Weapon vs. Armour in Chainmail vs. AD&D

Disclaimer: Note that some of the links below are affiliate links (meaning I get a small percentage of the sale without extra cost to you or the publisher).

Also, I'd like to give a big shout out to waysoftheearth over at the odd74 forum for his insights. My original goal was simply to reproduce his calculations and to be able to compare variations myself — like I do so below.

I have recently talked about some aspects of the man-to-man combat tables in Chainmail (and even shared my calculations so that you can play around with your own variants). It occurred to me that there's a weapon vs. armour table in the AD&D Players Handbook as well (which has been shown to be wildly different from that in Chainmail) — wouldn't it be fun to compare the two?

Here is the weapon vs. AC table in AD&D. As a reminder, these are modifiers added to the to-hit roll with a d20. Armour Class (leaving Dexterity aside) is determined as follows:

For a level 1 fighting-man, the minimum required to hit these AC values is (20 minus AC). so 10+ on d20 hits an unarmoured foe, and 18+ hits someone in plate and shield.

To compare these values to those in Chainmail, we need to cut some of it. The Chainmail tables only include thirteen different weapons, and the armour categories are also different (for instance, chain, banded, studded, and splint mail all belong to the same category). To make things easier, we will only consider the following armour categories: no armour (AC 10), shield only (AC 9), leather (AC 8), leather & shield (AC 7), chain (AC 5), chain& shield (AC 4), plate (AC 3), and plate & shield (AC 2) — leaving out AC 6 for now.

Most weapons in Chainmail have a clear equivalent in AD&D, but note the following:

• for mace and flail we'll use the footman's mace and flail
• sword is interpreted as longsword
• polearms, a single entry in the Chainmail table, are left out because AD&D has different stats for each variant
• lance is similarly left out for now to make things simpler

Edit: I made a crucial mistake in my calculations, essentially flipping the modifiers in AD&D. I'd like to thank everyone who pointed this out! My conclusions are also rewritten to reflect this. Apologies for the errors in the first place.

If we calculate the minimum requires rolls for a level 1 fighting-man with these weapons vs. the discussed armour categories, we get the following:

 

 

And here are the percentile chances of hitting compared to Chainmail:

 

In AD&D the average difference in performance is minimalised; blunt weapons are generally much worse against heavy armour than in Chainmail (cf. mace 20% vs 41.67% or 25% vs 58.33%); and the two-handed sword doesn't vastly outperform all other weapons.

Now, what if we make a direct conversion from Chainmail instead? If we take the percentile values and convert them to target numbers on the d20 scale, we get the following:

Of course, lance and polearms are still too ambiguous in AD&D terms, but it's definitely a starting point. Now, for the last bit, here are the to-hit modifiers for the above, presented in the AD&D format (AC 6 left blank and up for interpretation):

Editable Chainmail M2M Tables

This is going to be a short one.

In my last post I shared some statistics about the man-to-man tables in Chainmail. Here's a link to my calculations, with separate sheets for the numbers as presented in the book and another to play around with (Raw and Mod, respectively). To edit your own version, go to "File" then "Make a copy". Have fun!

On Chainmail's Man-to-Man Tables

On and off I've been working on Láncvért, a supplement for Kazamaták és Kompániák that integrates most subsystems found in Chainmail into the KéK framework in a much less confusing way than the original (at least that's my hope).

One of the many interesting bits in Chainmail is the man-to-man combat system (the one that was supposed to be used with OD&D according to the rulebook, although apparently even the designers disagreed). It's a fairly simple 2d6 table where you check the attacker's weapon and the defender's armour to see your target number; if you meet or exceed your target, the defender is killed (or dealt one die of damage in D&D terms).

Below you can check the table (colour-coded for our convenience); I also added averages (and rounded averages) for each weapon and armour category as well:

The bell curve can be a little counter-intuitive, so I also included a handy chart with percentages. Don't be confused by the colours; I decided to swap them so that red means "hard to kill" instead of "meagre defence" here:

We can already see some interesting things here. For some reason, the spear seems to be the worst weapon in terms of stopping power. Two-handed swords vastly outperform all other weapons (including the mounted lance!), followed by the flail and the morning star.

Leather armour is virtually the same as no armour (it only makes a difference against a dagger or a sword). Shields, however, are really good. In fact, if you have to choose between picking up mail armour or a shield, you should go with the latter.

I also made some more detailed comparisons between various armour types:

Curiously, mail armour makes you more susceptible to being killed against a number of weapons (possibly because the manoeuvrability you sacrifice is greater than the protection of the extra armour that the weapons in particular can bash through — at least that's my theory).

Shields, if we look at them closely, always improve protection, except in one case: against a halberd and paired with leather armour.

There are more rules that go into this subsystem, of course, but this is the main engine. I quite like the extra differentiation between weapons, but I'm not convinced about the specifics. Further testing needs to be conducted until I find a happy middle ground.