http://boards.straightdope.com/sdmb/archive/index.php/t-353422.html
http://www.stjoan-center.com/Trials/
dead link:
http://66.102.9.104/search?q=cache:xbKNeh-e5CkJ:www.hup.harvard.edu/pdf/HOBTRI_excerpt.pdf+&hl=en
What they don't/can't document but has always been rumored is that after Joan repented and had been forgiven she was not released from irons and her guards repeatedly assaulted and/or raped her until she relapsed to wearing mens' clothing, which triggered the subsequent proceeding leading to the death sentence.
Human beings are capable of great cruelty. They are also capable of believing amazing things, as this fellow documents. :-))