History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
When he was in that quarter before, after the return of the Hellenic fleet from Cyprus,[*](cf. Thuc. 1.94.2.) he had taken Byzantium, then in the possession of the Persians, and certain connections and kinsmen of the King were captured in the place when the city fell. These prisoners he sent back to the King without the knowledge of the allies in general, whom he gave to understand that they had escaped from him.
And he was carrying on this intrigue in concert with Gongylus the Eretrian, the very man whom he had placed in charge of Byzantium and the captives. And he also sent a letter by Gongylus to the King, in which the following was written, as was afterwards discovered:
"Pausanias, the Spartan commander, wishing to do you a favour, sends you back these men whom he took with the spear. And I make the proposal, if it seems good to you also, to marry your daughter and to make Sparta and the rest of Hellas subject to you. And I am able, I think, to accomplish these things with the help of your counsel. If any of these things pleases you, send a trusty man to the sea, and through him we shall in future confer." So much the letter disclosed.
Xerxes was pleased with the letter, and sent Artabazus son of Pharnaces to the sea, commanding him to take over the satrapy of Dascylium, superseding Megabates, who was governor before; and he charged him with a letter in reply to Pausanias, bidding him transmit it to him in Byzantium as quickly as possible and to show him the seal, and if Pausanias should give him any direction about the King's affairs, to execute it with all care and fidelity.
And he on his arrival did other things as he was told and transmitted the letter. And this reply of the King ran as follows: