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  • Writer's pictureThe True Crime Edition

The Mystery of the Man in the Iron Mask

During the reign of King Louis XIV of France, a mysterious man was incarcerated in several prisons throughout France and Italy. With scant historical information, the legend of the Man in the Iron Mask would be questioned over the centuries to come.

Man in the Iron Mask depiction via

In July 1669, the Marquis de Louvois sent a letter to Bénigne Dauvergne de Saint-Mars, the governor of Pignerol prison, located in Piedmont at the foot of the Alps. The letter stated that a prisoner named Eustache Dauger would be arriving in the coming months to be imprisoned at the facility under Saint-Mars' appointment.

In the time leading up to the Dauger's arrival, Saint-Mars was instructed to build a cell with many doors to ensure the prisoner could never escape and that the cell was sound-proof.

When Dauger arrived, Saint-Mars was ordered to only visit the cell once a day with food and water and see to any other requests from the prisoner. However, Louvois also said that the man was "only a valet" and shouldn't require much during his incarceration at the prison.

Saint-Mars was also given an order by Louvois to kill the man if he ever spoke of anything of importance to Saint-Mars or the other prisoners. He was permanently masked, and no one ever saw his face.

The prisoner wrote letters that were delivered, but the name "Eustache Dauger" was added to the letters after they had been written. Historians claim that the handwriting is very different from the letters' main text and was likely included by someone else prior to the letters being received by their recipients.

Pignerol prison was full of men who had crossed King Louis XIV and his father, King Louis XIII, during their reigns. Many of them came from aristocracy and included Count Ercole Antonio Mattioli, an Italian diplomat who leaked secrets. The Italy we know today didn't technically exist yet and was referred to as separate republics and kingdoms until 1861 when the Kingdom of Italy was unified.

Italian Peninsula in 1494 via Wikipedia

Another resident was the Marquis de Lauzun, a French soldier and courtier who became engaged to the Duchess of Montpensier without her cousin Louis XIV's permission. There was also Nicolas Fouquet, marquis de Belle-Île, vicomte de Melun et Vaux, who looked after France's finances and was charged with embezzling funds by Louis XIV.

Nicolas Fouquet via Wikipedia

These wealthy prisoners still had servants or valets, and life was similar to that outside. When Nicolas Fouquet's servant, La Rivière, was taken ill, Saint-Mars instructed Dauger to act as Fouquet's temporary valet until La Rivière was well again.

Dauger would assist Fouquet with whatever he needed, with one rule; Dauger was not allowed to interact with other prisoners, especially the Marquis de Lauzun. Historians believe this instruction was created because Lauzun would eventually be set free. Fouquet's embezzlement charge meant that he would never leave the prison, so Dauger's existence could be kept secret from the outside world.

Man in the Iron Mask hand-coloured print via Wikipedia

Saint-Mars had many roles appointed to him across Italy and France over the years. Each time he moved to another position, he took the prisoner with him. In 1681, Saint-Mars was appointed the governor of the Exilles Fort in northern Italy, and six years later, they moved again to Sainte-Marguerite, an island off of Cannes, France. It was on this trip to Cannes that the rumours of the man in the mask began to circulate.

At Sainte-Marguerite, Dauger was secured in a similar cell to that at Pignerol prison, with multiple doors to stop him and his words from escaping.

Dauger and Saint-Mars would make one more move to Bastille prison in Paris, where Dauger would spend his remaining days under the eye of Saint-Mars. No longer acting as a valet, Dauger was confined to his cell and was fed by the prison's deputy, de Rosarges, who claimed that the permanent mask the prisoner wore was actually made of velvet.

Bastille prison in Paris via EnglishClub

The man in the mask reportedly had two musketeers by his side at all times. They were ordered to kill him if he ever removed his mask. It's also recorded that the prisoner was treated incredibly well and received anything he asked for—a different life from that of a valet.

So, who was the man in the mask, and why was it necessary to keep his identity secret? Historians agree that the man in the mask existed, but there are disagreements as to the real identity of the prisoner.



Louis XIV's real father

King Louis XII had been estranged from his wife, Anne of Austria, for 14 years when Louis XIV was born in 1638. It's suggested that the future king was conceived by another man, and Hugh Ross Williamson theorises that Louis' biological father left France but returned to extort money from the royals in the 1600s and was ultimately imprisoned, and this was the mystery man behind the mask.

Anne of Austria via

Louis XIV's brother

Philosopher François Voltaire believed that the man was Louis XIV's older and illegitimate brother. He claimed that the prisoner was the son of Louis' mother and Cardinal Mazarin, minister to the King.

However, Voltaire was also the forerunner for the French Revolution and tried to cause rifts between the royal family and the country's residents. If the family's coverup were brought to the public's attention, the revolution would have a stronger footing to ensure a republican leadership.

