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“Call me accursed!” The man whose voice was almost drowned out by the storm was dressed entirely in black, “a sort of phantom, his head covered with a black helmet and a black mask, something terrible to behold”.

In his 1850 epic book, Le Vicomte de Bragelonne, Alexandre Dumas created a captivating image of the man in the iron mask that would go on to inspire countless films and cement the mysterious figure’s place in popular culture. Dumas was inspired by a legend that had emerged almost two centuries earlier.

It told the story of a mysterious prisoner who had been arrested and secretly imprisoned in France. He had spent decades in various dark and damp dungeons, ending up in the Bastille. Closely guarded, he was kept in solitude where no one could overhear what he might have to say, and he was not allowed even to speak his name.

He was guarded by a gaoler who was ordered to kill him if he spoke of anything other than his needs. The gaoler, nevertheless, showed great respect to this prisoner, even standing, hat in hand, in his presence. For, in Dumas’ story, this was not just any prisoner: he was one of the highest-born men in the land.

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According to the legend (and Dumas’ tale), the prisoner was forced to wear an iron mask over his face to hide his identity, and two musketeers stood ready to kill him if he ever it took off. Why he had been imprisoned was a state secret, and after his death his cell was scrubbed and scraped, its miserable furnishings destroyed in case he had written his name in a hidden place.

Twisted family secret

Another man who was intrigued by this legend was the French writer Voltaire, who looked into tales of the prisoner and the horrific mask he had apparently been made to wear. He found out that, far from being a story, the man in the iron mask had really existed – he was a prisoner who lived at the time of Louis XIV (reigned 1643–1715), who was known as the Sun King.

Voltaire speculated there was only one reason why an unknown prisoner would have to hide his face: he resembled the only man who would be instantly recognisable to all Frenchmen, the Sun King himself. Voltaire concluded the prisoner must have been King Louis’ secret twin, who had been imprisoned to preserve the security of the kingdom.

This twin theory inspired Alexandre Dumas, who incorporated it into the elaborate plot of Le Vicomte de Bragelonne. Largely as a result of Dumas’ tale and the films it later spawned, the legend of the man in the iron mask has intrigued people for many years.

However, the true story is starkly different from the tale that Dumas penned. After poring through letters sent between Louis XIV, the French minister for war Louvois, and a gaoler called Saint-Mars, I have come to the conclusion that the man in the iron mask was most likely a lowly prisoner named Eustache. While there is no smoking gun, the accumulation of evidence in this cache of letters points strongly to him.

What’s more, he didn’t permanently wear an iron mask. This was an invention of Voltaire, who wrote that the prisoner wore “a mask, the chin-piece of which had steel springs to enable [him] to eat while wearing it”. There is no historic basis for this, however. In reality, Eustache was only made to wear a mask – made of black velvet, not iron – in the later years of his life, and only when he might have been seen by onlookers.

The theory that the man in the iron mask was Eustache was first put forward by Jules Lair, a French lawyer-turned-historian, in 1890. It was rejected by many historians because Eustache was deemed not interesting or important enough – they thought, as Voltaire and Dumas did, that the man in the iron mask had to be someone of significance, so the search continued.

An ornate portrait of King Louis XIV of France by Hyacinthe Rigaud
Louis XIV of France, by Hyacinthe Rigaud in 1701. It was claimed that the man in the iron mask was the king's secret twin (Photo by Universal History Archive/Getty Images)

But there is no real reason why a lowly prisoner couldn’t have been the man in the iron mask. Before discussing the reason for Eustache’s imprisonment, we need to know his story.

It begins in late July 1669, when Louis XIV issued a lettre de cachet, an order for the arrest of a man named Eustache, who was to be captured on sight and taken to the fortress of Pignerol in the Italian Alps.

The terrible – and often bizarre – treatment he endured while imprisoned was remarkably similar to that in Dumas’ fictional retelling of the story: he was held under conditions of utmost secrecy and his gaoler, a former sergeant in the musketeers called Saint-Mars, ensured that he could not be seen nor heard by anyone.

Once a day, Saint-Mars dropped a meagre package of food on to the floor of his cell. And, if Eustache attempted to speak of anything but his most basic needs, Saint-Mars was to kill him, an order he declared he was ready to carry out: “If he spoke to me or anyone else of anything other than of his needs, I would run him through with my sword.”

A lowly valet

Here, Dumas’ version of events in Le Vicomte de Bragelonne veers away from the truth. Far from being the king’s secret twin, or even a prisoner of high rank, Eustache was instead described by Louvois as “only a valet”.

