Earlier, I mentioned Philotomy's Musings, a pamphlet designed for original Dungeons and Dragons. In my search for a re-statement of Chainmail, I also came across Forbidden Lore. Scroll down to the bottom of the page, and you will find a pdf copy.
Forbidden Lore is a free, 16-page booklet, authored by Jason Vey of Elf Lair Games, and designed to clarify and bridge the combat rules in Chainmail and original Dungeons and Dragons.
Even if you do not own Chainmail and original Dungeons and Dragons, this pamphlet is well-worth a look: it quotes from the original documents, and makes some compelling arguments about the relationship between those two early rule-sets.
Chainmail includes three competing and largely incompatible combat systems: one for mass-combat, another for man-to-man combat, and a third for fantastic combat. The author suggests (and quotes liberally from original D&D to evidence) that all three combat systems should be used, but that use of any particular combat sub-system depends on the situation. An attractive argument, for many old-schoolers, although the rpg game-design history of the last 30 years has been to replace sub-systems with unified systems.
While I have some minor quibbles regarding some of the extrapolations and interpretations Jason has made in Forbidden Lore, overall this is a very compelling analysis of Chainmail and oD&D. This is a valuable (and free!) resource, and should be read by anyone who is interested in the early design of original Dungeons and Dragons.