Cryptography, code writing, has been employed by people to keep their message hidden from prying eyes for centuries. Apparently, “[i]t is not uncommon for authors on intelligence subjects to deny in the preface to their books any connection to intelligence services”. Therefore, the author of this article would like to start off this article by stressing that she has no ties to the intelligence community. With that said, we will now enter the medieval world of cloaks and daggers. Exciting? You bet! Although intelligence is nowadays mostly gathered via various types of technological gadgets, which obviously were not available during the medieval period, many aspects of the spy game were the same:
[T]he collection of intelligence by human means.It was done then, it is done now. A spy is a spy is a spy, and eavesdropping is eavesdropping whether done by a human ear or an electronic device. Ancient governments, like modern ones, realized that to keep their borders safe, to control their populations and to keep abreast of political developments abroad, they needed a means to collect the intelligence which enabled them to make informed decisions. Intelligence activities have always been an integral part of statecraft. And we are made painfully aware daily of the damage spies can do.
The history of espionage is almost as old as time. In fact, it is “the world’s second oldest profession”; the first being prostitution (but surely you already knew this). Sheldon notes that “Near Eastern bureaucracies had entire departments in the palace dedicated to these activities by the second millennium BC […]. Readers may be surprised to discover how much intelligence activity went on in the ancient world”. However, it should also be noted that “[w]hat constitutes intelligence activities is, of course, debatable even today. Is covert action a legitimate intelligence activity or should it be classified as a strictly military activity?” It is clear that studying espionage in another historical period is not very clear-cut and often crosses various disciplinary boundaries, as it may involve military history, diplomatic history (diplomats were often also acting as spies, particularly in the early modern period), intelligence history, as well as fields such as linguistics (when it comes to cracking ciphers and decoding coded messages) and runology. “Runes?” you ask. Yes, indeed! Runes were also occasionally used as a code in the (early) modern period. Runes had fallen out of use in the early middle ages, so very few people still remembered their meaning several centuries onward. Other obsolete or obscure languages were also used for encryption:
Ogham is form of Celtic writing that occasionally used cryptographic forms. Ogham survives chiefly in inscriptions on tombstones. Its alphabet consists of five groups of five letters, represented by one to five lines extending away from a horizontal line. In the first group, the lines extend above the horizontal line; in the second group, below it; in the third, perpendicularly above and below; in the fourth, diagonally above and below; the fifth group is heterogeneous. Methods for enciphering them are catalogued in the Book of Ballymote, a fifteenth century compilation of historical and genealogical information. […] One of the most charming things about ogham is the name it uses for its systems. One is called “the ogham that bewildered Bres” that comes from a story about a message written in this script that was given to the ancient hero Bres who was going into battle. He was so confused by the message, that he lost the battle while trying to figure it out.
As you can see, the possible areas we can investigate is (almost) endless. So in this article, the focus will be on medieval cryptography, trying to find out how ciphers came into being and how they evolved during the medieval period. Sheldon provides a brief overview:
With the collapse of the western empire, literacy all but disappeared. The monks of Europe kept alive the Latin alphabet and amused themselves by signing their manuscripts or adding the occasional gloss in cipher […]. The systems they used were simple. Phrases were written vertically or backwards; dots were substituted for vowels; foreign alphabets like Greek, Hebrew or Armenian were used with each letter of the plaintext replaced by the one that followed it. In the most advanced system, special signs substituted for letters. According to David, “for almost a thousand years, from before 500 to 1400, the cryptography of Western civilization stagnated.” And he does not see much progress within the Middle Ages itself: an “advanced system is as likely to appear in the 600s as in the 1400s.” He does argue that the really simple systems do fade away by the end of the period. The brilliant monk Gerbert, who reigned as Pope Sylvester II from 999 to 1003 and whose learning became legendary, kept his notes in the syllabic system called Tironian notes.(Sheldon, 160-161)
Tironian notes were used as late as the tenth century, but by the twelfth century, this shorthand method had been more or less forgotten, as was classical Latin. Furthermore, “spies and informers were part of the fabric of Anglo-Norman society”. Prestwich wrote an essay on this topic, in which he “gives examples of background intelligence being gathered, the collection of strategic and tactical intelligence, intelligence used to achieve surprise attacks, and the systems run by William the Conqueror, Henry I and Henry II”. Of course, no story on medieval secrecy and mystery is complete without the ever-intriguing Knights Templars:
In the archives of the modern order of Templars is the 13th-century “Corsini manuscript” that contains among other things a chart of the transmission of power of the order listing all the grand masters, the rules of the order, and most interesting to us, the palaeographic tables of a secret writing system used to encode secret documents, including their financial transactions.
Remember reading those funny stories from The Canterbury Tales? The man who wrote them, Geoffrey Chaucer, was not just ‘a’ poet: “By far the most famous cryptographer of the Middle Ages was Geoffrey Chaucer. He was a customs official, an amateur astronomer, and literary genius”. Imagine having that as your Twitter bio! Anyway, moving on. Sheldon informs us that
[i]n this work, [Chaucer] describes the workings of an astronomical instrument, and it was meant as a companion piece to his Treatise on the Astrolabe. He includes six short passages in cipher. He uses a symbol alphabet in which “a” is represented by a sign resembling a capital V, and “b” by one looking like a script alphabet. The encipherments give simplified directions for using the equatorie. The cryptograms are in Chaucer’s own hand, making them among the most illustrious encipherments in history.
