Mass Combat 1: What Makes a Good System for a Roleplaying Game?

In many an adventure roleplaying campaign, there comes a time when the heroes' struggle gets caught up in larger politics and warfare. They may find themselves helping villagers to defend against a marauding army; get embroiled in a street fight between rival gangs; or, at higher levels, use their hard-earned treasure to hire a mercenary army and rid the land of a nasty orc warlord.

Scenarios at this scope and scale would be tedious to fully play out, rolling for the hits and damage output of each single figure. This is where mass combat comes in. 

Photo by Thom Quine, CC BY 2.0

Mass Combat Desirables

The irony of developing a mass combat system for D&D was fully apparent to the authors of the first such rule set, AD&D Battlesystem. In the introduction to the first edition core book (1985), Douglas Niles points out that the D&D game developed from the Chainmail system for fighting medieval battles at scale, so this product represents a return to the roots of the game. 

Chainmail itself contained rules for fantasy creatures as well as castle assaults involving individual figures. Indeed, early games at Gygax's and Arneson's tables used the dicey, insta-kill Chainmail man-to-man combat system, before Dungeons and Dragons adopted the more heroic wearing down of characters' hits derived from naval combat. 

However, Chainmail mass combat in relation to Original D&D skirmish combat lacks one property: the ability to directly transfer statistics from the roleplaying game to the combat procedure. Indeed, if mass combat bears no mechanical resemblance to the roleplaying rules, you may as well use any tabletop wargame system, be it Warhammer, De Bellis Antiquitatis, or whatever. 

What we are looking for is scaleability: the ability to simply and uncontroversially convert stats from characters and monsters to the stats of the units they make up. This goal is compromised when complicated equations and statistics intervene between one layer and the game and the next. Ideally, you want your units to have Armor Class, hit bonuses, hit dice/points, and movement rate on similar scales to the stats for their constituent figures.

A particularly tricky part of scaleability is the mixing of individual characters such as leaders, wizards, and heroes with masses of troops. You want your system to not just handle battles as a spectator sport, but to actively involve PC participation. The role of individuals in a mass wargame is likely to be abstracted, as a commander token with +2 morale and 3 command points, or an embedded hero who gives +1 to the attack roll. Players, however, will want to see their characters embodied, with access to the familiar set of combat moves and tactics. 

This simulational seam can be finessed, somewhat, by playing out the wargame abstractly when PCs remain in a purely command role, but then zooming in to standard D&D rules when the PCs themselves make contact with the enemy. However, using this method, it might not be clear how the PCs' kill count transfers back into the play of the larger battle. How does eliminating eight knights out of a unit of 100 affect the morale and cohesion of that unit? A satisfying mass combat system for D&D will integrate individual and mass levels organically.

There are other traits that you want the mass combat system to share with other wargames. You could adopt a "power grinder" approach where you feed in troop totals, armament, morale and other factors influencing the battle, then make a single roll that tells you which side won and with how many casualties, like the venerable old computer game Civil War. But that would lack the desirable trait of incrementality - the feeling that the battle is evolving in stages, going back and forth, and you can see exactly when a command decision, a heroic charge, or a well-placed fireball turns the tide.

Another desirable trait is bounded chance. War is chaos, and you don't want the results when two forces meet to be completely predictable. At the same time, you don't want 100 scrawny kobolds to have any kind of plausible chance to defeat 300 brawny gnolls in melee. If seen as a collection of individual combat outcomes, the law of large numbers gives rather predictable casualty figures. For example, if 100 orcs meet another 100 identically armed orcs in D&D combat, with a 25% chance for each figure to kill its opponent on the first round, then 95% of the time the casualties on that round will be between 16 and 34 inclusive, per side attacking.

However, it's on the larger scale that chance reasserts itself. In premodern warfare the question is not how many soldiers will die, a low number compared to the carnage that 0-level D&D figures can wreak on each other in the space of 30 game seconds. Rather, the question is when one side will break and run. This is where the higher-level resolution of the morale check comes in, even more applicable to mass combat than to skirmish. Included under this heading, too, are factors like the formation of the group, which has important consequences for casualties taken and received but cannot be easily equated to the traits of individual combatants. As with any wargame on this level, unit games need to model the emergent group-level properties of morale and formation alongside raw casualties.

It might be tempting to simply treat a hundred gnolls like a single gnoll, having them swing, take damage, and have a chance to run when wounded using the D&D rules. Eric Diaz at Methods & Madness broached this technique recently, but while it is eminently scaleable, it trades away bounded chance and needs its own rule for morale. At the other side of the range are overly complex or wargamey systems that don't scale to D&D stats or don't allow for PC-level input.

Next post, I'll talk about some of the systems out there that I've looked at or tried in practice. Post after that will be my own offering, recently tried out in a street battle in my ongoing campaign.