Developing the Art of Secret Writing across Borders: The Journey of Marie de Guise’s Ciphers between France and Scotland

This article looks at Marie de Guise’s part in the development of ciphered writing in Scotland. Based on six surviving enciphered dispatches between the Regent of Scotland and the French ambassadors between 1553 and 1560, it analyses Guise’s increasing reliance on secret writing in periods of war or domestic conflict as well as the encoding technique she or her secretaries used. This cryptoanalysis leads to a discussion of Guise’s political use of ciphers and her attempt to prevent French skills in the field to be shared with the Scots. Finally it discusses the information game, involving three players – France, Scotland and England – in which the Regent took part during the Reformation rebellion and which contributed to her fall. Guise’s ciphered letters as well as the matching code tables are also transcribed here to illustrate the contribution of continental consorts to this aspect of early modern diplomatic culture.