After Queen Isabella set up here sisters-in-law (Margaret, Blanche, and Joan) for adultery, this is what happened:
Under torture, both brothers [two knights who apparently had been sleeping with Margaret and Blanche] gave details of the affairs and implicated Joan. The princesses were ‘interviewed’ but not tortured; confronted with the d’Aunay’s confession, Margaret and Blanche confessed; Joan continued to express her innocence. They were brought before a tribunal and found guilty. Margaret and Blanche were stripped of their clothes, dressed in sackcloth and their heads shaved. It is uncertain if Joan suffered the same punishment; the tribunal did not find her guilty but neither did they acquit her.
The women were taken to Pontoise in the north of Paris. There they were made to witness the d’Aunay brother’s execution. Phillipe and Gauthier were castrated and their private parts thrown to the dogs, then flayed alive; molten lead was then poured onto their exposed skin, their bodies strapped to a wheel and their bones broken with iron bars; they were then finally decapitated. Margaret and Blanche were sent to the imposing castle of Chateau Gaillard. Margaret was imprisoned in a high tower, open to the elements, given neither clothing nor bedding and little food.