Simple Mass Combat - Birthright Style

[Please excuse the re-post. Blogger decided that Edit is synonymous with Send To Memory Hole.]

"Fool! You cannot harm me. I am protected by tons of ferociously loyal ablative meat!"

"Eh? Is he raving about us?"

Our games are getting close to the 'evict Team Monster, take their land, build immense phallic memorials to self' end game stage.  With the spectre of mass combat looming I thought I'd share my preferred swarm fightan system.

This is, in essence, a B/X-ified version of the super-simple AD&D Birthright skirmish system (which appears to be a simplified take on Battlesystem 2E, which in turn was more or less good old Perren+Gygax Chainmail in a party frock).  Some bits and wrinkles come from WFB, others from the general sea of unattributable common references in which all gamers seem to float. BECMI War Machine gets no love; it's naught but a monstrous spreadsheet-requiring mess IMO.

This system isn't set up to cope with magic-heavy combats or packs of monsters with special attacks.  It's meant to resolve what the kind of havoc the non-speaking extras are inflicting on one another in a die roll or two so we can all get back to the cool stuff (i.e. the PCs single out enemy generals, casters or monsters for their personal attention).

Initiative
1d6 each side. Winner chooses whether to move first or second.

Movement
As normal, or per GM discretion.
Units moved in order of increasing agility: infantry > then cavalry > then fliers.

Hits
Treat HD in the group as hp total. Ignore "+n" hit point adds.
So 60 hobgoblins (1+1HD) has 60 HD, as do a unit of 20 F3 (3HD). Ditto a herd of ten rhinos (6HD) or a gang of four Storm Giants (15HD)...

Damage
Damage per Round = HD up to 7 (then +1/2 HD over 7, "+n" to die = +1 HD) +/- opponents' AC

• Multiple attacks/round = +100% to DPR
• Max damage/round >12 = +100% to DPR

Fighting
Each side rolls die, higher wins.

• Winner only adds difference between rolls to the DPR. 
• Loser inflicts DPR only.
• Both sides lose on a tied roll.

HD remaining	Resolution Die
Full to 3/4	1d10
Full to 3/4	1d8
1/2 to 1/4	1d6, half DPR
1/4 or less	1d4, half DPR

+1 to die per 2 combat-relevant spell levels cast by side that round
+1 bonus if side has PC/unique NPCs
+2 bonus (one round only) if ambushing
-1 penalty if enemy has terrain advantage

Engaged Groups
Normal engagement rules usually apply: group engages with group on 1 for 1 basis.  Leftover groups can choose where they engage for maximum effect.
If multiple groups attack one group, roll 1 resolution die per group.  Total the side's dice then compare scores.

Morale
Morale checks per B/X, because 2d6 Reaction Rolls are the path of righteousness. ;)

• Check after losing first round of combat;
  
• Check again at 1/2 starting HD. 
  
• Fearsome monstrous enemies may require a Morale check to charge, or if they charge (no one wants to be the first to face *that*).

What happens:

• Pass one morale check = "Fight on!"
• Pass to morale checks = "To the death!"
• Fail first morale check = shaken (fighting withdrawal)
• Fail second moral check = "Leggit lads!" (rout)

Fleeing Combat
1 unopposed strike (DPR, no dice roll) against routing side.

Routs and Pursuit
Pursuit comes down to relative speeds. 
Base speed in tens of feet/inches +1d6 (+2d6 if cavalry, +3d6 if flying). 

• Fleeing side wins: no damage inflicted. 
• Pursuing side wins: inflicts DPR. 

Casualties
Half of casualties are deaths, the remainder wounded/incapacitated.  Victors can recover their wounded, take prisoners and hostages, butcher their foes, etc.

Advanced
Not really advanced, more 'one step up from basic mutual face-stabbery'.

• Missile Weapons: DPR inflicted automatically.  Melee-armed troops can't counter attack until range is closed.
• Lances or charge attack: double damage 1st round only.
• Reach weapons: double damage if charged.
• Mamuk-riders: archers riding gigantic beasts should be treated as a separate unit of archers unengaged by non-archer troops until their mount is slain.
• Aerial Troops: flying troops should be treated as having terrain advantage vs non-fliers. Fliers can't be pursued by non-fliers if they rout from combat.
  

Sieges
The long slow slog of blockade and barrage aren't covered here.  Consult your GM.

• Sallies: resolve as normal.
• Mining: no reinforcing groups can be added to a combat in progress.
• Escalades: land-bound assaulters roll 1d4 to defender's 1d10 until they win a round of combat; defender enjoys terrain advantage.  Aerial attackers fight as normal.  Yes, this makes escalades a slog requiring overwhelming numbers and a run of good luck.  I'd call that accurate.
• Storming: assaulting a breach should be resolved as normal, with defender having terrain advantage.

