I was about to get back into the next big event in The Retreat to Avalon, namely King Arthur’s capture of Namnetis (Nantes, France), when I realized that all the preparation for his campaign involved something I haven’t gotten into yet: Ancient Espionage! You might be surprised by how much espionage is going on in my series, The Arthurian Age.
I’ve always loved a good spy story. I’ve also had the background to know that espionage comes in many forms and nearly everyone has some experience with it. It’s not just Sterling Archer or Mata Hari. The smallish kid who has to outsmart the bullies to get safely home from school practices it. Politicians routinely use it on each other and their constituents. Journalists, businessmen, police officers, even parents. Espionage is about intelligence gathering, misdirection, deception. There is no reason to believe our ancestors weren’t sophisticated enough to make use of it, despite the lack of technology that makes it easier today.
Espionage in the Ancient World
Some of the earliest references to spies come from the region of Syria and Iraq in the 18th century BC. The tablets describe well-developed approaches to military and civil espionage (great article here). The 15th century BC Egyptian Amarna Letters discuss deceitful diplomacy, uncovering disloyal citizens, covert operations and details of rival kingdoms. A century later, the Hittite king Muwatalli II sent spies posing as deserters to lead Ramesses II into an ambush at the Battle of Kadesh. Shortly after this, Moses sent twelve spies into Canaan to prepare for the Israelites to conquer the region. In the 5th century BC, Sun Tzu wrote The Art of War, with an entire chapter dedicated to espionage. The Arthashastra of the 1st century AD is an ancient Indian text about governance, including the use of espionage against citizens as well as foreigners.

Everyone knows of the Trojan Horse of The Iliad. It’s hard to know how much is true history, but that wasn’t the only covert operation of that war. Odysseus infiltrated Troy as a slave to gather intel on the Trojans and determine their morale. Later, Odysseus and Diomedes infiltrated behind Trojan lines at night and captured a Trojan who had been sent to spy on the Greeks. They interrogated him, then killed him, and used the information to attack the camp of the Thracians, allies of the Trojans, killing their king, Rhesus.
The later Greeks used the scytale, an early encryption device that involved wrapping a material around a cylinder of a specific size, then writing a message, letter by letter, across each strip. Unwound, the strip of cloth would look like a random string of letters. The person receiving the message would wrap the strip around a cylinder of the same circumference, enabling them to place the letters in the correct order again. Anyone capturing the strip must first recognize it for what it is, and then correctly determine the size of the cylinder in order to decode the message.

The Romans made a science out of everything, and espionage was no exception. Their earliest spies were scouts and messengers assigned to military units. These developed into the Speculatores, experts who typically worked alone or in pairs gathering intelligence or performing special operations. They took on the roles of bodyguards, interrogators, executioners, torturers, and assassins. They were bodyguards for the emperor and operated as a secret police until that role was take over by the Frumentarii or “Grain Collectors”.
The Frumentarii began as couriers, tax collectors, and were in charge of getting grain supplies to military units. When the emperors decided they needed some sort of intelligence service geared more towards internal security, the Frumentarii were chosen because of their movements throughout the empire and contacts with civilians and foreigners. They became a secret police force until eventually disbanded due to the abuse of their considerable power.
Espionage in the Arthurian Age
With the fall of the Roman Empire, western Europe became decentralized and structured espionage systems devolved. The two greatest sources of intelligence gathering were merchants and the clergy. The Church’s extensive network of priests, monks, nuns and community lay-members was a powerful source for the exchange of news and more confidential information. For the most part, this source would be focused on the aims of the Church, but could be shared when the Church’s goals coincided with a ruler’s goals, or unscrupulous members could find advantage.
Perhaps a greater source of espionage were the merchants and itinerant craftsmen. With the collapse of Roman trade networks in Britain, many crafted goods became rare and expensive. Merchants had to navigate pirate-infested waters, or travel roads beset by bandits. A tradesman, such as a blacksmith or skilled carpenter, might travel from place to place finding work, if unable or unwilling to find a permanent patron. In fact, the high status of craftsmen is portrayed in the ancient British poem, Culhwch and Olwen:
“The knife is in the meat, and the drink is in the horn, and there is revelry in Arthur’s hall, and none may enter therein but the son of a king of a privileged country, or a craftsman bringing his craft.”
The status afforded craftsmen and the wide ranging travels and networking of merchants made them privy to news, rumors and secret information. This fact was well known to the later Vikings, who often planned their raids based on information they received from merchants, or by working as merchants themselves. They would learn local customs, develop informants and learn who and where persons of power were located.

Aside from merchants and artisans, money, threats, promises or revenge could turn servants, slaves and even family members into informants for an adversary to use. A wily leader looking to mislead an adversary could use the ever present rumor mill amongst soldiers, or community gossip channels to spread disinformation, knowing that the enemy has his own spies. And you can be certain that women were far more influential than their mentions in history books would make it appear. There is a great article about the history of women in espionage at this link. I even wrote a short story called The Letter, about a girl who becomes a spy in one of the pivotal events related to The Retreat to Avalon. While the event is real, the specifics, including the main character, are my own speculative invention. If you would like to read the story, send me your email address, and I’ll be happy to send it to you for free.
Additional Sources
If you’ve already read The Retreat to Avalon, you may recognize some of the espionage techniques I’ve talked about here. A couple of good books that were part of my research, if you are interested, are The Enemy within: A History of Spies, Spymasters and Espionage by Terry Crowdy, and Spies, Espionage, and Covert Operations: From Ancient Greece to the Cold War by Michael Rank.
Thanks for coming by. As always I love to get comments and questions. And if you can spare a moment to leave a rating or short review for any books you’ve liked by any author, you can be assured each one is greatly appreciated and helps so much.

My favourite is the “The knife is in the meat…” We have used a variant in that “none may enter save a man of might, a man of craft or a poet”. Note the old usage of man being both genders.
In the English Civil War there was an interesting division between a spy and a scout. I believe that a junior British officer was executed as a spy although he might have been legitimately scouting, in your revolutionary war.
Baden-Powell was both a scout and a spy at different times. As a spy he investigated some fortresses using painting as a cover. For example he would paint a sort of fictitious butterfly with a diagram of the place concealed in the painting.
You are right that there must have been spying in the Early Middle Ages but any frontiers would have been really leaky and certainly information would be part of a merchant’s goods.
Forgive me an anecdote, my Father was a wireless intercept operator in WW2 initially in the Western Desert forward of the Eighth Army as a small unit. He never said but it seems the wireless intelligence they got fed into Enigma.
That is interesting about your father!
In later eras, the thing that usually differentiated a scout and a spy was whether or not a uniform was worn. For our Revolution, that might have been more difficult, as most militias didn’t have uniforms, but acted as regular soldiers.