Featured image: Fort Royal on Ste Margurite Island was home to The Man in the Iron Mask for 11 years| Photo by Kazimierz Mendlik, CC BY-SA 3.0, via Wikimedia Commons

The mystery continues: is this France’s greatest secret? 

by Carolyn Ray

I’m not expecting to learn about France’s greatest secret when I board the ferry in Cannes to Sainte-Marguerite Island on a sunny Friday morning. On this small island just off the coast, there’s a bird sanctuary, blue turquoise waters, fragrant pine and eucalyptus trees and children playing happily on the beach. It hardly seems like a place where an unidentified prisoner of state was held in complete isolation for 11 years.  But this is also the island that housed one of the most notorious legends in French history — the “Man in the Iron Mask” — at Fort Royal, the island’s main attraction.

The fort was constructed between 1624 and 1627 on the site of remains dating back to Roman antiquity. In 1685, when the royal fort housed a large garrison, it was converted into a state prison. We walk past groupings of terracotta-coloured buildings, with sea foam green shutters, that contrast against the bright blue sky. My guide, Christophe Roustan Delatour, takes me to a black iron gate marked ‘Danger’. He produces a metal key and invites me to follow him.  “It’s here,” he says, “that the Man in the Iron Mask stayed when he was originally brought to the island.”

This is a story I haven’t heard before, but I soon learn that during the reign of Louis XIV of France (1643–1715), this unknown man spent 34 years in the custody of the same jailer, Bénigne Dauvergne de Saint-Mars, in four successive French prisons, including Fort Royal.  According to the legend, he wore a metal mask to hide his identity, hence the name.

Navigating through a narrow path that winds around to the back of the building, we climb down a narrow flight of brick stairs into the dark basement, into a room with one small window. There’s a small shaft of sunlight illuminating part of the room. I feel a shiver down my back. It feels spooky. I wonder how many souls were kept here, in this prison cell underground?

The legend of the Man in the Iron Mask

The Man in the Iron Mask was born in 1658 and died in 1703 in the Bastille in Paris. For 34 years, strict measures were taken to keep his identity a secret. According to Delatour, there are more than 50 theories debating his name, the most prolific that he was the older, illegitimate brother of Louis XIV, or a twin.

Most of these theories, including one popularized by Alexandre Dumas, call the man ‘Eustache Dauger’. Surrounded by extraordinary precautions, he was kept on the borders of France, hidden in the Italian Piedmont and then on Sainte-Marguerite. Three centuries of investigation have revealed his name: Eustache Dauger. A famous unknown, he became one of the most famous prisoners in history.

But who was Eustache Dauger? What had he done to deserve such a punishment? Spy, traitor, or inconvenient witness… why wasn’t he simply eliminated?

Questioning the mainstream narrative

“In 2019, the City of Cannes organized an extensive exhibition (the first of its kind) dedicated to the Iron Mask and the enquiry into his identity by early and modern historians, fiction writers and the film industry,” Delatour says. “As curator of the exhibition, I worked on the subject for about two years and quickly realized that the predominant, mainstream theory was verifiably false.”

Delatour, who is an art historian and Deputy Director of the Cannes Museums, says that most French scholars and journalists held the view that the Iron Mask, although undoubtedly historical, was based on a misunderstanding: that the prisoner was an insignificant character, who probably witnessed or was privy to a State secret for which crime he had be arrested and jailed by order of King Louis XIV. Scholars thought that his malicious jailer, an ambitious and unscrupulous musketeer named Benigne Dauvergne de Saint-Mars, had invented a legend in order to attract attention and pass himself off as more important than he was — and it had worked. Saint-Mars became the top prison director in the realm and was promoted to governor of the famous Bastille, a highly lucrative post.

Delatour’s research showed the opposite. “Saint-Mars was a diligent servant of the king and his ministers,” he says. “I decided to start from scratch, review all of the available sources, discover new ones if I could and draw my own conclusions, using a strict historical method.”

According to Delatour, two writers were fundamental in finding out this identity and the true secret behind the Iron Mask: Maurice Duvivier, author of Le Masque de fer in 1933 and Marie-Madeleine Mast (1974). Delatour published his own novel, called “The Iron Mask – A State Secret Revealed,” in January 2023.

