Abbe Papon gives some curious details, hitherto unknown to the public, but as he mentions no names his narrative cannot be considered as evidence.  Voltaire never replied to Lagrange-Chancel, who died the same year in which his letter was published.  Freron desiring to revenge himself for the scathing portrait which Voltaire had drawn of him in the ‘Ecossaise’, called to his assistance a more redoubtable adversary than Lagrange-Chancel.  Sainte-Foix had brought to the front a brand new theory, founded on a passage by Hume in an article in the ’Annee Litteraire (1768, vol. iv.), in which he maintained that the Man in the Iron Mask was the Duke of Monmouth, a natural son of Charles ii, who was found guilty of high treason and beheaded in London on the 15th July 1685.

This is what the English historian says: 

“It was commonly reported in London that the Duke of Monmouth’s life had been saved, one of his adherents who bore a striking resemblance to the duke having consented to die in his stead, while the real culprit was secretly carried off to France, there to undergo a lifelong imprisonment.”

The great affection which the English felt for the Duke of Monmouth, and his own conviction that the people only needed a leader to induce them to shake off the yoke of James ii, led him to undertake an enterprise which might possibly have succeeded had it been carried out with prudence.  He landed at Lyme, in Dorset, with only one hundred and twenty men; six thousand soon gathered round his standard; a few towns declared in his favour; he caused himself to be proclaimed king, affirming that he was born in wedlock, and that he possessed the proofs of the secret marriage of Charles ii and Lucy Waiters, his mother.  He met the Royalists on the battlefield, and victory seemed to be on his side, when just at the decisive moment his ammunition ran short.  Lord Gray, who commanded the cavalry, beat a cowardly retreat, the unfortunate Monmouth was taken prisoner, brought to London, and beheaded.

The details published in the ‘Siecle de Louis XIV’ as to the personal appearance of the masked prisoner might have been taken as a description of Monmouth, who possessed great physical beauty.  Sainte-Foix had collected every scrap of evidence in favour of his solution of the mystery, making use even of the following passage from an anonymous romance called ’The Loves of Charles ii and James ii, Kings of England’:—­

“The night of the pretended execution of the Duke of Monmouth, the king, attended by three men, came to the Tower and summoned the duke to his presence.  A kind of loose cowl was thrown over his head, and he was put into a carriage, into which the king and his attendants also got, and was driven away.”

Sainte-Foix also referred to the alleged visit of Saunders, confessor to James ii, paid to the Duchess of Portsmouth after the death of that monarch, when the duchess took occasion to say that she could never forgive King James for consenting to Monmouth’s execution, in spite of the oath he had taken on the sacred elements at the deathbed of Charles ii that he would never take his natural brother’s life, even in case of rebellion.  To this the priest replied quickly, “The king kept his oath.”