History of the Peloponnesian War

Winter was now drawing towards its close, when the Boeotians took Oropus by treachery, though held by an Athenian garrison. Their accomplices in this were some of the Eretrians and of the Oropians themselves, who were plotting the revolt of Euboea, as the place was exactly opposite Eretria, and while in Athenian hands was necessarily a source of great annoyance to Eretria and the rest of Euboea.

Oropus being in their hands, the Eretrians now came to Rhodes to invite the Peloponnesians into Euboea. The latter, however, were rather bent on the relief of the distressed Chians, and accordingly put out to sea and sailed with all their ships from Rhodes.

Off Triopium they sighted the Athenian fleet out at sea sailing from Chalce, and neither attacking the other, arrived, the latter at Samos, the Peloponnesians at Miletus, seeing that it was no longer possible to relieve Chios without a battle. And this winter ended, and with it ended the twentieth year of this war of which Thucydides is the historian.