Most people associate Marie-Antoinette with the diamond necklace affair, “Let them eat cake!” And the start of the French Revolution. The Queen of France and her royal husband, Louis XVI, were guillotined in 1793, 10 months apart. But her colorful life also included a possible clandestine love affair with a Swedish earl, and historians have worked diligently to decipher the surviving letters between the two for years.

The letters were encrypted, as was the custom at the time for politically sensitive correspondence. Fifteen of the surviving letters in the collection of the French National Archives also have significant parts redacted, amounting to some 108 unreadable lines in total. Using advanced x-ray imaging techniques and data processing methods, the redacted parts of eight of those letters have finally been revealed, according to a new article published in the journal Science Advances. The research is a collaboration between the National Archives, the French Museum of Natural History and the Fondation de France.

Marie-Antoinette and Count Hans Axel von Fersen of Sweden met as a teenager at a masked ball, when she was still Dauphine of France, and he became a frequent visitor to Versailles afterwards. Her royal husband was found to be unable to consummate the marriage for the first seven years.

Some have speculated that Louis XVI had a health problem that made him difficult to execute, but the queen’s brother, Holy Roman Emperor Joseph II, concluded during a visit that this was mainly due to the inexperience of the king and the lack of interest of the queen. He described the couple as “complete blunderers,” and as far as the young king is concerned, let’s just say that the Emperor’s letters to the house included very candid references to what is currently making the rounds on social media like the Mormon practice of “soaking”.

Finally, the couple got it right and Marie-Antoinette had four children, only one of whom lived to adulthood. But by then, rumors were already circulating about his alleged infidelity, and von Fersen was one of his alleged lovers. (Other candidates included the Duke of Orleans and the Comte d’Artois.) They were certainly quite close. In 1780 von Fersen requested a transfer to America as General Rochambeau’s aide-de-camp and fought valiantly at the siege of Yorktown. Eventually he returned to France as Swedish Ambassador to Versailles and became a member of the Queen’s inner circle.

When the French Revolution broke out, the royal family was placed under house arrest at the Tuileries Palace in 1791. The ever-loyal von Fersen helped design the botched escape plan that allowed the royal family to be recaptured from Varennes before reaching a safe haven. It was at this time that the queen and the count exchanged the letters preserved today in the National Archives of France.

Von Fersen was in Brussels when he learned that Marie-Antoinette had been executed, declaring himself “devastated” and “tortured” by the thought that she might have doubted his attachment to her. He survived the Revolution but also suffered a violent death: he was beaten to death by a Swedish mob who believed he was among those responsible for the disappearance of the Swedish crown prince. (He was not).

The ability to finally read the redacted portions of these letters could help researchers decipher other censored or disfigured historical documents. Studying fragile ancient artifacts with cutting-edge non-invasive imaging technology has become a powerful tool in unlocking the secrets of the past. As previously reported, in 2016, an international team of scientists developed a method to ‘virtually unwind’ the severely damaged En Gedi scroll found on the western shore of the Dead Sea, revealing the opening verses of the book of Leviticus. .

In 2019, a team of German scientists used a combination of advanced physical techniques to virtually “unfold” an ancient Egyptian papyrus, which is part of a large collection held at the Egyptian Museum in Berlin. Their analysis revealed that an apparently blank stain on the papyrus actually contained characters written in what had become “invisible ink” after centuries of exposure to light. In 2020, micro CT imaging enabled researchers to perform a virtual autopsy on the remains of a mummified Egyptian cat.

Earlier this year, we reported that scientists had used multispectral imagery on four supposedly blank Dead Sea Scrolls and found the scrolls to contain hidden text, most likely a passage from the Book of Ezekiel. The researchers also used X-ray tomography to virtually “unlock” a sealed 17th-century letter with an intricate folding method known as “letterlocking,” a type of physical cryptography, to protect the contents from prying eyes.

Thus, when Fabien Pottier and several colleagues from the Center de recherche pour la conservation des collections (CRCC) of the Museum of Natural History took on the task of discovering the censored parts of the letters between Marie-Antoinette and von Fersen, they naturally turned to similar techniques. The challenge was to disentangle the ink used for the original text from the ink used to blacken it. So the first step of the project was to test various potential techniques that might be able to distinguish the physical or chemical properties of different inks, to see if one could get enough contrast to disentangle them.

Visible and near infrared hyperspectral imagery initially seemed promising. Unfortunately, the black drafting ink absorbed almost all of the light in the visible range, and in the NIR range, both inks were made largely transparent. They were too similar to draw conclusive results. Pottier and his collaborators obtained the best results with X-ray fluorescence spectroscopy (XRF) in microscanning mode, and their preliminary analysis revealed that all letters (and redactions) were written with metal-gall ink. The metallic component is mostly iron, but other metals can seep in as impurities during the preparation of the ink (copper and zinc, for example). These can provide some sort of signature to help researchers differentiate between different inks.

XRF imagery produced useful basic maps, but the team still had to use custom imaging processing and other strategies in specific cases to read the written text, including cases where drafted passages were written from two sides of the paper. So far, Pottier et al. were able to “decensify” eight of the 15 letters written.

As for the remaining seven redacted letters, “All the methodological tools presented failed to recover any of the censored writings,” the authors wrote. “In these cases, the two inks (the editorial and the underlying text) appear to have similar compositions, making it impossible to read the passages written by the data processing described in this article.”

But they were able to conclude that von Fersen himself probably censored the letters and that the Queen’s letters to von Fersen were in fact copies made by the Earl (a common practice at the time). “He decided to keep his letters instead of destroying them, but redacted some sections, indicating that he wanted to protect the honor of the queen (or perhaps also for his own interests),” the authors wrote. “These redactions are a way of identifying the passages he considered private.”

While researchers still transcribe all paragraphs when they are written, one of these letters, written by Fersen and dated October 10-12, 1791, contained the phrase “Goodbye my good friend, I will never stop worshiping you.” There are many examples of similar vocabulary in the letters (“beloved”, “tender friend”, “worship”, “foolishly”) which hint at passionate attachment, but the authors are careful not to utter any hypothesis beyond the obvious.

“Reading under censorship does not allow to know the truth about the nature of their feelings because the interpretation of the texts is always questionable”, they write. “But for the historian, this correspondence remains a precious testimony of a troubled time, and of how tragic political events influence the transformation of emotions and the exacerbation of visible feelings, especially in the personal writings here in these sections. of drafting. “

DOI: Science Advances, 2021. 10.1126 / sciadv.abg4266 (About DOIs).