So basically Chaucer was the Ian Flemming (the man who gave us James Bond) of his day. Who knew?! This revelation does make me want to whip out and re-read my copy of the Canterbury Tales for any hidden (secret) messages…
In the excellent book The ciphers of the monks: a forgotten number-notation of the Middle Ages, David King describes the history of ciphers:
The notation appears in its first manifestation in early-13th-century England: any number up to 99 can be represented by a single cipher. This simple notation is somehow related to an ancient Greek shorthand-notation that was discovered on a stone tablet on the Acropolis a century ago. These ciphers were brought from Athens to England by the monk John of Basingstoke (d. 1252) and were used by Cistercian monks in England in the second half of that century. A second, more useful version is first attested in the late 13th century in what is today the border country between Belgium and France: now any number up to 9999 can be represented by a single cipher. This manifestation of the ciphers is due to Cistercian monks, who were amongst the first to prepare indexes and concordances of books and whose other activity in developing aids to scholarship is already well-known. The ciphers were used in the Middle Ages in monastic scriptoria – for marking the scales on an astronomical instrument, writing year-numbers in astronomical tables, and for incising volume on wine-barrels. […] [T]he ciphers – the third numerical notation of medieval Europe after the Roman and Hindu-Arabic numerals – [remained] for so long essentially forgotten.
One of the most famous cryptographers is Roger Bacon, so this article would not be complete without some information on this extraordinary fellow. Roger Bacon, the English monk, was the only writer in the Middle Ages to describe cryptography but never actually use it. In this Epistle, written around the middle of the 13th century, he stated: “A man is crazy who writes a secret in any other way than one which will conceal it from the vulgar.” He then lists seven deliberately vague methods of doing so. Among them are the use of consonants only, figurate expressions, letters from exotic alphabets, invented characters, shorthand, and “magic figures and spells.” Some believe Roger Bacon to be the author of the Voynich Manuscript, but this is neither proven not generally accepted, especially by those who think it is a 16th century and not a 13th century manuscript.
Speaking of the Voynich Manuscript: this manuscript is famous for its cypher, which has not yet been cracked. Every year (or so) someone claims to have cracked it, which is met with loud laughter from medievalists everywhere. If you are looking for a challenge – and world fame – try to figure out what it says.
Nachleben of medieval ciphers
Even though the use of ciphers fell out of use at the beginning of the early modern period, it can sometimes still be found – often in surprising places. For example, the Freemasons (oh yes, put on your tin foil hat, dear reader!). King informs us that
[t]he French vertical ciphers were adopted by the Chapitre Métropolitain at the Grand Orient de France, the leading masonic lodge in Paris, as is apparent from a one-page pamphlet dated 1780 . They were also adopted, probably around the same time, by the Chavaliers de la Rose-Croix, as shown by an undated pamphlet in the library of the Grand Orient in Paris which also appears in an 1806 discussion of the “croix phiosophique” […]. Although the masonic ciphers were not necessarily directly of monastic provenance it is interesting to note that there were considerable contacts between the Freemasons and clerics and monks in 18th-century France (See, for example, Blanchet et al. Les moines et les prêtres franc-maçons) .
This is what these ciphers looked like:
In more recent times, the New York Times reports on 7 April 1912 that the Suffragettes used a cipher in their communications (actually just some pretty hilarious code words) that was apparently inspired by “literature of the political conspiracies of the Middle Ages.” The text of the article is reprinted below for your reading pleasure:
 Ibid., p. 8
 Ibid., p. 10
 Ibid., p. 8
 Ibid., p. 9
 Ibid., p. 168
 Prestwich, John O., “Military Intelligence under the Norman and Angevin Kings,” in George Garnett and John Hudson (ed.) Law and Government in Medieval England and Normandy. Essays in honour of Sir James Holt. Cambridge: Cambridge University Press, 1994, pp. 1–30, cited in Sheldon, p. 168
 Probst-Biraben, J. H., “Les Templiers et leur alphabet secret,” Mercure de France, Paris, (August 1, 1939), pp. 513–532, cited in Sheldon, p. 168
 Chaucer, Geoffrey, The Equatorie of the Planetis, ed. Derek J. Price, Cambridge: Cambridge University Press, 1955, cited in Sheldon, p. 163
 King, David A. The ciphers of the monks: a forgotten number-notation of the Middle Ages. Boethius, Band 44. Stuttgart: Franz Steiner Verlag (2001) p. 13
 Naudon, Histoire de la Franc-Maçonnerie, p. 90, fig. 84 cited in King, David A. The ciphers of the monks: a forgotten number-notation of the Middle Ages. Boethius, Band 44. Stuttgart: Franz Steiner Verlag (2001) p. 243
 Chéreau, Croix philosophique, p. 22. There is no discussion of the alphabet in the text, which was dedicated to the Grand Orient in Portugal. Cited in King, David A. The ciphers of the monks: a forgotten number-notation of the Middle Ages. Boethius, Band 44. Stuttgart: Franz Steiner Verlag (2001) p. 243
 King, David A. The ciphers of the monks: a forgotten number-notation of the Middle Ages. Boethius, Band 44. Stuttgart: Franz Steiner Verlag (2001) p. 244