One place that seems not-so-realistic are siege weapons: catapults and cannons. Although siege weapons are by definition meant to be used in a siege (attack on a static fortification), in Chainmail these weapons appear in the basic, mass-scale, open combat section (p. 12-14). I'm very skeptical that weapons such as these were used or usable against units of mobile men in the open field (I can't find any research backing up such use), and I'm likewise skeptical of the timing, range, and effect of these weapons in Chainmail. It seems much more "gamey" and unrealistic than the rest of the rules -- and this is important because, after all, the rules to magic attacks such as fireball and lightning bolt were based on these mechanics (and more generally, the D&D spell system as a whole, plus giant rock-throwing). Today we'll look at the catapults.
For the Hit Area cut a circular plastic disc to the diameter stated above. All figures wholly or partially under the circular Hit Area are killed. (For the effect of catapult hits on other artillery pieces, structures, etc., see the section entitled SIEGES.)Now, here are some questions and observations brought up by this rule section.
Rate of Fire: Light Catapults fire every other turn, and Heavy Catapults every third turn, provided they ore fully crewed and have not been moved during the previous two or three turns, as the case may be. Full crew and reduction in rate of fire for partial crews are shown below:
4 crew -- fire normal
3 crew -- fire requires 1 extra turn
2 crew -- fire requires 2 extra turns
1 crew -- fire requires 3 extra turns
Additional crew above four do not add to rate of fire. Only trained crew may operate artillery.
Arc of Fire: 45 deg. left or right
Indirect Fire: All catapult fire is considered indirect and incurs no penalty because of this.
Cover: Any substantial overhead cover negates the effect of catapult fire.
Method of Fire: The player firing a catapult must call the range by stating the distance (in inches) he is firing and how far left or right the missile is to fall (subject to the 45 deg. arc of fire limitation). A triangulation is then made, with the missile falling along the long side of the triangle at the number of inches called.
Fire Optional: Roll two different colored dice. One color is for an overshoot and the other is for an under-shoot. To decide which number of use you take the higher of the two. Miss is in inches, shown by dice spots. If they tie then the rock lands at the specified range. This method is simple but effective. [Chainmail, p. 12-13]
First of all, how many catapults and crew are being talked about here? Recall that the Chainmail mass-combat rules are at a base of 1:20, i.e., one figure represents 20 men. So are we talking about one catapult at a time, or 20? Is the "crew" mentioned 4 men, or 4 figures (80 men)? An important clue: this section predominantly uses the singular, i.e., "firing a catapult", "the missile", "the rock lands at the specified range". Also, if there were multiple catapults, then reduced crew (perhaps all crew for some of the catapults) should result in reduced strength of fire (at the same rate), not reduced rate of fire. My theory is that this section would make more sense if it was moved to the "Siege" section later on, which is written in terms of singular man-to-man action.
(Aside on the Siege section p. 22-24: Note phrases like "One man carrying a ladder moves at one-half speed..." I think this is best interpreted as an individual man -- hard to see how 20 men or more are required to carry a ladder, etc. Argument against this would be that the Man-to-Man Combat section doesn't start until the following page [p. 25]. Argument again in favor of this is that Gygax largely copy-and-pasted the whole Siege section into D&D's Swords and Spells, except for seeing a need to update these passages from "men" to "figures", e.g., "One figure representing ten first-level creatures is able to carry a ladder at one-half normal speed...", [Swords & Spells p. 23]. Edit: And as pointed out by UWS Guy, the Chainmail Siege rules do in fact explicitly say that "it is suggested they be used in combination with the rules for man-to-man combat" which come later [CM p. 22].)
Secondly, is the area and effect of a catapult hit reasonable? Does a single "rock" possibly effect a 2" or 3½" diameter area (keeping in mind that later on, giant rocks will act as the former, and fireballs as the latter)? Assuming that figures for normal men are on bases 3/4" (25mm) square, then they take up an area (3/4)^2 = 0.5625 square inches. Note that a light catapult affects an area of pi = 3.14 square inches = scale 314 square yards (1"=10 yards) = 5.58 figures = 100 men or more (note rule phrasing "all figures wholly or partially under the circular Hit Area are killed"). A heavy catapult affects an area 9.62 square inches = 17.1 figures = 340 or more men. From one single rock? Highly unlikely! So perhaps that's more argument back for a whole battery of catapults firing in unison, although I don't think that such a thing every actually existed, especially in the open field (and see more below).
Thirdly, is the "Method of Fire", declaring the specific range of the shot prior to measuring (based purely on player distance-estimation skill), a reasonable game mechanic? I recommend that you test this out yourself, because I did recently, and prior to that I hadn't realized how incredibly friggin' hard this was. It's one thing to estimate whether an enemy is inside a 12" charge limit or a 24" maximum crossbow shot (that being a reasonable skill and "fog of war" simulator, I find) -- but calling the exact pinpoint distance of something on the tabletop between 1 and 4 feet away, in two axes, is something entirely different. It's practically impossible!
(Aside: And I'm not even talking about use of the "Fire Optional" rule for range variation. I think there's a serious typo in that section: the phrase "higher of the two" indicates that the most probable result is to shoot 6" short or long, with decreasing probability the closer you get to your target. If the phrase were "lower of the two" then you get a more-reasonable triangular probability distribution sloping away from the target point -- Equivalent to: roll 2d6, for every point below 7 your shot is that many inches short, for every point above 7 it's that far long. Note also that giants function precisely as light catapult rules, referenced here via both Chainmail and Original D&D, so presumably this optional rule is available for them. In fact, that's explicitly re-stated in the Holmes blue-book D&D rules for giants, right down to including what I think is the terrible typo regarding "take the greater" die [Holmes p. 26]. And can this be used for fireball attacks? I guess that's your call.)
But throw out realism considerations, and perhaps these last two dilemmas resolve each other. It might be reasonable gameplay to have catapults given a nearly impossible-to-target mechanic based on player skill (neglecting optional rule above), but counteract that with an unrealistically huge area of effect, in the hope that if you get anywhere near the target, one or more figures may be knocked off by it. Does that make sense? I think probably so. If the catapult/cannon section were snipped out of the Chainmail basic rules and moved to the Siege section, then I think basic Chainmail is a very good simulation, and those siege weapons are a more playful toy-like add-on; and at man-to-man scale, like Sieges and all of the rest of the end of the book. It doesn't seem like killing hundreds of men per shot in the open field is something that real-life catapults were prone to do. Unfortunately, however, much of these mechanics were "baked in" and carried forward as legacy material into several editions of D&D and AD&D (with occasional apologetic caveats: see Gygax in AD&D DMG p. 109, last paragraph).
One final note: While the basic Chainmail rule says that "All figures wholly or partially under the circular Hit Area are killed", this is again only in the context of normal men in the historical section. The rule is modified in the Fantasy Supplement at the end, such that catapults (and giant throwing) only effect the lower-end types such as "Halflings, Sprites, Dwarves... Orcs, Heroes... Ogres, Treants, and Rocs" (up to about 6 hits or so). This excludes the more powerful creatures such as opposing Trolls, Giants, Super-Heroes, Wizards, Dragons, and Elementals.
(P.S. You may have noticed that I took a month off from posting, just because I've been busy. All good stuff: teaching double-length accelerated stats courses every night in the college's summer module; playing lots of Book of War as both playtests and my new favorite pastime. We'll see how regular I am through the rest of the summer.)
(Photo by geekygirlnyc under CC2.)