The first to enter the alliance offered by the Argives to any Hellenes who were willing to1
accept it were the Mantineans and their allies, who joined through fear of the Lacedaemonians. For, during the war with Athens, they had subjected a part of Arcadia, which they thought that the Lacedaemonians, now that their hands were free, would no longer allow them to retain. So they gladly joined Argos, reflecting that it was a great city, the constant enemy of Sparta, and, like their own, governed by a democracy.
When Mantinea seceded, a murmur ran through the other states of Peloponnesus that they must secede too; they imagined that the Mantineans had gone over to the Argives because they had better information than themselves, and also they were angry with the Lacedaemonians, chiefly on account of that clause in the treaty with Athens which provided that the Lacedaemonians and Athenians, if agreed, might add to or take away from it whatever they pleased2
This clause aroused great uneasiness among the Peloponnesians, and made them suspect that the Lacedaemonians meant to unite with the Athenians in order to enslave them3
; they argued that the power of altering the treaty ought to have been given only to the whole confederacy.
Entertaining these fears they generally inclined towards Argos, and every state was eager to follow the example of Mantinea and form an alliance with her.