In historical times it belonged to the Ozolian Locrians; but about 455 B.C., in spite of a partial resettlement with Locrians of Opus, it fell to the Athenians, who peopled it with Messenian refugees and made it their chief naval station in western Greece during the Peloponnesian war.
The change in Athenian foreign policy, which was consequent upon the ostracism of Cimon in 461, led to what is sometimes called the First Peloponnesian War, in which the brunt of the fighting fell upon Corinth and Aegina.
In the first winter of the Peloponnesian War (431 B.C.) Athens expelled the Aeginetans, and established a cleruchy in their island.
There is some doubt as to whether this Acusilaus was of Peloponnesian or Boeotian Argos.
There has been considerable discussion as to the exact figures, the evidence in Thucydides being highly confusing, but it is most probable that the available fighting force was not more than half that of the Peloponnesian confederacy.
On the other hand, Tissaphernes undertook to pay the Peloponnesian sailors a daily wage of one Attic drachma (afterwards reduced to a drachma).
During the Persian invasion the Tegeans displayed a readiness unusual among Peloponnesian cities; in the battle of Plataea they were the first to enter the enemy's camp. A few years later they headed an Arcadian and Argive league against Sparta, but by the loss of two pitched battles (Tegea and Dipaea) were induced to resume their former loyalty (about 468-467).
During the Persian wars the state, which had recently joined the Peloponnesian League, could still muster 3000 hoplites.
In the Peloponnesian War the Boeotians, embittered by the early conflicts round Plataea, fought zealously against Athens.
Both the forms of the letters and the style of the architecture show that the colonnade cannot date, as Pausanias says, from the time of the Peloponnesian War; Th.