History of the Peloponnesian War

The Corcyraeans, though not only Dorians but even Corinthians, followed openly against the Corinthians and Syracusans, though colonists of the one and kinsmen of the other; by compulsion, according to their specious profession, but rather with good will, for the hatred they bore the Corinthians. The Messenians, too, as they are now called, at Naupactus, and also from Pylus, which was then held by the Athenians, were taken to the war. Moreover, some few Megarean exiles, owing to their misfortune, were fighting against the Selinuntines, who were Megareans.

Of the rest the service was now more of a voluntary nature. For it was not so much on account of their alliance, as out of hatred for the Lacedaemonians, and for their own individual advantage at the moment, that the Argives followed in company of the Ionian Athenians to fight as Dorians against Dorians.

While the Mantineans, and other mercenaries from Arcadia, went as being accustomed to go against the enemies who at any time were pointed out to them; and thought, for the sake of gain, that the Arcadians, who at that time came with the Corinthians, were no less than others their foes. The Cretans and Aetolians also came for consideration of pay; and it happened in the case of the Cretans, that although they had joined the Rhodians in founding Gela, they now came, not with their colonists, but against them—not by choice, but for pay. There were also some Acarnanians who served as auxiliaries, partly from motives of interest, but mainly as being allies, through their friendship with Demosthenes, and their good-will towards the Athenians.