“I took my cue from their work, and several other authors of the 18th and 19th centuries,” he says. “I examined more than 300 primary source documents, witness accounts, locations and objects, and came to the same conclusion as M.-M. Mast — that Eustache Dauger de Cavoye was Louis XIV’s older half-brother, they were both sons of François de Cavoye, and that the deep, dark secret was the illegitimacy (bastardy) of the Louis XIV, who although a Habsburg by his mother, was not the legitimate “Dauphin” (heir apparent), was not even a Bourbon, and should never have been king of France.”

The Iron Mask (whoever he was and for whatever reason) was treated in the most unique way and was obviously highly important to the king. In fact, no other prisoner had been subjected to this kind of treatment. Fort Royal, the most secure prison in Europe, was built especially for him. He stayed there for 11 years, from 1687 to 1698, with only one window looking out to Cannes, but there is some evidence of comfort, with a fireplace and drawings on the wall still evident. While it’s said he initially wore a mask of iron, there’s also a theory that he wore a velvet mask, although neither of these exists as evidence.

Louis XIII’s legend to protect his throne

As for the secret itself, we have only to analyse the relationship of Louis XIII and his wife, Anne of Austria (a Habsburg princess from Spain), to realize that the story of Louis XIV’s conception was completely fabricated, Delacourt says.

“The two monarchs despised each other, and they only conspired to sire a (bastard) child, after 22 years of marriage, in order to protect themselves and the realm from civil war,” Delatour says. “Throughout Europe, this was widely known at the time and there are several written accounts hinting of declaring outright that Louis XIV was illegitimate. 19th century historians, such as Michelet, regarded this as fact. But in the 20th century, the Sun King’s history was whitewashed and the old doubts about his parentage forgotten or disregarded. His reign, of course, is regarded as the pinnacle of French classical civilisation, might and brilliance.”

Why, one might wonder, wasn’t the older half-brother executed?

Delatour says that as a devout Catholic, the King, could not murder his own half-brother, under pain of eternal damnation. This would have been a capital sin.

“Contrarily to the purpose-built prison of Saine-Marguerite, the Bastille was not the “best and most secure prison in Europe”. But it was only a two-hour carriage ride from Versailles. Perhaps, bringing the Iron Mask from the border of the kingdom (Cannes) to Paris was meant to facilitate an interview with the King? We can only speculate.”

Delacourt says that the prisoner “Eustache Dauger” (a very uncommon name) had a homonym living at the same time, Eustache Dauger de Cavoye.

“This Eustache not only knew most of the protagonists in the story but had been raised at the court of France with Louis XIV,” says Delacourt. “Eustache’s own blood brother, Louis de Cavoye, became a lifelong friend (one of the very few) of the king. Eustache de Cavoye disappears in 1668 a year before the Iron Man’s arrest (1669), is thrown in prison, and supposedly dies in captivity around 1680, the very same year that the Iron Mask loses his own identity in prison and becomes anonymous. In my opinion, these two Eustaches — the prisoner and the childhood acquaintance of the king– are one and the same. Too many “coincidences” convince me of this.”

In Delatour’s mind, the King was the all-powerful decision-maker in this story.

“The State secret of the Iron Mask required so much effort and expenses to keep, and was in fact a family secret,” he says. “Louis’s goal was to destroy any element that threatened his rule, and his long reign is a testament to authoritarianism, personal glorification, and absolute power. He, in fact, methodically put an end to the old order and ushered in the new. Going so far as to undo what his “ancestors” had achieved, such as the Edict of Nantes, which had established a lawful peace between Catholics and Protestants. And the Court of Versailles, which he created, ushered in the end of the provincial, centuries-old French aristocracy.”

Not a myth but reality

While the Man in the Iron Mask is one of the strangest events in French history, it’s not a legend or a myth, Delatour says. “It actually happened, and not by accident or a quirk of nature. Therefore, there must exist a rationality, a good reason behind this 34-year-old story. And so, we are entitled to know about it.”

When it comes to historical narratives, it also teaches us to question events of the past, to read and analyze sources, and piece together a narrative or theory from fragmented clues and leads.

“The Iron Mask’s story reflects how political power protects itself, if necessary, by any means possible,” Delatour says. “There’s a universal lesson here. ‘History is written by the winners,’ as the saying goes. This should matter to everyone, whatever time period or place we live in.”

To visit Fort Royal, take a ferry from the Vieux Port of Cannes. Learn more here.

How to get to Cannes

From within France, travel by train to Cannes. Check prices on Trainline here.

If arriving by air, the closest airport is in Nice. Check for flights here.

Where to stay: The gorgeous Five Seas by Inwood Hotels.

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