History of the Peloponnesian War

These were the charges and differences that each side had before the war, beginning from the very time of the affairs at Epidamnus and Corcyra. Nevertheless they continued to have intercourse during them, and to go to each other's country without any herald, though not without suspicion; for what was taking place served to break up the treaty, and was a pretext for war.

The war between the Athenians and Peloponnesians and their respective allies now begins from this period, at which they ceased from further intercourse with each other without a herald, and having once proceeded to hostilities, carried them on continuously; and the history of it is written in order, as the several events happened, by summers and winters.

For the thirty years' truce which was made after the reduction of Euboea lasted fourteen years; but in the fifteenth year, when Chrysis was in the forty-eighth year of her priesthood at Argos, and Aenesias was ephor at Sparta, and Pythodorus had still two months to be archon at Athens; in the sixth month after the battle at Potidaea, and in the beginning of spring, rather more than three hundred men of the Thebans, (led by Pythangelus, son of Phylidas, and Diemporus, son of Onetorides, Boeotarchs,) about the first [*]( Literally first sleep. ) watch entered with their arms into Plataea, a town of Boeotia, which was in alliance with the Athenians.

There were certain men of the Plataeans who called them in, and opened the gates to them, namely, Nauclides and his party, who wished, for the sake of their own power, to put to death those of the citizens who were opposed to them, and to put the city into the hands of the Thebans.

They carried on these negotiations through Eurymachus, the son of Leontiades, a very influential person at Thebes. For the Thebans, foreseeing that the war would take place, wished to surprise Plataea, which had always been at variance with them, while it was still time of peace, and the war had not openly broken out. And on this account, too, they entered the more easily without being observed, as no guard had been set before [the gates].