCs/squads a power. For example, the good vampire we befriended could charm an enemy unit which would turn them against the enemy, while the barbarian tribe could charge forward and essentially shove an enemy unit. Essentially, they were all turned into spells or abilities in terms of mechanics.

Then he did the same for the enemy army. Made a bunch of squads with their own powers etc.

He then buffed each of our powers to work on a macro scale. For example I was a Warlord at the time, so instead of just inspiring one person to charge forward, I would be able to surge a whole unit forward.

Then our party split up our resources and mechanically we had a normal battle with a bunch of new abilities and spells represented by the squads and NPCs we took with us. There were of course objectives like protect the keep from falling or take out the enemy commander, and rounds were fluffed as minutes rather than seconds.

Got a little messy, but was loads of fun. The sheer effort he put in is what made it great though.

That sounds amazing user! I will try to do something like that.

Ive been using the mass battles system of ACKS - adventurer conqueror king system.

Its works out pretty well, if a bit slow. Its osr so not too complex, just too many "roll morale to see if unit runs" breaking the flow of combat.

[General's Cha bonus or equivalent] + [General's Leadership skill or equivalent] = Unit Points. If you want more subdivisions you can toss in the general's Int. or Wis. mod equivalents as well. If the relative disparity between military technology matters, add that in as well.

If the army is rabble, half this number. If the army is particularly well-disciplined add +50%.

Take the raw size of the army and divide it into a number of units according to how many Unit Points you have.
"Army" (~40k-200k soldiers) has Str. 8
"Corps" (~20k-40k soldiers) has Str. 4
"Division" (~10k-20k soldiers) has Str. 2
"Brigade" (~3k-5k soldiers) has Str. 1
"Battalion" (200-500 soldiers) has Str. 0

Each Unit has a health track; "Fresh", "Ready", "Bloodied", "Crippled" and if it ever drops lower than "Crippled" it is reduced in size and returned to "Fresh" (Army becomes a Corp, Brigade a Battalion, Battalion disappears).

Congratulations, you now have the armies. Now let's figure out how to make them fight.

Cont.

I've got one slated. Attackers are going to win 3/4ths of all conflicts with NPCs, descending to 2/3rds and 1/2 over the few turns of the raid. They'll only actually roll dice and do damage vs the PCs.

I'm not certain how well it will work, but I guess we'll see.

Waiting for cont. user.

1) Resolve any ongoing fighting; this will obviously get skipped on the first turn.
1a) For a given Strategic Position roll 2d6 + Str. of Units + Technological bonus if there is one. Whomever gets higher is the Winner, whomever gets lower is the Loser. The difference in the rolls is the "Margin of Victory".

>MoV = 0, both sides take 1d6 damage
>MoV = 1-2, Winner takes 1d4, Loser takes 1d6
>MoV = 3-5, Winner takes 1d2, Loser takes 1d6
>MoV = 6-9, Winner takes 1, Loser takes 1d8
>MoV = 10+, Loser takes 1d10

1b) If the PC's were involved in the fight and achieved their specific objectives, you can shift the MoV by 1 in their favor.
1c) If there are no enemies contesting the Strategic Point it is under your control and your side gains its bonuses.
2) Each side secretly assigns orders to Units; "Attack Strategic Point", "Rest & Recovery", "Stand in Reserve"
3) All Units resolve their orders;
3a) All Units assigned to "Attack Strategic Point" are moved to that location
3b) All Units assigned to "Stand in Reserve" may be deployed to defend a Strategic Point that was under your control already.
3c) All Units assigned to "Rest & Recovery" roll 1d6, moving up their damage track on a 3+. A Unit cannot recover size this way and therefore tops out at "Fresh".
4) PC's decide at which Strategic Point to exert their efforts, and by what means.
5) Back to the top motherfucker.

Using this framework you can abstract a whole war--each of the above turns representing months of maneuvering and the like--or a single battle (in which case I'd suggest removing the 'Rest & Recovery action'.

You can further give texture to the battle by assigning special bonuses to the Strategic Points (a small fort ablates battle damage, for example, or the Strategic Point "Gullman's Pass" needs to be under an army's control to attack the "Valley of Bones" Strategic Point). You can also typify each Unit, giving circumstantial bonuses accordingly.

Spoiler.

The point of the above system is twofold;
>Players can have an active hand in leading battles, with mechanical effects and important choices.
>Players can dive into combat encounters which meaningfully impact the larger theatre but do not in and of themselves determine them.

Even better, it works for sci-fi, fantasy, or modern day depending on how much meat you chuck on its bones.

I'd love to take credit but it is almost entirely cribbed from Stars Without Numbers, specifically the War Turn in "Starvation Cheap". It also contains some good rules-of-thumb for generating a civilization's standing army and effective war logistics. I'm a fan, if you can't tell.

There it is. Page 52 is the start of creating armies. The War Turn begins on page 66.

We just play Warhammer Fantasy with lighter rules.

You have two major factors mechanically to deal with before you do anything else.

1) Are the players in a position to shape the battle plan mid-battle?
2) Is whatever system and campaign you're playing of the power level that the PCs themselves can engage entire armies?

Personally, I never do 2, and I rarely do 1, because it makes things difficult to control. (And because I don't like high power systems).

