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 some states, but only a few, came over. Afterwards, however, an agreement was made with all the rest of the troops under Demosthenes that if they would surrender their arms no one should suffer death either by violence or by imprisonment or by deprivation of the bare necessities of life.
So they all surrendered, six thousand in number; and they gave up all the money they had, casting it into upturned shields; and four of these were filled. These captives the Syracusans immediately took to the city; as for Nicias and his men, they reached the river Erineus that same day, and after crossing it Nicias encamped his army on a height.
The next day[*](Seventh day of the retreat.) the Syracusans overtook Nicias and told him that the troops under Demosthenes had surrendered, bidding him do likewise; but Nicias was incredulous, and obtained a truce that he might send a horseman and find out.
And when the horseman had gone and brought back word that they had indeed surrendered, Nicias announced by herald to Gylippus and the Syracusans that he was ready to agree, on behalf of the Athenians, to repay to the Syracusans all the money which they had spent upon the war, on condition that they should let his army go; and until the money should be paid, he would give Athenians as hostages, one man for each talent.
Gylippus and the Syracusans, however, would not accept these terms, but renewing the attack and surrounding the Athenian army plied these men also with their missiles until evening.
And they were in a wretched plight through want of food and of all necessaries. Nevertheless they waited for the quiet time of night and intended then to proceed. But no sooner had they taken up their arms than the Syracusans perceived it and raised the paean.