The Source of the Chainmail Cover Art

It is widely known that much of the art that graced games of the 1960s and 1970s derived from prior sources. The original cover of Dungeons & Dragons came from a panel of the comic book Strange Tales #167 (which I reproduce in Playing at the World). Don Lowry, who published the Guidon Games line of rules and frequently provided cover illustrations for the International Wargamer, also drew on pre-existing pictures: as we see here in perhaps his single most famous drawing, the cover of Chainmail. The original appeared on page 114 of Jack Coggins's self-illustrated The Fighting Man (1966), at the start of the chapter "Crescent and Cross" about the Crusades. Gygax mentions this volume in Domesday Book #7.

Armor Class in Chainmail

The man-to-man combat system of Chainmail contains a number of elements that anticipate but differ from  Dungeons & Dragons. As originally specified in the first edition of Chainmail, the chance to hit in combat depended upon both the sort of weapon used by the attacker and the type of armor worn by the defender. This led to an accuracy system that may seem counterintuitive in hindsight - a halberd, for example, is less effective against a target in no armor than it is against one attired in chainmail, presumably because the unencumbered defender can dodge more easily. When Gygax added a table for bowshot in the August 1971 issue of the International Wargamer (about four months after first edition Chainmail), he provided a more recognizable precursor to the Dungeons & Dragons concept of armor class. This same table would eventually turn up in the second and subsequent editions of Chainmail.