Shortly after this, news came that the Megarians had become hostile, and that an army, under the command of Plistoanax, king of the Lacedaemonians, was menacing the frontier of Attica.

The Corinthians, enraged at this, complained in the congress of Sparta of the conduct of the Athenians, as did also the Megarians, who said that they were excluded from every market and every harbor which was in Athenian hands, contrary to the ancient rights and common privileges of the Hellenic race.

Archidamus, indeed, the king of the Lacedaemonians, sent ambassadors to Athens, was willing to submit all disputed points to arbitration, and endeavored to moderate the excitement of his allies, so that war probably would not have broken out if the Athenians could have been persuaded to rescind their decree of exclusion against the Megarians, and to come to terms with them.

And, for this reason, Pericles, who was particularly opposed to this, and urged the people not to give way to the Megarians, alone bore the blame of having begun the war.

Pericles passed a decree for a herald to be sent to the Megarians, and then to go on to the Lacedaemonians to complain of their conduct.

Accordingly Athens and most of the rest of Greece then at once made terms with him: but the Megarians in spite of this resisted and were captured only at a considerably later date, partly by force and partly by treachery.

Outside the isthmus, the Beeotians, Phocidians, Locrians, Megarians, and AEtolians formed a coalition under the leadership of the Athenians; and, as their ancestors had done scarcely two hundred years before against Xerxes and the Persians, they advanced in all haste to the pass of Thermopylae, to stop there the new barbarians.