Short answers, pulled from the story.
Jeff Perren stood in the living room of Gary Gygax during the early 1970s as one of the first members to join the Lake Geneva Tactical Studies Association. He worked alongside Terry Kuntz, Rob Kuntz, Ernie Gygax, Mike Reese, Leon Tucker, and Don Kaye for wargaming sessions.
Perren and Gygax worked together to create a new set of medieval miniatures rules called Chainmail after their collaborative efforts. The pair published the first set of these rules in a fanzine for the Castle & Crusade Society known as The Domesday Book.
Early in 1970 the LGTSA purchased a considerable number of Elastolin figures. This acquisition motivated Perren to develop four pages of his own rules specifically for these miniatures.
The physical presence of the Elastolin figures drove the creation of new mechanical systems focused on mass combat scenarios where large groups of figures could engage in battle. Perren used these rules to test how different unit sizes performed against one another during playtesting sessions.