Voltaire was a prisoner at Bastille prison in France, where he was incarcerated over a decade after the masked man's death and only spent 11 months at the facility. There was potentially some overlap with long-term prisoners. Voltaire could question the mysterious masked man, as he claimed that the man in the mask played musical instruments and was a refined gentleman, not a servant. In 1771, he was the first person to claim that the man wore an iron mask, in the second edition of his book, Questions sur l'Encyclopédie in 1771.

"The chin was composed of steel springs, which gave him liberty to eat with it on."

The French General

In 1890, French historian Louis Gendron uncovered coded letters written by Louis XIV. He passed these letters to Étienne Bazeries, who used the Great Cipher to crack the letters' code. It took him three years.

Louis XIV via

According to the translated letters, Louis was furious at the French General, Vivien de Bulonde, for abandoning his post at the Siege of Cuneo, where he was in charge of an attack on the Italian border. Louis' letters told the recipient that Bulonde was;

"…to be conducted to the fortress at Pignerol where he will be locked in a cell and under guard at night, and permitted to walk the battlements during the day with a 330 309."

It's believed that 330 and 309 meant "in a mask."

Some historians claim that Vivien de Bulonde is the true man in the mask. In contrast, others question the dates of events and that Bulonde's imprisonment was widely known to deter other soldiers from desertion.

The Valet

Others believe that the masked man is the story of two identities and a mixture of Ercole Antonio Mattioli's wealthy treatment in prison, and valet, Eustache d'Auger's life behind bars.

Legislator Pierre Roux-Fazillac stated in 1801 that d'Auger's master was Roux de Marcilly, the head of a French protestant group. Marcilly was executed in 1669 for plotting against King Louis XIV, and his valet was possibly abducted and put in prison for knowing too much.

In The Man Behind the Mask, author John Noone claims that the French foreign minister may have told Saint-Mars that the prisoner shouldn't be able to communicate with anyone, as he may have seen or heard sensitive conversations while serving his master. Saint-Mars may have interpreted this to mean that he shouldn't be seen, either.

King Charles II's son

King Charles II of England, Scotland and Ireland reigned from 1660 to 1685. Charles II's illegitimate son, the Duke of Monmouth, led a rebellion army against his uncle, King James II, in 1685. The rebellion failed, and the Duke was executed, but in 1768, writer Saint-Foix claimed that the Duke wasn't dead and instead, he lived out his days as the man in the mask because the King couldn't bear to kill a family member.

The Diplomat

Ercole Antonio Mattioli leaked information to the Spanish about the sale of Casale, a fortified town on the border of Italy. Mattioli was working on behalf of Charles IV, Duke of Mantua, who was bedridden.

Lands of Victor Amadeus II featuring Casale via Wikipedia

He took his commission before he was kidnapped by the French and was incarcerated in Pignerol in April 1679, which was part of France at the time.

In the 1820s, British politician George Ellis reviewed several documents from French archives, which referred to Mattioli as The Iron Mask prisoner. Seventy years later, German historian Wilhelm Broecking independently confirmed the same findings.

Eustache Dauger de Cavoye

This Eustache Dauger was a Frenchman involved in the l'Affaire des Poisons, a murder scandal where many members of the aristocracy were imprisoned on charges of poisoning and witchcraft.

The events implicated over 400 elite members of society, and eventually, 218 were arrested, and 36 were executed.

l’affaire des poisons via Wikipedia

Historians believe that this Dauger was the supplier of poison at the exclusive parties. While in prison, it's reported that he poisoned Nicolas Fouquet in his cell. A letter from Marquis de Louvois to the governer Saint-Mars questioned how Dauger got the drugs into prison to kill his fellow inmate.

In 2016, Paul Sonnino, a history professor from the University of California, claimed to have uncovered the Man in the Iron Mask's real identity.

Sonnino believed that the man's name was indeed Eustache Dauger and that he was a valet, but his master was someone else; the treasurer Cardinal Mazarin.

Mazarin was the first minister for Louis XIV and his father before him. He was also the head of government for Anne of Austria and was responsible for Louis XIV's education until he was older.

Though Cardinal Mazarin held important titles, he had accumulated vast amounts of money during his years working for the royal family.

Sonnino discovered that Mazarin had stolen vast money from the English royal family. He believed that Dauger found out but revealed his findings to the wrong people and was imprisoned to keep the secret. Because of the sensitive nature of the situation, he was told he'd be killed if he revealed his identity to anyone.


The man in the iron mask died in 1703 in Bastille prison in Paris, France. He spent 34 years incarcerated, under the watch of Bénigne Dauvergne de Saint-Mars. His death certificate noted the name Marchioly rather than Eustache Dauger.

So, were Voltaire's embellishments of the masked man purely to conjure a French revolt against the monarchy to establish France as a republic? Was the mask simply a misunderstanding?

Or, was the masked man someone of importance who needed to be kept in the dark for the rest of his life?


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