Assuming the answer to both is neither, I tend to do a scenes and rounds sort of thing. Say you're doing a 40k Only-warish sort of setup, players are grunts in a large battle with, I dunno, Orks. What you DON'T do is make it a huge-ass combat encounter with zillions of orcs running at them. What you actually do is make it a combination of narrative scenes, brief fights, and punctuate it with other checks and things that the PCs can do to affect the overall battle.

Something like this, that I'm making up off the cuff so it will be crap.

>Players sitting in their trench. Maybe start things off with a small number of Orks attacking them.
>Roll for perception; if they succeed, they notice the Orks are bringing up some anti-tank guns, which will complicate the armored counterattack the IG has in the works.
>PCs can try to attack them while they're setting up if they notice.
>But doing so requires them to leave their trench, which exposes them to fire
>They can try to just dash across, in which case unnamed enemies take potshots at them.
>Or they can try to do something clever to obscure their movements, like throw smoke grenades or creep around on the map to attack from another direction or something.

Keep most of the battle in the "background", it's going on, lots of people are mixing it up, but the PCs don't directly intervene in anything but their immediate area. Have a flowchart of things that can happen and what the ultimate outcome of the battle is.

1/2

Why not AoS? It's the better ruleset desu

If the players are in command enough to be in the pre-battle planning session, not much changes, except they'll probably have a bigger picture of what's going on and you'll get a chance to anticipate their plans because they're actually making them in front of you, perhaps with NPC input. If the PCs are actually in place to make plans in mid-battle on the fly, you should treat various troop contingents as consumable resources, and keep track of which military assets have been sent where and when. Incorporate that into your flow-chart, which will necessarily need to be much wider and more flexible than before. Again though, have a number of pre-determined outcomes to the battle, and select through them depending on what actions the players take.

I abstract the fuck out of it, and focus on the actions of the players as a microcosm of the larger battle.

Choose a few key events- The moment when a battle standard might fall, a chance encounter with a group of elite enemies, a chance to strike at an enemy emplaced weapon- and play out the fight with the PCs. Treat the battle around them as dangerous terrain features rather than specific enemies, and uses the results of those fragments of the battle to influence how the greater whole plays out.

It helps retain player agency and give them a way to be directly involved, and you can still add in a few skill rolls or slight bits of randomisation for the rest of the battle if you really feel the need.

I'm a fan of the "decision tree" battle :

Each battle is divided in phases, with each having several actions to be performed in a limited timing.

Because of limited timing, the players must choose which action they'll do and which they'll let their allies do.
If the players are really quick, they can finish their actions and then decide to assist their allies.
I'll also throw them "surprise" actions that weren't planned during the briefing.

Once the time runs out, I roll a dice to know if the actions the players haven't done are a success or a failure.

Once the time for each phase has run out, the battle is over.
I check what action failed and what action succeeded and, based on the decision tree, it helps to describe to the players how the battle went, what parts were glorious victories, what part were bloody defeats, and how their actions influenced that.

For exemple, a failed delaying action against the enemy's cavalry on the party's part could have led to the archers of their allies being routed, which made the fighting harder and more costly on a part of the battlefield.
Or maybe their success at killing that enemy mage allowed their allies to attack more safely a part of the enemy's line and to break it, helping to snatch victory.

Sometimes, the battle will be lost even though the party did all the actions they were supposed to :
It's just that the actions they left for their allies were failures.
But the success of the party means it's a less bloody defeat and that can be something.

The downside of this method is that you have to plan in advance what's important about the battle.
It's not just throwing thousands of NPCs at the party and letting it slash through it.

Just going to put this out there:

Actual battles looked nothing like what you see in movies and vidja. They tended to be far more cautious, usually only involving a small portion of an army at a time, and casualties were MUCH lower than you would expect if your only reference is modern media. The object wasn't to kill every enemy, but to break their will to fight. Most deaths were suffered by the losing side as they began to rout.

Try this.
>media.wizards.com/2017/dnd/downloads/2017_UAMassCombat_MCUA_v1.pdf

I always use an appropriately scaled war game with slight modification. For instance, in my current D&D 4e game, we are actually playing Battle Lore for large battles. The mechanics here are not very seamless, but the players don't mind so far.

Player heroics are represented tthese ways: 1) I borrowed the civil war command and colors concept of generals and the hex with the players gets +1. 2) We modified the Lore deck and cards to more closely match some D&D mechanics. 3) we regularly 'zoom in' on the action in a given hex, even ones without active combat for exploration, combat or skill challenge/role play scenes.

>casualties were MUCH lower than you would expect if your only reference is modern media
Except Hannibal the Walking TPK

My simple rules:

>split army into factors of 10 (i.e. 800 men is eight 100s, or 39000 men is thirty-nine 1000s)
>get assload of d6s
>each d6 is a unit
>roll d6s like dice pool, threshold for success is based on relative skill of army, usually 5+ but something 4+ or even 3 or 2+ for a really advanced army, relatively speaking (like orcs with javelins versus machine gunners)
>inflict casualties simultaneously, clear off the dead, roll again if armies continue to engage.

It's good for quick n dirty and doesn't put down too much to one roll.

>using 5shit

No thanks. Also note that that system is almost directly ripped off from the Pathfinder mass battle system in Ultimate Campaign, which was also shit. But then it's Pathfinder/D&D so what do you expect I guess.

I make two character sheets that represent the average soldier on either side

The amount of HP they have is directly proportional to the amount of soldiers per army side

then they battle