Running Mass Fights in Classic D&D

A common troubling point of DM'ing appears when you run the O/AD&D game, especially in the wilderness, by the book: it's pretty common to encounter bands of malicious bandits, brigands, or humanoids numbering in the hundreds.

What's the best way to handle these cases, and what is likely to happen? I've actually had pretty good luck in these cases, so I want to share it here with you.

Motivation

First, I'll point out that this is something I've been wrestling with for a very long time. In particular, I ran up against this in preparing to run the famous World of Greyhawk adventure, Isle of the Ape. The first encounter has the PC party ambushed by over 250 native warriors, with a minimum barbarian level of 3rd, about 30 name-level leaders or above, and 5 trained giant apes. How to adjudicate that? I had the opportunity to ask Gary Gygax about this on the old ENWorld Q&A thread (21st June, 2005):

DELTA: How did you ever deal with the initial combat with some -300 barbarians of varying high levels in AD&D? (Personally, I had to jury-rig a set of mass-combat rules to handle it.)

GARY: Actually, IIRR the PCs from my campaign popped in, surprised the natives, and offed the main leaders quickly, so the mass fled from them. Then the lads ventured past the wall, got a look at things, and got out of there. I don't recall how they managed it, but they left, returned to attack the shaman and his guards, and eventually some of them faced Oonga...

Now, a few things you'll note here. One is that Gary's rough instinct is that defeating a large warrior band comes down to defeating the leaders. The other is that I refer to "a set of mass-combat rules" to handle the situation, that later became my publication of OED Book of War (see sidebar).  

Evasion

Honestly, this is something I tend to overlook in my analyses, until someone reminds me, but this piece of game rules is very prominent in O/AD&D, and you shouldn't entirely overlook it. If PCs encounter an overwhelmingly large band of enemies, then it's quite likely they can choose to evade and escape completely without any combat. 

In particular, the OD&D evasion chart is specifically biased to make escape easier, the more monsters in the enemy party. E.g., for a PC party of 4-9 people, the chance to escape the upper-end of monster numbers is set at 70%. (Increased in woods, if the enemy is surprised, etc.) Although remember if the PCs are surprised this implies that they're inescapably surrounded by the monsters (Vol-3, p. 17).

A couple notes on that: The exact rules text of the outdoor evasion rules is mangled in both OD&D and AD&D in a way that several details are unclear. Slower monsters can't ever catch the PCs, but by the letter of the rule, the evasion process continues, possibly in an infinite loop forever (see other blog articles for this examination). You'll need to make some reasonable interpretations for yourself to fill that in.

Moreover, the evasion rules are not a panacea to PCs confronting the immense danger of the O/AD&D wilderness. Even in the beneficial case noted above, there's about a 1-in-3 chance that PCs are spotted, cannot evade, and have a 50% chance to be caught by a faster monster army. (With this chance repeated over and over, depending on your interpretation of the rules there.) Conclusions we can make are that the by-the-book O/AD&D wilderness rules are meant only for very high level characters (see stats here) -- or that it's super important to keep a high move rate in the wilderness, to avoid all the galumphing bandit and humanoid hordes on foot.

I'll point out that you'd better explicitly tell your players that this is an option, because the Evasion charts don't appear in the player-facing rules of any early edition (OD&D Vol-3, AD&D DMG). 

Note also that in most versions of the rules, elves and halflings have some special ability to hide from enemies, especially outdoors (see: Chainmail, OD&D Vol-2, etc.). Consider letting those PCs check that chance before turning to the Evasion table for effective members in the escaping party (and thus possibly increasing the chance to avoid: for 1-3 PCs the chance can be as high as 90% base).

If all evasion fails, and you have low-level PCs entrapped by an army of humanoids, consider hand-waving the combat, declaring them captured, and switching the campaign to other PCs until the original group can be rescued, ransomed back, etc.

Ranged Combat

Assuming that the monsters are encountered at long distance, and the PCs decide to engage, then some initial long-distance missile fire may occur. (If evasion is attempted and fails completely, the OD&D text says monsters "will catch" the party, while AD&D says there is a "confrontation" -- I interpret this as being in melee distance, but you might differ.) 

