*The contents of this post have not been playtested. Consider this a brainstorm. I am not a historian.*
Gundobad does well in establishing their goals for a mass combat system, and I will try to do the same. I'm looking for a system that:
- focuses on forces between 30 and 200 strong
- works with, not replaces, existing combat rules
- easily allows major characters to have major impacts
- is very dangerous
- is inspired by, but not beholden to, ancient historical combat.
- is inspired by, but not beholden to, ancient romanticism about combat.
The battle cry concept is directly transferable. I would use the commander of a force's charisma, to emphasize the larger-than-life personality of many battle narratives. (No leader? Go last in the initiative order.)
Larger forces should have greater capacity for damage, and be more resilient. We'll say each force one standard attack against other forces for each ~20 combatants it has. Maybe starting HP is straight up equal to the number of combatants in a force. You can never more than double the number of attacks against a force that it can make; there's not enough room.
Damage based on weapon use can work, but there should be some contingency for combined arms. The multiple attacks in a turn should represent the weapon composition, and influence what maneuvers are possible.
- light weapons (slings and sidearms) 1d6 damage
- medium weapons (spears and khopeshes) 1d8 damage
- heavy weapons (polearms and greatclubs) 1d10 damage
Defenses probably need to be changed. Armor should still be relevant, so the average Block score of the unit can be used. Rather than Dodge, we can substitute something like cohesion, a representation of how well the force holds together, scored up to six.
- barbarian cohesion -2
- average cohesion 0
- trained cohesion 2
- veteran cohesion 4
- hivemind cohesion 6
Individual maneuvers are probably too small-scale, as are normal combat rounds. One mass combat round should represent multiple minutes. Formation maneuvers should have some hope of efficacy, and can be commanded by the leader of the force. (No leader, no maneuvers)
HP, despite its name and inconsistency in fiction, could be a surprisingly good fit for mass combat. We'll say that HP = number of people in the force, but losing 1 HP doesn't mean someone dies. A military unit can sustain surprisingly few casualties before a rout. Its combat efficacy might not actually degrade very much before breaking, and that is an interesting dynamic I would like to emulate. We can recast HP as morale or discipline, and write a quick dismemberment table to represent the outcome of flight, from chaos to rout. Roll 1d12+negative morale:
- 1+: Chaos. Get -4 to cohesion and maximum morale for X days.
- 11+: Flight. Force immediately attempts escape, no longer making attacks. Orders given to aid in escape will still be followed. Force commander can spend the force's turn testing 1/2 their charisma to rally.
- 16+: Rout. As above, but no orders are followed. For every round the force is pursued, have the army test dexterity. If it succeeds, d10*5% escape this round and half as many are killed. If failed, D10*5% are killed this round and half as many escape.
I think we should let forces break up and reform if they want. So if there's a force of 100 people, it can split into two forces of 50 people. Splitting into anything smaller than 30 renders those slivers ineffective in mass combat as forces.
For every 25 combatants in a force, there is a champion. These champions may make attacks, cast spells, or take other actions at any point in their force's turn. Unless their action is totally defensive, an opposed champion can target them with their own actions; dueling champions will be common. Player characters who are not champions can still take actions, but not in ways that will significantly affect the entire opposing force. They can take actions that will aid allied champions. Also, this means there will always be at least a couple named NPC opponents.
Being in a battle is dangerous. PCs sticking their necks out can be targeted by opposing forces, which get +2 to hit and +1d6 damage if the danger of "fighting lots of people at once" is not mitigated. This applies to champions as well.
At all times, keep in mind that these are minor skirmishes for a small society. The bronze age Zhou dynasty easily mobilized armies of 4,500 combatants. They were better at logistics than, say, the people of Mesomergos, and they didn't need to answer a giant's riddle to ford a river. When you're trying to keep 100 people fed, military operations are essential. If you are directly on a river, friendly barges will do the trick. If you're not, you have to carry most of your food with you. As a DM, if a PC is leading a battle, by no means give them a strategy-game style assessment of what's going on. Make clear how they know what information they know. Use of a chariot as a mobile command center should be prized. Messengers and scouts should feel invaluable to player commanders.
Fortifications should be big deals. They should limit the total amount of attacks per side, and provide serious defense bonuses. Siege engines are not assumed. If you want to get into a walled city, you have to incite treachery or use a strategem of war. Even if you have large numbers, expect to wait around outside your foe's gates while they go hungry. You have a supply chain yourself, right?
Oathkeeper Albrecht's Levy:
- HP 100. Five STR 12 attacks (three 1d8 spears, two 1d6 slings). Four champion attacks.
- Block 2, Cohesion 2.
- Battle Cry: For the Falcon! +15 (if led by Albrecht)
- Champions: Oathkeeper Albrecht (warrior 3), Xeuin Sworn (thief 1/warrior 2), Janik Sworn (warrior 2), Wei Ning (wizard 2)
- HP 40. Two STR 12 attacks (one 1d6 knives, one 1d6 slings). One champion attack.
- Block 2, Cohesion -2.
- Battle Cry: Your money or your lives! +12
- Champion: Li Shortnarrow (thief 2)
Hypothetical Chapter of Sworn:
- HP 30. One STR 14 attack (one 1d8 spear). One champion attack.
- Block 3, Cohesion 4.
- Battle Cry: A tangled mess of personalized calls +12
- Champion: Han Sworn the elder (warrior 2/practitioner 2)
Uzay's Mysterious Legion:
- HP 200. Ten STR 12 attacks (five 1d8 spears, two 1d10 longspears, three 1d8 bows, two 1d6 slings). Eight champion attacks.
- Block 4, Cohesion 4.
- Battle Cry: a lyrical call and response, referencing events and places you know not +13
- Champions: Khayam (wizard 2), Tendren (warrior 1), Kalo (thief 1/warrior 1), Tendren the elder (wizard 1), Akiar (warrior 2), Calormon (dreamer 3), Shasa (witness 1), Luszi (warrior 2)