In 17th-century France, a person’s rank was preserved even in prison. As a valet, Eustache was of lowly status, and this was reflected in the paltry items provided for his use. He was given cheap clothes: as Louvois stated, garments for “these sorts of people” should last three or four years. By contrast, Saint-Mars’ other state prisoner, the aristocratic Nicolas Foucquet, the fallen superintendent of finance, was given new suits each season.

While Eustache had no one to take care of him or keep him company, Foucquet enjoyed the services of valets. Eustache’s food was barely sufficient to keep him alive, yet Foucquet ate the finest meals such as would have been available to him had he been free.

Yet there was one respect in which the two men were the same: Foucquet was also guarded securely and was forbidden from communicating with the outside world, at least for the first few years of his imprisonment.

The two men were thrown together while in prison, with Eustache being forced to serve as the disgraced superintendent’s valet. Being a prisoner’s valet was a decidedly undesirable job. Valets were required to lodge with their masters, remaining in prison and forbidden even to visit their families for as long as they were in service.

Foucquet was meant to have two valets while in prison. However one had died, so only one valet, named La Rivière, was at his master’s service. After failing to find a replacement, Saint-Mars remembered that Eustache had been described to him as a valet, and – with Louis XIV and Louvois’ permission – successfully placed him as Foucquet’s second valet.

He was initially expected to work for him only when La Rivière was unable to carry out his duties. Eventually, he became a permanent fixture, even being allowed to accompany Foucquet when the latter received permission to walk on the walls of the citadel. In time, Foucquet was permitted to entertain visitors in prison, and Eustache looked after their needs as he did his master’s.

A case of mistaken identity

Josephine Wilkinson explains why three other candidates who were put forward couldn’t have been the man in the iron mask

For many years, some scholars thought the man in the iron mask was an Italian diplomat named Matthioli. He negotiated the acquisition of the citadel of Casale for King Louis XIV, but was taken captive after he betrayed Louis. His candidacy was credible until it was discovered that he remained at Pignerol when Saint-Mars moved to Exilles.

A second candidate was a valet known as Martin, the servant of a man named Roux de Marsilly, who was allegedly involved in a Protestant plot to assassinate Louis XIV. Martin resigned from his post and settled in England.

Lured back to France to act as a witness against his former master, he was apparently captured and spent the rest of his life in prison. However, this is not borne out in the historical record.

Eustache Dauger de Cavoye (a man with a remarkably similar name to my candidate, who lived at about the same time) proved to be a plausible contender: the name matches, and his crime-ridden life offers sufficient reason for why he might have been arrested.

But Cavoye had been held in the asylum of Saint-Lazare while Eustache was at Pignerol, and it was there that he died in the 1680s.

With so many people coming and going, security became a concern, but Louis XIV and Louvois were not unduly worried. Saint-Mars was simply ordered to arrange with Foucquet “as you judge appropriate, regarding the security of the person named Eustache... recommending you above all, to see to it that he speaks to no one in private”. Foucquet, himself a state prisoner, now had the responsibility of guarding Eustache – and making sure that the reason for his imprisonment remained unknown.

What, then, was Eustache’s secret? Clearly, it had to do with his activities prior to his arrest. Evidence for this is found in a letter written by Louvois to Foucquet on the king’s orders. Louvois asked the former superintendent if Eustache had spoken in front of his other valet about what he had seen prior to his arrest. He then crossed out this line and replaced it with one which spoke about how Eustache had been employed before his arrest.

In the original lettre de cachet, Louis had merely stated that he was “dissatisfied” with this man’s behaviour. He made no further elaboration. Louis, therefore, offers no hint of why Eustache had so displeased him. However, the context in which Eustache was arrested could provide the answer.

Servants and spies

In the summer of 1669, important and secret negotiations were going on between King Charles II of England and Louis XIV. These were being conducted through Charles’ sister Henrietta, duchesse d’Orléans, who was married to Louis’ brother, Philippe. Charles and Henrietta used valets to carry messages back and forth across the English Channel, but these valets frequently engaged other servants to carry messages on their behalf.

Often, Charles and Henrietta did not know who these people were. Indeed, in a letter to his sister, Charles noted that he had received a letter from her through “the Italian whose name and capasity you do not know, and he delivered your letter to me in a passage where it was so darke as I do not know his face againe if I see him”.

Eustache, of course, was not this man, since he was not Italian, but French; however, this comment illustrates the atmosphere of secrecy that surrounded communication during this sensitive period. Shortly before Eustache’s arrest, Louvois and Le Tellier, his father and predecessor at the ministry for war, were included in these negotiations.

