Secret Agents in Ancient Greece and Rome

Unsurprisingly, the role of a secret agent is very old. Even in ancient warfare, the power of information and deception was recognized and appreciated. Many wars were won and many cities conquered not by the arms of warriors, but by a successfully executed cunning plans and schemes. Some of the best practices of ancient secret agents and the occasions when such tricks were successfully pulled off can be found in the surviving written sources. Apart from the general historians who described the wars in full and mentioned some secret missions only as a part of the whole story, there were authors who focused on creating “how-to” texts to teach the principles of successful military strategy and tactics. Some of them dedicated whole chapters of their works to explore the subject. Most notable of those are Aeneas Tacticus, a Greek living in the 4th century BCE, and Sextus Julius Frontinus, a Roman living in the 1st century CE. Let us explore the documented and suggested practices in their works:

Coding Messages

  • In a standard letter or book, some letters can be marked by tiny dots, too small to notice for someone who is not looking for them. The recipient transcribes the marked letters and is able to read the secret message.
  • Dots can also be used instead of vowels in a text to make it apparently illegible. The number of dots in place of each vowel indicates the order of that vowel in the alphabet (one dot for “A”, two dots for “E”, three for “I” etc.)
  • Drill holes into a die or a piece of wood, one hole for each letter in the alphabet. Remember where you start and which hole represents your letter “alpha” (or“A”). Each of the other holes represents a different letter and the sequence of those letters is the same as in the alphabet. If the senders want to send a message, they will pass a thread through the holes – letter by letter. When the recipient receives the die, he needs to unwind the thread noticing the holes that are used and write down the corresponding letters. He will, of course, write down the letters in the order from last to first, but still be capable of reading the message in the end.

Hiding Messages

  • The message can be engraved on a small plate of metal, hidden between the sole and the lining of a shoe and sewn up. Even the messenger himself doesn’t have to be aware of the message. It is completely sufficient if the sender and the recipient have the opportunity to manipulate with is shoes.
  • Small metal plates with a hidden message can also be rolled and used as women’s earrings.
  • Messages also can be sewn into a dog’s collar.
  • An especially creative way to hide a message is to put it into the ass of a donkey (no kidding, Frontinus really describes this). Of course, the message may be hidden there only for a couple of moments when the messenger meets the enemy guards.
  • A small papyrus with a secret message can be hidden in the shoulder part of a tunic, while other clothing is put over it.
  • A message is sometimes rolled around and arrow that is shot to the enemy camp or city (on the previously agreed time and place)
  • A message can be written on a bladder that is then hidden in an oil-flask.
  • The sheat of a sword (on the inside) is a great place for hidden messages.
  • A message is sometimes engraved on a wooden writing tablet, but hidden under a layer of wax, that contains a completely different text.
  • A message can be written on a boxwood tablet using a fine ink and then whitened. The recipient puts the tablet into water and the text appears clearly.
  • If a messenger is wounded, the message can be written on leaves covering that wound as a bandage.
  • A really advanced method of concealing a message requires a slave. The sender shaves the head of this slave and has the massage tattooed on that head. Some time must pass until the slave’s hair grows back and he is ready to be sent out. The recipient received the slave, shaves his head and reads the message.

Dealing with the Messages of an Enemy

  • A message from an enemy was once discovered by a commander in the besieged city. The letters were headed to some of the noble citizens asking them to betray their city and hand it over to the conquerors. The commander did not go public with his discovery at first, but let the letters be delivered to their recipients and waited until those recipients wrote a reply. He knew, that at this point, the nobles could claim that they were innocent and didn’t hold the responsibility for the letters they receive. Instead, he interrupted the delivery of those replies, where the nobles clearly stated their willingness to participate and convicted their senders of treason.
  • During the Eastern campaign of Marc Antony, one of his generals (Ventidius Bassus) discovered an enemy spy in his ranks. The general didn’t give any clue that he was aware of the spy’s true intentions but fed him misinformation about his plans. The messages from the spy than convinced the enemy to proceed in a way that actually suited the Romans very much.

Sending an Agent to the Enemy

  • When sending an envoy to the enemy camp, Romans sometimes had him accompanied by officers who were dressed as slaves. The officers were capable of noticing important details in the camp and gather useful information. However, once this practice almost backfired at the end of the 2nd Punic war when one of the Roman officers was recognized. The Roman commander, Gaius Laelilius, didn’t hesitate and beat him on the spot like real slaves were beaten, to keep his true identity secret.
  • There are some stories where a single man is able to infiltrate the enemy, convince them of his hatred for his original homeland, gain a leading position among them and betray them by giving up the city to his (original) countrymen. Herodotus tells a story like this about the Persian conquest of Babylon, but also the story of Rome’s conquest of Gabii is based on the same principle. The role of the agent was given to Sextus Tarquinius, the son of the last Roman king Lucius Tarquinius Superbus (the historicity of his story is, however, highly doubtful).
  • Historians mention several accounts when enemy soldiers were able to enter a besieged city disguised, often as merchants or citizens that had been previously captured or killed outside the city walls.
  • One bold general (Epaminondas of Thebes) managed to benefit from a situation when he noticed that the women of the city, he besieged, went outside the walls for religious reasons. He had some of his men dressed in women’s clothes and mixed with those women, so they were able to accompany them on their way back to the city. Once there, these men opened the gates for him.
  • Sometimes it is not necessary to get your spy to the enemy city or army, but it is sufficient to pay off one of their men. The Romans successfully attacked the city of Syracuse on a day of festivities about which they had been informed by a bribed defender. Even Philip II. of Macedon (father of Alexander the Great) entered an enemy city after he bribed one of the defenders to park a cark just in the middle of an open gate. The attacking army then entered the city through that gate.


  • Aeneas Tacticus – How to Survive Under Siege
  • Sextus Julius Frontinus – Stratagems
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