History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
And indeed the struggle was a worthy one, both in these respects and because they were showing themselves superior, not to the Athenians only, but to their numerous allies as well, and that too not standing alone but associated with the friends who had come to their aid, thus taking their place as leaders along with the Corinthians and Lacedaemonians, having also given their own city to bear the brunt of the danger and taken a great step forward in sea-power.
Indeed, a larger number of nations than ever before had gathered together at this one city, if one except the vast throng of those who in this war rallied to the support of the city of Athens and the city of the Lacedaemonians.
For the following nations on either side had entered the war at Syracuse, coming against Sicily or in behalf of Sicily, to aid the Athenians to win the country or the Syracusans to save it; and they chose sides, not so much on the ground of right or even of kinship, but either out of regard for their own advantage or from necessity, according to the circumstances in which they each happened to be placed.[*](Or, by adopting Heilmann's and Boehme's conjecture ὡς ἕκαστοι τῆς ξυντυχίας. . . εἶχον, “severally choosing their side, not so much from a sense of right or from obligations of kinship, as from the accident of compulsion or their own interest.”)
The Athenians themselves, as Ionians, went of their own free will against the Syracusans, who were Dorians, and with them went as members of the expedition the Lemnians, the Imbrians,[*](cf. 4.28.4. The occupation of Lemnos was effected by Miltiades a few years after the battle of Marathon (Herod. VI. 137-140), that of Imbros probably about the same time; of Aegina in 431 B.C. (2.27.1); of Hestiaea in 446 B.C. (1.114.5).) and the Aeginetans, who at this time held Aegina, as also the Hestiaeans who inhabit Hestiaea in Euboea, all these being colonists of the Athenians and having the same language and institutions as they had.