 In his "Memoirs" Voltaire wrote that Charles' death was caused by consuming a meal of death cap mushrooms.Charles' life opus, the Pragmatic Sanction, was ultimately in vain.Maria Theresa was forced to resort to arms to defend her inheritance from the coalition of Prussia, Bavaria, France, Spain, Saxony and Poland—all party to the sanction—who assaulted the Austrian frontier weeks after her father's death.