The first recorded history of high-speed optical data transmissions began with the fall of Troy to the Greek army, around 1184 B.C.
When Troy was taken, a prearranged signal was relayed overnight from Troy to Mycanae, the kingdom of Agamemnon (he has promised to his wife Clytaemnestra to send news when the war was over), via a line of fire beacons, a distance of 600km (375 miles), much of it over the sea.
The event is chronicled by Aeschylus (525-456 B.C.) in his tragedy Agamemnon, with Clytemnestra receiving news of the signal from her watchman. The chorus, totally surprised, asks: “What Messenger is there that could arrive with such speed as this?”
“Hephaistos (the god of fire), sending forth from Ida a bright radiation. And beacon ever sent beacon hither by means of a courier fire.
Ida (sent it) to the rock of Hermes in Lemnos; and paying more than was due, so as to skim the back of the sea……..transmitting, like a sun, its golden radiance to the look out of Makistos.
And he, not dallying nor heedlessly overcome by sleep, did not neglect its share in the messenger’s duty, and afar, over the streams of Euripus, the beacon’s light gave the watchers of Messapion the sign of its arrival.
They kindled an answering flare and sent the tidings onward, by setting fire to a stack of aged heath. And the vigorous torch, not yet growing dim, leaped, like the shining moon, over the plain of Asopus to the rock of Kithairon and there waked a new relay of the sender fire.
And the far-sent light….shot down over the Gorgon-eyed lake and reaching the mountain of the roaming goats……
And they with stintless might kindled and sent on a great beard of flame, and it passed beyond the promontory that looks down on the Saronic straits, blazing onward, and shot down when it reached the Arachnaean peak, the watch-post that is neighbour to our city;
And then it shot down here to the house of the Atridae, this light, the genuine offspring of its ancestor, the fire from Mount Ida……transmitted to me by my husband from Troy.”
Also, in Egypt they have been remnants of towers that may have been part of a network of communications towers running along the north African coast by which signals of bonfires where used to communicate messages of state. They may have been used also as lighthouses, a navigation beacon for sailing ships out there in the Mediterranean sea.
Source: Aeschylus, Agamemnon, lines 280-316 trans. Eduard Frankel, Oxford: Clarendon Press, 1950), pages 109-111