It is possible that Eustache had been employed by one or both of these men, or perhaps even by Henrietta herself, and that he had become privy to secret and sensitive information. This would account for Louvois’ anger towards Eustache, with the minister referring to him as a “wretch”. And the fact that Eustache was arrested near Dunkirk, one of the principal ports to England, adds more weight to this theory.

An 18th-century portrait of Henrietta of England holding a portrait of her husband, Philippe, brother to King Louis XIV of France
Henrietta, sister of King Charles II of England, holds a portrait of her husband, King Louis XIV's brother. The duchesse d’Orléans' involvement in secret negotiations may have been why Eustache was imprisoned for life (Photo by Fine Art Images/Heritage Images/Getty Images)

Whatever Eustache had heard, it was certainly deemed serious enough at the time to warrant a lifetime in prison. Upon the death of his fellow prisoner Foucquet, he was returned to his former cell.

Because it was believed that Foucquet's other valet La Rivière had learned Eustache’s secret, and because he had failed to report a security breach that had been discovered shortly before Foucquet died, he was not dismissed from his post and sent away as he should have been but was instead imprisoned with Eustache. They were held together in Eustache’s old cell until they could be transferred to another fortress, Exilles. La Rivière died there seven years later, leaving Eustache alone.

When they were imprisoned together, Eustache and La Rivière lost their names and their identities. Saint-Mars called them “the gentlemen of the Lower Tower”, or his two merles, or blackbirds. Later, Eustache would be referred to in official correspondence simply as Saint-Mars’ “old prisoner” or, as Saint-Mars himself liked to call him, “my prisoner”.

When Louvois died in 1691 and was replaced in the war ministry by his son, Barbezieux, the new secretary did not know who Eustache was or why he had been imprisoned. Eustache had been forgotten, and his secret had lost its importance.

The man in the velvet mask

Nevertheless, he still had his uses. Saint-Mars, who had enjoyed the prestige of being the keeper of illustrious prisoners such as Foucquet, now had no one in his care except Eustache, a man of low social status. In an attempt to preserve his own status as a gaoler, Saint-Mars exaggerated Eustache’s importance by letting people believe that he was guarding a secret prisoner.

Whispers abounded that he might have been Henry Cromwell, the son of Oliver Cromwell, or else the popular duc de Beaufort, who had disappeared at the siege of Candia.

Upon his transfer to the island of Sainte-Marguerite near Cannes, Saint-Mars took Eustache with him, providing him with an elaborate mode of transport: a chair tightly wrapped round with cloth. This was supposed to hide Eustache from onlookers, but instead merely attracted the attention of the curious.

According to one source, Saint-Mars also made Eustache wear a mask for the journey. However, he had not been made to hide his face when he travelled to Pignerol, nor when he was in his cell or serving Foucquet. Saint-Mars had not received any orders to hide Eustache’s face; it was merely another means for the gaoler to fuel the mystery surrounding Eustache, and thereby enhance his own prestige.

Finally, Saint-Mars became governor of the Bastille. While Eustache was initially to be left behind on the island, Saint-Mars insisted on bringing him to Paris. At this point, official communication about Eustache ends, although he is mentioned in the registers of a Bastille administrator, who noted that the prisoner arrived masked.

At the prison, he wore a black velvet mask which covered the upper portion of his face whenever he might expect to be seen, such as when he went to mass. Five years after arriving at the Bastille, in 1703, Eustache died while still a prisoner there and was buried in the prison’s parish churchyard of Saint-Paul’s.

In many ways, the man in the iron mask was the invention of Saint-Mars, an ambitious gaoler unable to let go of the celebrity status that guarding illustrious prisoners had bestowed upon him. In reality, Eustache was not the royal prisoner of legend – Saint-Mars had needed to cover his prisoner’s face not to hide who he was, but to hide who he was not.

Voltaire was more right than he realised when, referring to Eustache’s imprisonment, he said “no man of any consequence in Europe disappeared”.

Dr Josephine Wilkinson is a historian and author of The Man in the Iron Mask: The Truth About Europe’s Most Famous Prisoner (Amberley Publishing, 2021)


This content first appeared in the September 2021 issue of BBC History Magazine


Dr Josephine Wilkinson is a historian with a particular interest in 17th-century France, Her books include Louis XIV: The Real King of Versailles (Amberley, 2019) and The Man in the Iron Mask: The Truth about Europe's Most Famous Prisoner (Amberley, 2021)