Man in the Iron Mask Dumas also presented a review of the popular theories about the prisoner extant in his time in the chapter "L'homme au masque de fer" in the sixth volume of his non-fiction "Crimes Célèbres". The earliest surviving records of the masked prisoner are from late July 1669, when Louis XIV's minister, the Marquis de Louvois, sent a letter to Bénigne Dauvergne de Saint-Mars, governor of the prison of Pignerol, which at the time was part of France. In his letter, Louvois informed Saint-Mars that a prisoner named "Eustache Dauger" was due to arrive in the next month or so. Louvois instructed
Man in the Iron Mask jailers took – created significant interest in his story and gave birth to many legends. Many theories exist and several books have been written about the case. Some were presented after the existence of the letters was widely known. Still later commentators have presented their own theories, possibly based on embellished versions of the original tale. Theories about his identity popular during his time included that he was a Marshal of France; the English Henry Cromwell, son of Oliver Cromwell; or François, Duke of Beaufort. Later, many people such as Voltaire and Alexandre Dumas suggested other theories about the man