A Harvest of Men (II)

War Week continues!  Yesterday I sketched out the basics of a d20 “war zone” system for determining the course of a large-scale battle, arriving at some tentative base numbers.

Of course, what’s D&D without some modifiers?

A lot of different things can affect the course of a battle.  Trying to be exhaustively list modifiers is almost guaranteed to fail.  Instead, I’ll try to consider the more likely occasions, and come up with guidelines that allow winging the more unlikely ones on the fly.

Leadership

There are two considerations here:  Overall leadership, and immediate leadership.

Overall leadership is the army’s overarching strategy, as determined by its strategist, general, or war leader.  This modifier is equal to the leader’s intelligence or wisdom modifier (whichever is higher) + 1 per 5 levels the leader has attained.  If the leader has a military background and some experience (many fighters and warlords, some paladins, clerics of the god of war, war wizards, rangers or rogues trained as military scouts, etc.), also add 1 more.  Multiclassers still only get +1.  If the leader does not have a military background, cut the total modifier in half.

Immediate leadership is determined by the officer in charge of the unit(s) engaged in battle.  This modifier is equal to the officer’s intelligence, wisdom, or charisma modifier (whichever is highest) + 1 per 5 levels the leader has attained, +1 for military background.  (Unlike the overall leader’s case, there is no penalty for non-military background.)  However, as long as the army is following the leader’s strategy, the officer’s bonus is capped at an amount equal to the leader’s bonus.  If the officer diverges from the leader’s strategy, the higher bonus applies, but this may lead to consequences later — disobeying orders is serious!

Add the two bonuses together for each side, then find the difference.  Apply the difference as a modifier to the target DC (so it goes higher if the enemy has better leaders, and lower if the PCs’ side does).

You’ll no doubt have noticed that civilians are ineffective at running armies with this system, yet can still be effective field leaders.  I chose this because it felt more cinematically appropriate to me.  The “immediate leadership” modifier exists for the same reason — it represents that fictional situation in which a quick-thinking and charismatic subordinate breaks from orders and manages to deliver a victory against overwhelming odds.  If that’s not what you’re after, house-rule the house rule.

I chose intelligence or wisdom for the overall leader because the modifier reflects the overarching strategy the army will follow, a plan that’s been drawn up and distributed.  The ability of the general strategist to inspire the troops doesn’t reflect on the brilliance of his plan, but his knowledge of military tactics, raw cunning, perceptiveness, and intuition do.  For the officer, charisma can have more impact, since he’s in the thick of the fight along with the troops under his command, and his ability to rally them might make the difference.

I’m a little concerned that this modifier might be too complex.  If calculations bog things down in playtesting, I’ll need to revisit it and come up with something a little more streamlined.

Terrain

An army fighting a defensive action from superior terrain has an advantage.  If the enemy is defending, add to the target DC if they benefit from the high ground (good for +1-3 DC, generally), fortifications (+2 for makeshift wooden barriers, +10 or more for impregnable adamantine walls), the presence of a river (+1 if defending the opposite bank), lots of difficult terrain in general (+1-2), or other such advantages.  If the enemy is attacking and the PCs have the advantage, reduce the target DC by a similar amount.

Weather often will not affect the DC.  It’s hard to fight in heavy fog, yes — but that’s true for both sides, so the net impact is neutral.  In some cases, though, weather might favor one side (usually the side concentrating on defense).  A recent waist-deep snow will make it easier for archers on a wall to pick off the barbarians attempting to charge that same wall, for instance.

Resources

The presence of powerful magic or monsters in small quantities doesn’t alter the average level of the army, but these things can have a disproportionate effect on the combat.  If one side has something truly special in reserve, modify the DC by a point or two.  Likewise, if one army has traits that might impact the battle that aren’t necessarily fully reflected in its average level — for instance, much of one side can fly, regenerate, or teleport — then modify the DC.

Mundane resources might play a part too.  In a siege, if the defenders are poorly-stocked, they might take a penalty.  If the PCs’ army has cut off the enemy supply lines, the DC for the PCs’ following attacks might be lowered.  If the PCs are the ones being starved out, the DC increases, since the friendly troops are weakened by hunger.  If the PCs are using good steel weapons and the enemies are armed with crude bronze or stone, the DC should decrease by a point or two.

The PCs’ own powers and possessions don’t affect the DC; instead, they affect the rolls.  That’ll be the topic of tomorrow’s post.

Numbers

If one side has a numeric advantage in battle, then the DC should shift to reflect that.  If the enemies outnumber the PCs by any significant margin, the DC should increase by at least 1.  A 2:1 advantage might net a +2 to the target DC, 3:1 a +3, and so on, up to 10:1 granting +10.  Further numerical imbalances begin to bring diminishing returns; 20:1 might be worth +12, 40:1 +14, 100:1 might be worth +20.  The more lopsided the numbers get, the harder it is to overcome them and triumph.

Of course, for sheer realism, diminishing returns shouldn’t apply, at least not to that extent.  This is another cinematic decision; it allows for high-level characters carving their paths through a field full of low-level orcs.  If I’ve set the DCs right, those high-level characters will be threatened, maybe injured, but not utterly overwhelmed.

Tomorrow:  How PC decisions can influence their rolls.

Related posts:

1. War Week: A Harvest of Men
2. A Harvest of Men: In Play
3. A Harvest of Men (III)
4. War and How to Wage It
5. Fox Magic: Martial Feats