There's an interesting observation on this point in one of my favorite Dragon articles (issue #20, Nov. 1978), by Lyle Fitzgerald, "It's a Good Day to Die (Death Statistics of D&D Players)". In his data, Goblin races at the top of the list, accounting for 10.1% of the 600 deaths documented by player-characters in Lyle's campaign. He writes:

‘Goblin types’, while not being strong individually (although they may have the occasional troll or ogre with them), are usually found in large groups, eager to destroy, and can be encountered practically anywhere or anytime according to the monster encounter tables. Typically, you will come across up to 300 or 400 orcs or goblins, who will proceed to pepper your group with a huge cloud of arrows, wiping out all the low level players and hirelings. Very few higher level players ever get done in by these creatures, however.

Now, I might possibly counter-argue this a bit in that where evidence exists, Gygax specifies a fairly small proportion of any humanoid band as carrying missile weapons -- usually around 20%. In the D&D Monster & Treasure Assortment, the percent ticks upward with dungeon level, but tops out at 20% for kobolds, goblins, and dwarves; 25% for orcs and hobgoblins; 30% for gnomes and gnolls, 40% for bandits (there may be typos here), and 50% for elves (as given in OD&D Vol-2). In the Monster Manual the ratios are 15% for gnolls; 20% for kobolds, goblins, orcs, and hobgoblins; 25% for dwarves and elves; 30% for bandits; and 40% for halflings. 

I should probably write more on that analysis later, but, in summary, I use 20% as the standard proportion of missile weapons among any humanoid group. Looking back to Fitzgerald, the average goblin encounter of around 200 has only 40 missile weapons, and the maximum of 400 has 80 -- e.g., specified as slings in the Monster Manual (and undefined in M&TA).

Then you run into the issue of reasonable long-ranged accuracy, for which I've probably written tens of thousands of words on this blog. At maximum bow-range, hitting an army is certain, but hitting an individual man is impossible -- so a small PC band has a distinct advantage here. I'd let PC missile shots target a random figure in an army at effectively no range penalty; while some significant extra penalty should be applied to the army's shots on PCs.

Looking to Gygax's Swords & Spells rules (a work which is otherwise flawed in significant ways), there are fairly well-considered penalties in this situation for missile fire. If the "target is one rank deep or in order" there is a -30% adjustment to casualties; if the "target is single creature, very large" then -50%; if "target is single creature, about man-sized" then -90%. Perhaps for brevity we might say a PC band of up to 10 people gets the 50% reduction, and we simply disregard half of the goblin shots (so maybe have 20 incoming sling-stones on average). 

At this point what I do is split up the arrows equally to each character or unmounted beast, take a handful of d20's, and go around the table rolling for each in batches. If there are 8 figures in the current example, then that's 2 or 3 shots per character. If the PCs have decent armor, and are being shot by 1-hit-die humanoids, then it's quite likely that only a 20 hits them. I would definitely skip critical hits from Nat-20's in cases like these (further abbreviating the process). I suppose you could have the players themselves roll these attacks and tell you the results, assuming you trust them, to make it even quicker. 

Characters Leading a Large Force

Now we get to engaging in close combat. There are a number of reasons why the PCs might be attached or leading a large armed force of their own. In my games, I've seen this occur when: (a) Players hire bands of mercenaries at the outset, (b) characters have previously defeated a force of bandits and pressed them into service, (c) encounter dice indicate simultaneous merchant bands & bandits locked in combat as PCs arrive, (d) a published adventure sets things up this way, etc.

In this case it does work pretty well to hand-wave the normal types battling the background, and have the PCs face off against the enemy leaders in melee. That's what all those copious notes on enemy leader-types in the Monster Manual are presumably for, right? (I mean, maybe?) And it also somewhat nicely echoes the idea of combat-of-champions in certain older cultures. 

Usually the PCs tend to have an advantage in number of leveled characters in this case -- even if the top enemy character is higher level, the action economy swings things in the PCs favor here.

For the background combat, I mentally apply the Book of War core rules -- every 3 rounds of D&D man-to-man fighting, roll a d6 for each 10 normal men battling; results of 4, 5, or 6 (depending on armor) each indicate 10 enemies down. Easy and statistically accurate. 

Characters on Their Own

Or, it's of course at least as likely that you have a small force of PCs on their own in the wilderness. Let's say they opt out or fail at Evasion, survive the Ranged Fire phase, close with the enemy to do combat, and they're high-enough level that hand-waving their automatic defeat is unreasonable.

