16th-century Spanish code cracked 

16th-century Spanish code cracked 

 A 500-year-old secret code used in letters between one of Spain’s most successful monarchs and his military commander has been cracked.

The letters of Ferdinand II of Aragon, the first king of what became modern-day Spain, have frustrated historians since the 16th century.

Constructed using more than 200 special characters, they have finally been deciphered by the staff at the Spanish National Intelligence Centre (CNI).

Ferdinand ruled during the Reconquista, when the Muslim Moors were finally driven from their last Spanish possessions of Granada in 1492 (pictured), and Christopher Columbus sailed to the Americas.

The letters from 1502 and 1506 between Ferdinand and Gonzalo de Córdoba reportedly include strategic orders during military campaigns in Italy in the early 16th century. They were written using secret code in case they were seized by the enemy.

At the foot of one letter de Córdoba, known as “the Great Captain”, had deciphered a few sentences, offering an insight into the code.

Four of the letters on display at the Spanish military museum in Toledo took intelligence operatives almost six months to decipher. Some of the letters were 20 pages long.

Described as a “Rosetta Stone” moment, it is hoped the breakthrough will lead to more of the coded letters being deciphered.

The deciphered letters detail instructions on troop deployments and reprimand a commander for not consulting the king before engaging in a diplomatic initiatives.

In the early 16th century, it would have taken around 15 days for the letters to reach southeastern Italy, where de Córdoba was stationed.

The “Great Captain code” was constructed using 88 symbols and 237 combined letters.

Encrypted letters were a common system in Italy at the time but agents who broke the code described the letters as “very well thought out”.

For each letter the code used between two and six figurative characters, such as triangles or numbers.

The symbols used were written without separating words and phrases.

At the start of the 16th century, Spain and France were fighting for control of the Mediterranean and between 1499 and 1504 the Kingdom of Naples was the key battleground.

Spain took control of Naples from France in 1504 and ruled the southern Italian region until 1647.

Ferdinand’s policy of so-called modernisation included a ban on anything other than Roman Catholicism. The establishment of the Spanish Inquisition (1478) to enforce religious uniformity and the expulsion of the Jews in 1492 were both part of a policy designed to strengthen the church, which would in turn support the crown.


Ferdinand II of Aragon in red depicted at Granada in 1492. Picture credit: Wikimedia

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