History of the Peloponnesian War

On their arrival the Boeotians reported to the Boeotarchs what had been said to them at Lacedaemon and also by the Argives who had met them, and the Boeotarchs, pleased with the idea, embraced it with the more eagerness from the lucky coincidence of Argos soliciting the very thing wanted by their friends at Lacedaemon.

Shortly afterwards ambassadors appeared from Argos with the proposals indicated; and the Boeotarchs approved of the terms and dismissed the ambassadors with a promise to send envoys to Argos to negotiate the alliance.

In the meantime it was decided by the Boeotarchs, the Corinthians, the Megarians, and the envoys from Thrace first to interchange oaths together to give help to each other whenever it was required and not to make war or peace except in common; after which the Boeotians and Megarians, who acted together, should make the alliance with Argos.