The link between Chainmail and D&D is unmistakable. Chainmail was created by Jeff Perren and Gary Gygax. D&D was created by Gary Gygax and Dave Arneson. Since the two games share a common author, the link is clear.
I understand, then, how it is easy, and convenient, for people to make a leap of logic and suggest that Chainmail is D&D, in its primitive form. This is erroneous.
Chainmail is a set of medieval miniatures rules. It does not contain any of the required elements for a role-playing game.
Conversely, OD&D is not a miniatures wargame. There are some 4E players who assert differently, but I invite them to look past the front cover of the original LBBs and read the text within. They will discover that the use of miniatures was deemed "optional" in the original D&D rules. In addition, the Chainmail combat tables were required, only if the players decided not to use the optional combat table contained within the original LBBs.
I am willing to being corrected on this score.