Thucydides, History of the Peloponnesian War
Benjamin Jowett, Ed.

85. At last, when the dead bodies were lying in heaps upon one another in the water and the army¹ was utterly undone, some perishing in the river, and any who escaped being cut off by the cavalry, Nicias surrendered to Gylippus, in whom he had more confidence than in the Syracusans. He entreated him and the Lacedaemonians to do what they pleased with himself, but not to go on killing the men. [2] So Gylippus gave the word to make prisoners. Thereupon the survivors, not including however a large number whom the soldiers concealed, were brought in alive. As for the three hundred who had broken through the guard in the night, the Syracusans sent in pursuit and seized them. [3] The total of the public prisoners when collected was not great; for many were appropriated by the soldiers, and the whole of Sicily was full of them, they not having capitulated like the troops under Demosthenes. [4] A large number also perished; the slaughter at the river being very great, quite as great as any which took place in the Sicilian war; and not a few had fallen in the frequent attacks which were made upon the Athenians during their march. Still many escaped, some at the time, others ran away after an interval of slavery, and all these found refuge at Catana.