History of the Peloponnesian War
Thucydides
Thucydides. History of the Peloponnesian War. Crawley, Richard, translator. London and Toronto: J. M. Dent and Sons Ltd.; New York: E. P. Dutton and Co., 1914.
Here, also, Conon came to them, the commander at Naupactus, with news that the twenty-five Corinthian ships stationed opposite to him, far from giving over the war, were meditating an engagement; and he therefore begged them to send him some ships, as his own eighteen were not a match for the enemy's twenty-five.
Demosthenes and Eurymedon, accordingly, sent ten of their best sailors with Conon to reinforce the squadron at Naupactus, and meanwhile prepared for the muster of their forces; Eurymedon, who was now the colleague of Demosthenes, and had turned back in consequence of his appointment, sailing to Corcyra to tell them to man fifteen ships and to enlist heavy infantry; while Demosthenes raised slingers and darters from the parts about Acarnania.
Meanwhile the envoys, already mentioned, who had gone from Syracuse to the cities after the capture of Plemmyrium, had succeeded in their mission, and were about to bring the army that they had collected, when Nicias got scent of it, and sent to the Centoripae and Alicyaeans and other of the friendly Sicels, who held the passes, not to let the enemy through, but to combine to prevent their passing, there being no other way by which they could even attempt it, as the Agrigentines would not give them a passage through their country.
Agreeably to this request the Sicels laid a triple ambuscade for the Siceliots upon their march, and attacking them suddenly, while off their guard, killed about eight hundred of them and all the envoys, the Corinthian only excepted, by whom fifteen hundred who escaped were conducted to Syracuse.
About the same time the Camarinaeans also came to the assistance of Syracuse with five hundred heavy infantry, three hundred darters and as many archers, while the Geloans sent crews for five ships, four hundred darters and two hundred horse.