Battles & Wars › Ancient world › Ancient ciphers (Spartan scytale, Caesar cipher)
Signal fires and beacon towers
Lachish letters c. 588 BC; Han Great Wall beacons· Invention or discovery· Technology, codes & intelligence
Mostly agreedGood evidence; some details, dates or numbers uncertain.
Chains of fires or smoke on hilltops and towers that passed warnings quickly across long distances, long before the telegraph.
See it on the Battles & Wars map →What happened
A fire at night or smoke by day can be seen many kilometers away, so a line of posts could relay a simple prearranged message, usually 'enemy coming', faster than any rider. An inked potsherd from Lachish, about 588 BC, says Judah's soldiers were watching for Lachish's signals because Azekah's could no longer be seen. China's Han dynasty lined the Great Wall with beacon towers, using codes for the size of a raid. England's beacons warned of the Armada in 1588.
Why it matters
For thousands of years they were the fastest long-distance communication, letting commanders and governments react to raids and invasions within hours instead of days.
How we know
The Lachish letters (found 1935), Han wooden slips from Juyan and Dunhuang listing beacon rules, surviving tower ruins along the Great Wall, and English records of the 1588 beacons.
Still debated
Beacons carried only a few prearranged messages; how often they raised false alarms, or came too late to matter, is rarely recorded.
Connections (3)
▸Signal fires and beacon towers were mechanized as the Optical telegraph (Chappe semaphore)Mostly agreed
The connection
Beacon chains could send only a few prearranged signals, such as 'enemy coming'. Chappe's towers kept the idea of relaying sight-signals from hilltop to hilltop but added movable arms and a code book, so the line could carry any message, word by word, though still only in daylight.
When and how
From the Lachish beacons, about 588 BC, and Han dynasty Great Wall towers, to Chappe's Paris–Lille line in 1794.
How sure are we?
The continuity of method is clear; ancient writers such as Polybius also described torch codes that could spell out letters.
Debates and open questions
Whether Chappe drew on ancient accounts of signaling or reinvented the relay idea on his own is unknown.
▸Signal fires and beacon towers carried the alarm across England before the Defeat of the Spanish ArmadaWell documented
The connection
England kept a chain of hilltop beacons, tar barrels or wood piles on posts, guarded by local men. When the Armada was sighted off Cornwall in late July 1588, the beacons spread the alarm along the coast and inland, calling out county militias.
When and how
Southern England, July 1588; the beacons were organized by the Privy Council and county lords lieutenant.
How we know
Elizabethan government papers and county records order the beacons manned, and contemporary accounts describe them lit when the fleet appeared.
Debates and open questions
How fast and how widely the beacons actually spread the news is uncertain; Macaulay's famous poem of fires blazing across England is romanticized.
▸Signal fires and beacon towers linked Judah's hill forts during the Babylonian siege of JerusalemMostly agreed
The connection
As Babylon's army took Judah's forts one by one, an officer wrote to his commander at Lachish that his men were watching for Lachish's fire signals, since Azekah's could no longer be seen. Signals linked the forts guarding the approaches to Jerusalem.
When and how
Lachish and Azekah, southwest of Jerusalem, about 588 BC; the letter, ink on a potsherd, was found at Lachish's gate in 1935.
How sure are we?
Lachish Letter 4 survives, and Jeremiah 34:7 says Lachish and Azekah were the last fortified cities holding out besides Jerusalem.
Debates and open questions
The usual reading is that Azekah had fallen, but that is not certain, and the Hebrew word may mean signals in general rather than fires.