Thasos signals changes in foreign policy alignments all over Greece.

The Thasians had appealed to Sparta for help, asking it to invade Attica, and the Spartans had secretly agreed to do so.

According to Thucydides, they would have done it had they not been detained by a massive revolt of the helots and “perioikoi,” who have taken advantage of a severe earthquake in 464-463, which has killed thousands of civilians, to occupy the strong position of Ithome in Messenia.

The great revolt, known as the Third Messenian War, threatens Spartan supremacy among the Greek states.

Archidamus II, king of Sparta from about 469, organizes the defense of Sparta and suppresses the Laconians, then turns to deal with …