Parsing the Chainmail Combat System

The original rules for Dungeons & Dragons claim to be intended for use with the combat system put forth in the earlier set of medieval wargames rules Chainmail, co-written by Gary Gygax and published by Tactical Studies Rules.  Whether or not Gary ever actually used these rules in the context of D&D is debatable, but I believe it worthwhile from both a historical and a potential gameplay perspective to take a closer look at the “intended” combat ruleset of the original game.

As such I have been spending some time between working on my Megadungeon looking over the charts and tables at the back of the book, and I’ve taken the liberty of parsing out a set of algorithms to use to determine the necessary combat odds.  To understand the following, you need to know the basic system.  Whenever a group of men (stands of 20 in the original mass combat system) attacks another, a number of dice is rolled based on the number of men attacking and the types of the opposing units (expressed hereafter as x/y, where x is the number of dice rolled per y men attacking), with each die needing to fall within a certain range to score a kill (or a hit dealing 1d6 damage in D&D). So if eight men are attacking, with a 1/2 ratio, needing a 5 or 6 to kill, 4 dice would be rolled, and every 5-6 would score a kill or a hit (meaning, on average, 1.3 hits will be scored in such an attack).

Now I’m not entirely sure if the actual ratios and ranges required can be reproduced if there is no clear algorithm, so I will simply present the algorithms I have found that underlie the original system and note where there are exceptions.  For my purposes, there are three levels of foot soldiers and three levels of cavalry, light, medium, and heavy, which is a slight deviation from the original terminology.  Here is what I have found:

There are four basic strengths of unit, ranking from A to D, D being the worst and A being the strongest:

  • D includes only light foot
  • C includes medium foot and light cavalry
  • B includes heavy foot and medium cavalry
  • A includes only heavy cavalry

Based on this, mounting a footman on a proper horse appears to improve its combat capability by one step.

To determine the ratio range of rolls required to kill, a few guidelines are:

  • To kill a unit within the same class or a higher class, a 6 is needed
  • For each difference in steps between the attacker and the defender, when the attacker is stronger, the kill-range is increased by one (so a heavy foot attacking a light foot would require 4-6 on a d6 to kill)
  • Foot attacking cavalry always requires a 6 to kill
  • Heavy cavalry is an exception in the original rules, in that in regards to the range it is underpowered compared to the algorithm

To determine the x/y ratio, the following guidelines can be used:

  • Foot cannot have a higher ratio than 1/1
  • Within a category (that is, foot attacking foot or cavalry attacking cavalry) every positive difference in step increases the y value by 1
  • For foot attacking cavalry, if the cavalry is in the same class or higher, y is increased by 1
  • For cavalry attacking foot, if the cavalry is in the same class or higher, x is doubled
  • Light foot are an exception in that they are slightly overpowered against cavalry compared to the algorithm
  • Heavy cavalry is an exception in that it is slightly overpowered compared to the algorithm

For use in D&D, each character can be assigned a Fighting Capability based on class and level (you can use the values given in the original booklets, or use some other system, possibly using the hit dice proposed in the Swords & Wizardry White Box with bonuses being applied to only one die) which indicates how many men he or she represents using this algorithm.  Whether they are light, medium, or heavy foot, can be based on their equipment at the purview of the GM.  There are other, better thought-out guides to using Chainmail with OD&D, but as those mostly require the original rules of Chainmail to use, this guide can supplement or supplant those tables.

I hope the above was clear enough to read. They are basically transposed from my own notes, which were written pretty much for my own reference. I have yet to closely examine the man-to-man or fantasy combat rules.  Ultimately I hope to come up with a separate combat system to plug into the original D&D rules (or their simulacra) based on concepts in the Chainmail ruleset that I can then release for others to use.  I’m not sure yet whether I want to use the Chainmail system or the now-standard “Alternative Combat System” for my OD&D game.  I should probably get on that, as it begins tomorrow.

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2 Comments

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2 responses to “Parsing the Chainmail Combat System

  1. Pingback: Steppin' On Egg Shells

  2. Pingback: This Is Chainmail. This is D&D. | …duck, duck, DIE!!!

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