History of the Peloponnesian War
Thucydides
Thucydides. The history of the Peloponnesian War, Volume 1-2. Dale, Henry, translator. London: Heinemann and Henry G. Bohn, 1851-1852.
Now Astyochus, the Lacedaemonian admiral, set sail, as he had intended, with four ships from Cenchrea, and arrived at Chios On the third day after his coming there, the Athenian ships, five and twenty in number, sailed to Lesbos under the command of Leon and Diomedon; for Leon had subsequently brought a reinforcement of ten ships from Athens.
The same day, at a late hour, Astyochus also put out, and taking one Chian vessel in addition to his own, sailed to Lesbos, to render it whatever assistance he could. Accordingly he came to Pyrrha, and thence the next day to Eresus, where he heard that Mitylene had been taken by the Athenians on the first assault.