History of the Peloponnesian War

Such were the navies of the Hellenes, both those of early and those of later times; nevertheless those who gave attention to such matters acquired not a little strength by reason both of revenue of money and of sway over others. For they—and especially the peoples whose own territory was insufficient—made expeditions against the islands and subjugated them.

But by land no wars arose from which any considerable accession of power resulted; on the contrary, all that did occur were border wars with their several neighbours, and foreign expeditions far from their own country for the subjugation of others were not undertaken by the Hellenes. For they had not yet been brought into union as subjects of the most powerful states, nor, on the other hand, did they of their own accord make expeditions in common as equal allies; it was rather against one another that the neighbouring peoples severally made war.