First of all, if you're running the O/AD&D rules, you'd better honor the fact that fighters get a number of melee attacks equal to their level against normal-type creatures (roughly 1 hit die or less, but varying a bit by edition). So your Superhero (8th-level) fighter is likely going to hew through 8 goblins every round. My feeling now is that this is a paramount point of balance in those editions -- and also likely the single biggest rules difference between O/AD&D and the Basic/BX/BECMI line, where it was discarded. The types of humanoids that appear in numbers of hundreds are precisely the same types that fighters get their mass-attacks against. If you don't use that rule, then arguably you need to dial down the humanoid numbers by an order of magnitude (as was done in Basic/BX, etc.). 

(Hypothetically, I'm not fond of that rule in a design sense, because I don't like hard discontinuities like the normal/fantastic split in early D&D, it slows the game with lots of dice-rolling, etc. And it didn't help me with Isle of the Ape because everyone involved is above 1st level, hence my asking about that specific case to EGG. But it is a core part of the original rules and you should consider it carefully.)

Secondly, terrain is important. When PCs in my games march around the classic Outdoor Survival map, it's quite likely that they're following a path through woods or mountains (which voids chances to get lost). If that's the case, then the main body of humanoids can easily be bottled up, constrained, and dealt with by PCs facing a fairly limited front line. Probably the humanoid army is in a column formation and not well organized to engage in a fight. (I have small d6 charts of other layouts by terrain type that I use, possibly giving advantage to PCs.)

Third, don't forget about morale. It may not be very well defined in OD&D, or commonly used in AD&D, but it's a critical expectation on the part of the system designers. Recall that the kernel of what Gygax wrote in response to my question was that the PCs "offed the main leaders quickly, so the mass fled from them". Make sure you have a mechanic to your taste to handle this (whether from Chainmail, the OD&D reaction chart, the AD&D DMG system, B/X rules, or my BOW morale system of rolling 2d6 + HD and scoring 9 or more). You could possibly apply it to the whole armed opposition, or one unit at a time (foot contingent, archers, horsemen, etc.).

And if you get to this point, you get the joy of narratively describing a fight of epic heroes vs. hordes of enemies in the way that delights your heart the most. The fighters may wade in with their mass-attacks directly, or come up with other creative responses. I've had PCs with super-strength (from a spell, gauntlets of ogre power, etc.) go up hills and roll down boulders, throw trees to block a path of charge, rip off castle gates, etc., and that's all wonderful. 

Magic-users, of course, get to unleash their best area-attack spells. My interpretation of areas in OD&D is that spells like fireball or lightning bolt can only eliminate up to 10 enemy characters at a time -- but by-the-book it could be 40 characters or even 360 if you let the area expand feet-to-yards outdoors (which Gygax clamped down on later, and in Swords & Spells wrote another ad-hoc rule to limit total damage of such spells: example in the book has a 10th level wizard killing around 40 orcs with a fireball maximum, scaling downward for lower levels). A death spell or a conjured air elemental in whirlwind form could be even more devastating. 

But other options could be using illusions (wand or phantasmal force) to create fake allied units and confuse the opposing army -- maybe wasting a round of mass missile-fire (in fact, that was the origin and etymology of the phantasmal forces spell in Chainmail). Or perhaps targeting mind-control powers like charm, hold, or feeblemind spells against the enemy leaders might be more effective. I pretty much always allow the enemy leaders to be identified and targeted in this way (and likewise assume enemy leaders can target PCs the same way, including fighters in swirling melee) -- more than once an engagement with an enemy force has ended without mass casualties, due to the commander being ensorcelled and told to just walk away. There are lots of options here.

Conclusion

For a mid- to high-level party in classic D&D, there are many possibilities when confronting a mass brigade of armed opponents. They can evade the encounter, bring their own armed troop, probably withstand any mass ranged attacks, and then bring super-powerful attacks to bear in fighter whirlwind-melee and wizard area and mind-bending magics. That's not even considering the option to parley, which I've ignored here (OD&D says monsters automatically attack except in unusual cases, which I've assumed by default). My best experiences have been running things purely narratively without a board or map; this is an occasion when using the "rule of cool", bouncing off player suggestions, and giving at least some chance for effectiveness, can solve a lot of problems for you. 

How has running mass combats in D&D worked for you in the past? Any tips or tricks I'm missing here?

This blog post was chosen as the Wandering DMs Patrons' Pick for February 2021. If you want to get in on future polls for things you'd like to see here, join the Wandering DMs Patreon. We thank you for the support!