Secret Letter Detailing Late Medieval Britain Fully Decoded

A 15th-century diplomatic cipher has been fully decoded after more than 160 years of failed attempts, revealing sensitive intelligence regarding the political landscape of late medieval Britain. The breakthrough was achieved by three researchers from the University of Toronto, who produced the first complete translation of a secret letter written in 1498.

The document was authored by Pedro de Ayala, a nobleman from Toledo who served as a diplomat for the Spanish rulers Ferdinand II of Aragon and Isabella I of Castile. Written on July 25, 1498, while Ayala was in London, the eleven-page letter was intended for the Spanish court to provide a report on the courts of Henry VII of England and James IV of Scotland.

Cryptographic Analysis and Recovery

The letter was rediscovered in Spanish archives in 1860. For 166 years, historians and cryptographers attempted to unlock its contents, but the complexity of the encryption proved a significant barrier. To protect the intelligence from rivals, Ayala utilized a partial encryption method that combined symbols with the omission of specific words.

According to the findings published in the journal Renaissance Studies, scholars Adrian William Jaime, Valeria Tapia Cruz, and Mairi Cowan developed a cipher key that mapped specific symbols to letters and entire words. The researchers noted that Ayala employed a technique to frustrate decoders by using multiple different symbols to represent the same letter, a method that increases the difficulty of frequency analysis.

Intelligence on the British Isles

The decoded text provides a detailed account of the diplomatic and social conditions in Britain at the end of the 15th century. The letter includes reports on marriage negotiations between Spain and England involving Katherine of Aragon, as well as information regarding the voyages of John Cabot to North America.

Ayala’s reporting on Scotland is notably complimentary. He describes King James IV, who was 25 years old at the time, as religious, generous, and courageous. The diplomat further claims that the Scottish monarch was proficient in seven languages: Latin, French, German, Flemish, Italian, Spanish, and a language Ayala identifies as being spoken by savages have in a certain part of his kingdom, likely referring to Gaelic.

The letter also contains sociological observations about Scotland, which Ayala describes as a peaceful kingdom without any inconvenience and is very noble and very ancient, endowed with many virtues.

The women are very courteous in the extreme. I say this because they are very bold. They are honest in what is substantial. They are absolute governors of their houses and even of their husbands in what concerns the administration of wealth, likewise in collecting it as in spending it. They are a very graceful group of women and very beautiful.

Pedro de Ayala, 1498 diplomatic letter

In contrast to his praise for Scotland, Ayala’s descriptions of the English court are reported to be far less positive, despite the diplomat’s own positive relationship with King Henry VII.