In part 2 of my four-part series on adding War to your campaign (Part 1, Part 2, Part 3, Part 4), I discussed running battles on the tabletop, including how to involve your players and keep their interest. One of the points I made in that post was that, when running mass combat as part of a roleplaying game battle, it is imperative to “find a good mass combat system that works quickly, smoothly, and integrates with your game’s system.” Over the years, many different mass combat systems have been developed for different roleplaying games, especially for the most popular of them all, Dungeons and Dragons. There are plenty of good ones out there, but most of them involve some permutation of standard D&D combat, where there are individual units with attacks with attack bonuses, some version of armor class, and hit points, and you roll for attacks against each other. In the end, this boils down to some form of wargaming, with a series of rolls for individual units, and there is nothing wrong with that. In fact, I enjoy mass combat systems like that. Part of that, however, is because of the type of person and player I am; my wife and I both enjoy playing wargames, so a system where combat is similar to baseline D&D mechanics for individual units isn’t very bothersome.
On the other hand, running different units is essentially running multiple more NPCs in a combat system that can already stretch on and bog down when there are many participants. With higher-level players (and suitably higher-level challenges), adding units to a mass combat where they all maneuver individually and make their own attacks can double the amount of time the battle or session is supposed to take. If you have a three-hour battle session planned, this can spiral out of control into a six-hour session if you’re not careful. Again, maybe that’s fine and maybe you and your players will love that. Not everyone will, however.
With that in mind, I set out to create a mass combat system that could be resolved in a single contested roll, plus some quick math, each turn, while still retaining some individual attributes for units to make armies feel unique and interesting based on the types of troops they have. To my knowledge, there aren’t many (or any) single-roll mass combat systems for Dungeons and Dragons that don’t oversimplify combat to a meaningless level or wipe out the difference in troop types. The difficulty with trying to make a system that is both simple and detailed is that often the two things are mutually exclusive in gaming, particularly when it comes to simulating battles. For example, I love the mass combat system in Fantasy Flight Games’ Star Wars RPG system, and it fits perfectly for that kind of roleplaying game and the system they have built. A single roll each turn, with some modifiers based on what is going on or types of troops, decides what happens with the mass combat each turn. There are tables to reference using the narrative system to help interpret the results. However, I’ve had to house rule and modify it a bit to give the level of detail that makes things interesting when large numbers of troops of differing qualities and equipment smash against each other.
I started with a simple contested D20 roll: the GM would roll for the enemy army, while a player would roll for the allied army. This would occur each turn, at an easily-definable point. Most similar things in D&D occur on Initiative Count 20, so I went with that, specifically after all other Initiative Count 20 events occurred. There also had to be modifiers for each army which would represent the different training, expertise, and equipment the armies brought to the battlefield, I wanted leaders to have an impact, and there needed to be some sort of hit point system that could help define who was winning and losing. I sat down and banged out some quick outlines for how I wanted combat to work, and then created some sample units with which I could run quick playtests. The rules went through three permutations until I was satisfied that the rules worked, made sense, and could last a session.
One important decision I made very early on was that I wanted both ranged and melee fighting to have a chance to shine, so things like the peerless archery of Wood Elves or the staunch melee defenses of Dwarves could stand out, while their comparative weakness in other areas could also be pointed out and exploited. I also did not want to make anything require more than one contested roll per turn. My solution to this was to have combat alternate each turn between a Ranged fight and a Melee fight. On the first turn, the armies would trade Ranged blows, while on the second turn, it would swap to Melee, and so on and so forth until the end of the encounter. The system is flexible enough, however, so that if DMs and players wanted to have Melee and Ranged occur every round and do two rolls, they could easily do so.
I next decided that armies would be built of units. Units combine their statistics together to create the army’s statistics, allowing for the combined arms approach where one type of unit, such as archers, could complement for another type of unit, such as knights, each unit covering the statistical weaknesses of the other. I gave each unit six statistics: Ranged Attack, Ranged Defense, Melee Attack, Melee Defense, Morale, and Strength. The Ranged and Melee stats are the modifiers that the armies apply in the appropriate Ranged and Melee rounds, and satisfy my requirement that different types of units can stand out based on their experience. The Attack and Defense versions of those stats are not, in fact, a sort of “Attack/Armor Class” or any kind of comparative stat. Instead, they represent tactics which the army chooses to adopt. If an army fights defensively, such as defending a castle or forming up on a hill and allowing the enemy come to them, that is represented by that army using the Defense version of their stat in the Melee and Ranged rounds. If an army decides to fight offensively, such as besieging a castle or taking the fight to the enemy by charging, they will use the Attack version of their stats. For example, Dwarves are usually renowned for defensive fighting, but heavy armor and bulky weapons do not normally translate well to attacking. I therefore gave Dwarven units higher Defense stats and lower Attack stats. Orcs, on the other hand, are aggressive creatures who are not disposed to standing around waiting for the enemy, so they have higher Attack stats and lower Defense stats. Morale is a catch-all stat encompassing, yes, the Morale of the unit, but also its armor, general toughness, resilience, etc. It is, essentially, the staying power or the resistance of the unit to damage, both physical damage and damage to the psyche of the unit from casualties. Morale reduces the damage that a unit or army will take. Of note, I decided Morale would be an average across the army, not a sum like the other stats, in order to allow casualties to still occur. Finally, Strength is the health of the unit, its Hit Points. Losing these do not affect any of the other stats, but represent the ability of the army to keep fighting. If Strength hits zero, that army has been defeated. It does not necessarily mean every soldier is dead, but instead that the army has lost the battle. It could mean that the army is wiped out, but just as easily that the army’s morale as broken and they have fled, or that the general has decided to retreat.
The resolution of mass combat each turn is a simple affair. The army building should occur prior to the session, giving both the DM and the players their starting army statistics at the beginning of the session. Each turn, a contested D20 roll occurs, and each side adds the appropriate statistic (Melee Attack, Melee Defense, Ranged Attack, or Ranged Defense) to give them their mass combat Score. The two sides compare their Scores to determine which side has won and lost the mass combat that round. The resulting Difference is the base “damage” that will be dealt to the loser’s Strength. Morale reduces this damage, and the resulting final Difference is how much the loser’s Strength is reduced by. And…that’s it. A single roll, some quick math, a single note of bookkeeping, and the mass combat is decided for the round. The DM can then narratively describe the results of the mass combat to the players, and then everyone can move on to the main event: whatever the players are actually doing.
You can find my Simple Mass Combat rules here, on the Dungeon Master’s Guild. They are Pay What You Want, so feel free to download them for free and try them out. Drop a review or a rating, I’d love to hear your feedback. Also, these rules are easily transferable to any other roleplaying system, not just a D20 or fantasy system. It is very easy to create your own units, so you could quickly draw up some science fiction or modern units and still use the same statistics and rules to resolve your battles.
As always, good luck and happy gaming.