Acquired by the Archives of the French Ministry for Foreign Affairs in 1992, this isolated, fully encrypted letter was written on 21 January 1547 by King Francis I and addressed to Christophe Richer, his ambassador to the King of Denmark. Sent during the Rough Wooing (1543–1551), which was part of the Anglo-Scottish wars, it conveys the concerns of the King of France (an ally of Scotland through the Auld Alliance) about the requests of the King of England for support from the King of Denmark. Richer was tasked with dissuading the King of Denmark from providing such support. The letter had previously undergone incomplete cryptanalysis whose date and author are unknown. In addition to completely deciphering the letter, this new cryptanalysis revealed numerous errors in the original encryption. The original cipher key was also identified within the collections of the Bibliothèque nationale de France. It is based on homophonic substitution with additional protocols, such as doubled characters, null characters and a nomenclator.