Mary, Queen of Scots was beheaded on this day in 1587 after 19 years of imprisonment ordered by her cousin Queen Elizabeth I, and experts say a new discovery concerning her is the most significant we've had in at least a century: a secret correspondence that was thought to have been lost has been found and deciphered. The team who did so has wide-ranging skills, per the Guardian: George Lasry is a computer scientist and cryptographer; Norbert Biermann, a pianist and music professor; and Satoshi Tomokiyo, a physicist and patents expert. They used manual and computerized techniques to break the code contained in 57 letters written by her between 1578 and 1584—and at the outset of the project, they didn't know Mary was the author.
As a press release explains, the trio was browsing the French National Library's archives looking for enciphered documents. Some of the letters were catalogued as Italian texts, and as the men began chipping away at the code they soon realized the letters were composed in French and weren't about Italy. References to captivity and the name Walsingham (Elizabeth's spymaster) led them—"to our great surprise," per the study published Wednesday in Cryptologia—to determine they were some of Mary Stuart's lost letters. A search for similar letters in the archives turned up a total of 57.
A number of the letters were delivered to the French ambassador to England, Michel de Castelnau de Mauvissiere. In them, Mary wrote of her poor health and the conditions she was being held in, and described her efforts to convince Elizabeth to grant her release. The letters detail an effort to curry favor with some of Elizabeth’s officials using presents. The release notes that while it had been known that Mary Stuart and the ambassador had a confidential communication channel, the discovery shows it was in use as early as 1578. The find presents "a voluminous body of new primary material on Mary Stuart—about 50,000 words in total," per the study. (Mary reportedly ate well while imprisoned.)