History of the Peloponnesian War

This then was the treaty and alliance that was concluded; and whatever belonging to each other they had taken in the war, or whatever other ground of difference existed between them, they came to a settlement of all such matters. And as they now arranged their measures in concert, they adopted a resolution not to receive any herald or embassy from the Athenians, unless they withdrew from the Peloponnese, and evacuated their forts;

and neither to make peace nor carry on war with any, except conjointly. And besides conducting their other measures with vehemence, they both of them sent ambassadors to the Thrace-ward towns, and to Perdiccas, whom they persuaded to join their league. He did not, however, immediately separate from the Athenians, but purposed doing so, because he saw that the Argives had also; for he himself was originally from Argos. They likewise renewed their former oaths with the Chalcidians, and bound themselves by new ones.

Moreover, the Argives sent ambassadors to the Athenians, commanding them to evacuate their fortress in Epidaurus. They therefore, seeing themselves to be but few against many who joined in garrisoning it, sent Demosthenes to lead their men out of it; who having arrived, and instituted, by way of pretext, a gymnastic contest outside the fortress, when the rest of the garrison had gone out, shut the gates upon them. Afterwards, having renewed their treaty with the Epidaurians, the Athenians by themselves gave up the fortress.