I'm kind of surprised to realize that I never directly compared the old
Chainmail mass-combat rules to my own, much-simplified,
Book of War rules (available at Lulu: see sidebar). Well, I guess I did just for
missiles, which is pretty easy; but I never analyzed the melee combat rules, which are slightly more intricate. For completion sake, let's review the missile rules assessment:
For
Chainmail missile fire, you batch up the firing troops in blocks of up to 10 or 20, roll a d6, and check a table for one of two possible results (or sometimes only one possible result regardless of the d6 roll). There are three armor classes: unarmored, half armor, and full armor -- which we might broadly correlate to leather, chain, and plate in the D&D system that came later. As shown in the table above, taken as an average, and rounding to the nearest d6 pip, the expected kills per figure firing is appreciably close to 3/6 (50%) vs. unarmored, 2/6 (33%) vs. half armor, and 1/6 (16%) vs. full armor. That's actually identical to what I set in
Book of War, prior to ever doing this analysis, so that's great. (Note that
Chainmail has no range modifiers for mass missile fire, which I now think is a realistic choice.)
So far so good. Now let's look at the melee combat chances.
Chainmail mass combat has a separate, unique chart for every troop type attacking vs. every other troop type. There are three foot types (light, heavy, and armored), and three horse types (light, medium, and heavy). There are also special modifiers for pikes that I'm ignoring here. I would
think that the three weight-classes correlate with the three armor-classes above in missile combat, but I've recently seen original players giving mixed signals about that. In the book, attack levels are given in the fashion of "1 die per two men, 6 kills", or "4 dice per man, 5, 6 kills".
Now, looking at the table above, the results here are not aligned so well with either by-the-book D&D or
Book of War (BOW); the attacker weight classes have significantly different chances to hit and kill, apparently reflecting overall discipline and density, even if we would think they are all "normal men" or something close to it. Let's assume that footmen can take 1 hit, and horsemen 2 hits, before dying, as we do in BOW. Then the Armored Footmen land hits on average about the same as missiles do: about 1, 2, or 3 chances in 6, vs. armored, heavy, or light types. As we've said, that's also approximately what we see in standard D&D or BOW for normal or 1st-level men. But Heavy Foot only land hits about half as often, and Light Foot only about one-third as often. In other words, by collapsing the attack proficiency classes, D&D and BOW give about triple hits to Light Foot, and double hits to Heavy Foot, as compared to
Chainmail (noted in the last column in the table above).
That's not something I would expect to "fix" in BOW at any point. Note that this shift seems also to have been acceptable to Gygax in his later
Swords & Spells supplement for D&D, which does the exact same thing (following suit from the core D&D rule). There is a small percentage adjustment to damage by troop classifications in the Melee Bonuses and Penalties on p. 24: ±10-20% for troops that are non-Regular (Guards, Elite Guards, Levies, or Peasants). But when one starts with only a 1-3 in 6 chance to hit, those percentages never amount to a whole pip of difference on a d6.
As a final thought experiment, let's see how the difference in attack types from
Chainmail would appear when up-converted to D&D. Let's say "Armored Foot" is equivalent to a full 1st-level, Veteran Fighter, with (as seen above) about a 50% chance to land a hit on an unarmored/light foot opponent, and so forth. Then the "Heavy Foot" type is somehow restrained from landing hits, about 25% less likely, i.e., 5 pips in 20; so a -5 penalty, or effectively Fighter level -4? And the "Light Foot" is deficient by about 40%, or 8 pips in 20; so fights at -8, or Fighter level -7? Or we could turn it around, assert some sort of reduction for fighting
en masse generally, and say Light Foot is otherwise fighting as Normal Men, Heavy Foot as 3rd-level Fighters, and Armored Foot as 8th-level fighters. Something like that. Interesting, but probably not something we want to port into our D&D games.
Git yer speadsheet here.