Chain mail

chain mail, Chainmail, n., p.n. 1. (n.) flexible armor of interlinked metal rings; term does not predate 19th century; often misspelled as "chainmail." 2. (p.n.) rules set for medieval combat scenarios in tabletop wargaming, published in 1969 by Guidon Games, and later by TSR, Inc. [GJ1]
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Addendum (def. 2): E. Gary Gygax was one of the principal authors of Chainmail. He and Dave Arneson later made fantasy-based additions to the rules, which would lead directly to the development of D&D. [GJ1]