Monstrous Creatures and NPCs
These brutes will generally just munch their way through spear-carriers (don't even roll for them, just inflict DPR and describe the carnage) until PCs get in their way.

• Monstrous creatures with special attacks (basilisk, dragons, wraiths, medusae, etc) should be treated as casting one or more appropriate spells each round (flesh to stone, cause fear, fireball, death spell, etc).
• Monstrous creatures with special defences can either be treated as casting spells per round (couerl, troglodytes, etc) or as ignoring mundane damage entirely (shadows, wraiths, elementals, etc).
• Troll units regain 1HD per troll every other round of combat.
• Hydras and similar multi-attacking but essentialy non-magic-using brutes can be fought as a unit in their own right. 

Thoughts?


JOESKY'S LAW Compliance Content:
Not applicable. This post is about mechanics for stabbing large quantities of dudes in the face at once, and is thus already relevant to The Mighty One's interests.

Further Reading
Nine and Thirty Kingdoms on non-mass mass combat
Grendelwulfs Combat Scale mass combat system (simple and elegant)

Pic Source
The inimitable Ian Miller (purveyor of only the finest nightmare fuel) of course.

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Appendix: Examples
(This is just me thinking aloud and getting a handle on relative balance. You'll probably want to skip this entirely.)
Note: the DPR figures used here are exclusive of any modifications from Resolution Dice.

Knight vs. Giant Gobo-Ninjas
30 1HD knights (30HD, AC3, +1 TH, lances)
vs. 12 3+1HD bugbears (36HD, AC6, +4TH, axes). 

The knights will inflict (1+6=) 14 DPR in round 1, 7 DPR in subsequent rounds. 
The bugbears will inflict (4+3=) 7 DPR.

This is likely to be a close fight, with the outcome heavily affected by situational factors (Are the bugbears ambushing or in good cover? How good is the relative morale of the two sides?), or by the luck of the dice.

Phalanx vs. Lucanian Cows
2 9HD war elephants (18HD, AC5, +9 TH, trample 2x2d8)
vs. 100 1HD spearmen (100HD, AC6, +1TH, spears)

The elephants will inflict (8+6 x3=) 42 DPR plus (1+6=) 7 DPR from archers in the howdahs.
The spearmen will inflict (1+5=) 12 DPR if charged, 6 DPR otherwise.

This is likely to be a squash match with Dumbo and Babar curbstomping the poor bloody infantry unless they can either panic the pachyderms or skewer them like pincushions as they charge.  There's a reason that elephants were used as shock troops by any army that had access to them for nigh-on 2000 years...

The Legion of Blue-Nosed Doom vs. Old Ten Heads
A ten-headed Hydra in a swamp (10HD, AC5, +8 TH, multiple attacks, terrain advantage)
vs. 80 Hobgoblin legionaries (80HD, AC6, +2TH, melee weapons)

The hydra will inflict (9+6 x2=) 32 DPR.
The hobgoblins will inflict (2+5=) 7 DPR.

The hobs probably have the sheer numbers to beat Old Ten Heads to death, but they'll lose dozens of warriors doing so.  This type of "No time to wait for the archers.  Drown the beast beneath our dead!" situation is what Morale checks were created for...

Orcs vs. The Mighty Orcgrinder
1 Superhero (8HD, AC-1, +6 TH, sword)
vs. 15 Orcs (15HD, AC 6, +1TH)

Superhero will inflict (6+6=) 14 DPR exclusive of magical effects.
Orcs will inflict (1-1=) 0 DPR

A one-sided 'buzzsaw through raw meat' situation.  The Orcs will be relying on luck alone (the score from their die roll) to come out ahead.  They should also probably roll a Morale check when they see their opponent hove into view (as the Chainmail rule).  Let's face it; he's only leaving that last survivor alive to spread the tale...

Gnawers,shield vs. Gnawers,flesh
10 2HD Ghouls (20HD, AC6, +2 TH, multiple attacks, paralysis)
vs. 30 Berserks (30HD, AC7, +2 TH, never check morale)

Ghouls will inflict (2+7 x2=) 18 DPR.
Berserkers will inflict (2+6=) 12 DPR.

A surprisingly close fight.  Ghoul paralysis (treated as Hold Person cast each round) and multiple attacks will tip the balance against the berserkers, not that they're likely to care less.  In the immortal words of Spoon: "I hope I give you the shits you WIMP!"

End.