History of the Peloponnesian War

The Mantineans and their allies were the first to come over through fear of the Lacedaemonians. Having taken advantage of the war against Athens to reduce a large part of Arcadia into subjection, they thought that Lacedaemon would not leave them undisturbed in their conquests, now that she had leisure to interfere, and consequently gladly turned to a powerful city like Argos, the historical enemy of the Lacedaemonians, and a sister democracy.

Upon the defection of Mantinea the rest of Peloponnese at once began to agitate the propriety of following her example, conceiving that the Mantineans would not have changed sides without good reason, besides which they were angry with Lacedaemon among other reasons for having inserted in the treaty with Athens that it should be consistent with their oaths for both parties, Lacedaemonians and Athenians, to add to or take away from it according to their discretion.

It was this clause that was the real origin of the panic in Peloponnese, by exciting suspicions of a Lacedaemonian and Athenian combination against their liberties: any alteration should properly have been made conditional upon the consent of the whole body of the allies.

With these apprehensions there was a very general desire in each state to place itself in alliance with Argos.

In the meantime the Lacedaemonians perceiving the agitation going on in Peloponnese, and that Corinth was the author of it and was herself about to enter into alliance with the Argives, sent ambassadors thither in the hope of preventing what was in contemplation. They accused her of having brought it all about, and told her that she could not desert Lacedaemon and become the ally of Argos, without adding violation of her oaths to the crime which she had already committed in not accepting the treaty with Athens, when it had been expressly agreed that the decision of the majority of the allies should be binding, unless the gods or heroes stood in the way.

Corinth in her answer, delivered before those of her allies who had like her refused to accept the treaty, and whom she had previously invited to attend, refrained from openly stating the injuries she complained of, such as the non-recovery of Sollium or Anactorium from the Athenians, or any other point in which she thought she had been prejudiced, but took shelter under the pretext that she could not give up her Thracian allies, to whom her separate individual security had been given, when they first rebelled with Potidaea, as well as upon subsequent occasions.