Society for Creative Anachronism

Founded in 1966; early participants or possibly co-founders include Marion Zimmer Bradley, her sister-in-law  Diana Paxson, Poul Anderson, and others from the Little Men sf fan group. Walter Breen was involved with the group on the West Coast.

A suit against the SCA in 2007 followed a criminal conviction of a chapter in Pennsylvania; this suit mentioned the early history of the SCA, Breen, and MZB.

http://www.prnewswire.com/news-releases/civil-actions-follow-sex-crimes-conviction-of-former-pennsylvania-youth-leader-of-international-medieval-history-re-enactment-group-58029682.html

http://yusefsjournal2.blogspot.com/2012/01/sca-fail.html

Details of the civil suit settlement and aftermath here: http://file770.com/?p=9800