For quite some time now, I have been searching for an easy to use mass combat system for my Old School Essentials (OSE) campaign, Riven Realm. My players, whilst hovering around the 4th - 5th level bracket, have advanced beyond mere monster bashing, and have struck it out as political power players within the local region.
The catalyst for this change in play style is their attempts to thwart the growing hegemony of the shadowy faction known as, the Gilded Eye. Furthermore, the king was assassinated and the southern neighbours, the Sais, blamed for it (the planted evidence was clumsy, but it served its purpose). This led to cross border warfare in both directions and heightened tensions, not to mention a domestic scrabble for power between the leading families.
I found that vanilla OSE is comfortably capable of simulating combat between thirty to forty individuals, but once you get into the realm of hundreds, or even thousands of combatants, there are no mechanics for it. I had a read of the mass combat rules in B/X, and also in Third Kingdom Games' Into the Wild and I utilised them for some combats, but I found them exceptionally crunchy and time consuming. I dabbled with GW's old game Mighty Empires, and whilst I found the rules very playable, they did not translate well into OSE or any form of early D&D games. I muddled through and handpicked the rules I liked, and we had some really interesting wins and defeats that hinged on a single roll of a d20 with modifiers, but I found it all finickity, inconsistent, and it lacked player agency.
On a slight tangent, I've recently been working on producing domain management mechanics for my players, so they can effectively run and develop feudal, mercantile, faith-based, and arcane domains. I've chosen the excellent domain management system from TSR's Birthright setting for AD&D 2e. Birthright was released in 1995 and I played it at the time with my friends and loved it. I still have all the old box sets and domain packs that were released before TSR shelved the setting entirely in 1999. One aspect of Birthright was its mass combat system involving the use of unit cards, a battle map and a cross-reference chart to compare morale markers and attack vs defence margins. It was a decent system, but it was only really usable in face to face games.
My game is run virtually, and so I need something that is easy to understand and use, that meshes well with OSE and Birthright's domain mechanics, and can be played out on a virtual table top in a matter of minutes rather than hours.
I had been percolating ideas about using a simple d6 to-hit mechanic, with a successful hit translating to a wound on a unit. Whilst thinking about this, and how it could easily transfer into OSE I stumbled upon KillChain by Castle Grief. Castle Grief is a small game designer owned and operated by the New Jersey, USA based artist, Matt Killinger.
I found this about ten days ago and it perfectly fits my needs.
KillChain is based on early Chainmail rules, and other offshoots. I'll use the author's own words to describe KillChain's primary objective,
"...to A) further streamline the rules to avoid wargame levels of crunch and B) to avoid the need for miniatures and other wargaming setup and be able to determine the outcome of battles in a satisfying way and using graph paper only."
How does this rules-lite system meet my criteria?
1) To-hit rolls use a d6
2) Armour is described as light, medium and heavy, just like in OSE, and occupies the upper range of a d6 roll to hit - light 4+, medium 5+, heavy 6+
3) The system is abstract enough that it can be applied to units of any size
4) Unit hit points can directly relate to monster Hit Dice
5) The turn sequence mirrors the normal combat sequence in OSE
6) Movement rates are simplistic and easy to scale to OSE
7) Morale relates directly to OSE
8) Terrain modifiers, weapon qualities and optional rules are easy to apply without excessive crunch
I haven't entirely utilised the rules as written. I've adjusted them slightly for my own purposes and to gel nicely with both the domain management rules for military units, and with OSE monster stats. For example, I've tied hit points for units to their experience ratings:
Green - 2 Hp
Regular - 3 Hp
Veteran - 4 Hp
Mounted - +1 Hp
Some units may take a number of hits in a turn, such as ranged attacks and melee attacks. Unarmoured levies are vulnerable, as they have only 2 Hp and are hit on a 3+, whilst heavily armoured and mounted knights are kings of the battlefield with 6+ armour and 5 Hp.
In my setting of Riven Realm, military units number 200 individuals, as they also did in Birthright. The costs of raising and maintaining them closely align to the mercenaries costs in OSE. I've created simple stat blocks for units that can almost be lifted directly from their OSE stats. The following example is for a unit of Crossbowmen:
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The Save numbers come from the Fighter progression chart in OSE. Ranges and Movement are counted in 10 yard squares. The saves come into their own when battle magic is used, or the unit faces area affect weapons or large monsters.
I'm quite pleased with the system of mechanics I now have. I'm working on making VTT tokens for each unit type so that players can move troop units on a gridded VTT map in the same manner they would their character tokens.
Overall, if your looking for a simple to use mass combat system for your OSR game, one that doesn't involve crunch and lots of calculations, then look no further than KillChain. All the art is hand drawn by Matt Killinger. I also heartily recommend his Kal-Arath game setting, of which an expansion is currently live on Kickstarter; there are 19 hours to go at time of publishing this. Think of Conan the Destroyer sword & sorcery style of setting. The artwork is excellent, as is the lore.
