Towards the end of the winter, Oropus, which was occupied by an Athenian garrison, was betrayed to the Boeotians. Certain of the Eretrians and of the Oropians themselves, both having an eye to the revolt of Euboea, were concerned in the enterprise. For Oropos, facing Eretria, while held by the Athenians could not be other than a serious annoyance, both to Eretria and to the whole of Euboea.
Having now possession of1
Oropus the Eretrians came to Rhodes, and invited the Peloponnesians to Euboea. They were however more disposed to relieve the distress of Chios, and thither they sailed from Rhodes with their whole fleet.
Near Triopium they described the Athenian ships in the open sea sailing from Chalcè: neither fleet attacked the other, but both arrived safely, the one at Samos, and the other at Miletus. The Lacedaemonians now saw that they could no longer relieve Chios without a battle at sea. So the winter ended, and with it the twentieth year in the Peloponnesian War of which Thucydides wrote the history.