Battles & Wars › Greece, Rome & Han › Greco-Persian Wars
Ancient ciphers (Spartan scytale, Caesar cipher)
hidden messages in Herodotus (c. 499–480 BC); Caesar cipher 50s BC· Invention or discovery· Technology, codes & intelligence
Mostly agreedGood evidence; some details, dates or numbers uncertain.
The first ways of hiding military messages: secret writing in Herodotus, the Spartan scytale staff, and Julius Caesar's letter-shift cipher.
See it on the Battles & Wars map →What happened
Herodotus tells of a message tattooed on a slave's shaved head and hidden by regrown hair, and of the exiled Spartan king Demaratus hiding a warning about Xerxes under the wax of a writing tablet. Hiding a message is called steganography; a cipher instead scrambles it. The Spartan scytale was a strip wound around a staff of set thickness and written on; unwound, the letters looked jumbled. Caesar replaced each letter with the one three places later in the alphabet.
Why it matters
These simple tricks began the contest between code makers and code breakers that runs through Enigma to modern encryption, because generals always need orders the enemy cannot read.
Think of it like
A Caesar cipher is like a lock with one fixed combination: once anyone learns the shift, every message opens.
How we know
Herodotus's Histories, Plutarch's life of Lysander, Aeneas Tacticus's 4th-century BC manual on surviving sieges, which covers secret messages, and Suetonius's description of Caesar's cipher.
Still debated
Some scholars argue the scytale was only a message stick for authenticating orders, not an encryption device; ancient sources describe it briefly.
Inside this (1)
Connections (4)
▸Ancient ciphers (Spartan scytale, Caesar cipher) smuggled to Sparta a warning about Xerxes I of PersiaDebated
The connection
Herodotus says Demaratus, an exiled Spartan king living at the Persian court, learned of Xerxes's invasion plan. He scraped the wax off a writing tablet, wrote the warning on the wood beneath, and covered it with fresh wax so it passed the guards as a blank tablet.
When and how
From Persia to Sparta, around 484–481 BC. Herodotus says Gorgo, wife of Leonidas, guessed that the wax must be scraped off.
How sure are we?
Only Herodotus tells the story, and he himself was unsure of Demaratus's motives; it may be partly embellished.
Debates and open questions
Whether the warning really happened, and whether it changed Greek preparations, is unknown; the Greeks had other signs that Xerxes was coming.
▸Ancient ciphers (Spartan scytale, Caesar cipher) carried Spartan scytale messages in the Peloponnesian WarDebated
The connection
Spartan authorities sent orders to commanders abroad on a scytale: a leather strip wound on a staff and written on, readable when wound on a matching staff. Plutarch says such a message recalled the admiral Lysander soon after the war ended.
When and how
Sparta, 5th century BC. Thucydides mentions a scytale recalling the regent Pausanias around 470 BC; Plutarch's Lysander story dates to about 404–403 BC.
How sure are we?
References in Thucydides, Xenophon and Plutarch show the scytale was a real Spartan tool for official messages.
Debates and open questions
Whether it hid content as a cipher or simply authenticated official orders is debated; the earliest sources never describe it as secret.
▸Ancient ciphers (Spartan scytale, Caesar cipher) protected Caesar's messages during the Gallic WarsMostly agreed
The connection
When Quintus Cicero's camp was besieged by the Nervii in 54 BC, Caesar sent him a letter in Greek letters, so the Gauls could not read it if captured, tied to a spear thrown into the camp. Suetonius adds that Caesar used a letter-shift cipher for confidential letters.
When and how
Northern Gaul (today's Belgium), winter of 54 BC: Caesar relieving Quintus Cicero, brother of the orator.
How sure are we?
Caesar's own 'Gallic War' (Book 5) tells the Greek-letter story; Suetonius, writing more than 150 years later, describes the shift cipher.
Debates and open questions
Whether the Greek letter was just Greek language or a true cipher is unclear, and there is no proof the shift cipher was used in Gaul.
▸Ancient ciphers (Spartan scytale, Caesar cipher) evolved over two millennia into the Enigma machineMostly agreed
The connection
Caesar shifted each letter by a fixed amount, a method the Arab scholar al-Kindi showed in the 800s could be cracked by counting letter frequencies. Renaissance ciphers fought back by changing the substitution letter by letter. Enigma automated that idea: its rotors stepped with every key press, giving a new scrambled alphabet for each letter.
When and how
Rome, 50s BC; Baghdad, about 850 (al-Kindi); Rome, 1467 (Leon Battista Alberti's cipher disk); Berlin, 1918 (Scherbius's patent).
How sure are we?
Suetonius describes Caesar's cipher; al-Kindi's and Alberti's treatises survive; Scherbius's patent shows the rotor method.
Debates and open questions
Whether the Spartan scytale was really a cipher device or just a message staff is debated, so the oldest link in the chain is uncertain.