Treatise on Tolerance is a book written by Voltaire, following the trial of Jean Calas (1698-1762), a French Protestant merchant accused of murdering his son Marc-Antoine to prevent his supposed conversion to the Catholic Church. Calas was executed in Toulouse on March 10, 1762, after being tortured; he never confessed to the crime that completely lacked evidence. Calas was executed largely in response to the reaction of an angry mob and the zealousness of some local magistrates. Struck with the extreme injustice of the case, Voltaire undertook a private and public campaign to exonerate Jean Calas. In doing so, he put Catholic prejudice and fanaticism on display. In 1765, after Louis XV fired the chief magistrate and the case was retried by another court, Calas was posthumously exonerated and his family paid 36 thousand francs.