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.
Moreover, the Peloponnesians went down to the water's edge and butchered them, especially those in the river. The water at once became foul, but was drunk all the same, although muddy and dyed with blood, and indeed was fought for by most of them.
At length, when the dead[*](Thucydides is silent as to the number of the slain. Diodorus (xviii. 19) puts the loss at the river at 18,000 and the captured at 7000; but it is evident that he includes the army of Demosthenes.) now lay in heaps one upon the other in the river, and the army had perished utterly, part in the river, and part—if any got safely across—at the hands of the cavalry, Nicias surrendered himself to Gylippus, having more confidence in him than in the Syracusans; and he bade him and the Lacedaemonians do with himself whatever they pleased, but to stop slaughtering the rest of the soldiers. Whereupon Gylippus at last gave orders to make prisoners;