Jeff Perren was an early member of the Lake Geneva Tactical Studies Association along with Gary Gygax, Terry and Rob Kuntz, Ernie Gygax, Mike Reese, Leon Tucker, and Don Kaye. Perren developed his own rules for Siege of Bodenburg, and shared them with Gary Gygax. Early in 1970, the LGTSA purchased a considerable number of Elastolin figures, which motivated Perren to develop four pages of his own rules for these miniatures which focused on mass combat. Perren and Gygax put together this set of medieval miniatures rules and called it Chainmail for publication in a Castle & Crusade Society fanzine called The Domesday Book. Perren and Gygax also designed the miniatures game Cavaliers and Roundheads (1973), the first game published by Gygax’s company TSR.