History of the Peloponnesian War

Withal it happened that the thirty years' peace with the Argives was now upon the point of expiring; and the Argives would not renew it without restitution made them of Cynuria; so that to war against the Argives and the Athenians, both at once, seemed impossible. They suspected also that some of the cities of Peloponnesus would revolt to the Argives, as indeed it came afterwards to pass.

These things considered, it was by both parts thought good to conclude a peace, but especially by the Lacedaemonians for the desire they had to recover their men taken in the island. For the Spartans that were amongst them were both of the prime men of the city and their kinsmen.

And therefore they began to treat presently after they were taken; but the Athenians, by reason of their prosperity, would not lay down the war at that time on equal terms. But after their defeat at Delium, the Lacedaemonians, knowing they would be apter now to accept it, made that truce for a year, during which they were to meet and consult about a longer time.