History of the Peloponnesian War

These were the quarrels and differences on either side before the war, which quarrels began presently upon the business of Epidamnus and Corcyra. Nevertheless there was still commerce betwixt them, and they went to each other without any herald, though not without jealousy. For the things that had passed were but the confusion of the articles and matter of the war to follow.

The war between the Athenians and the Peloponnesians beginneth now from the time they had no longer commerce one with another without a herald, and that having once begun it they warred without intermission. And it is written in order by summers and winters according as from time to time the several matters came to pass.

The peace, which after the winning of Euboea was concluded for thirty years, lasted fourteen years. But in the fifteenth year, being the forty-eighth of the priesthood of Chrysis in Argos, Aenesias being then ephor at Sparta and Pythadorus, archon of Athens, having then two months of his government to come, in the sixth month after the battle at Potidaea and in the beginning of the spring, three hundred and odd Thebans led by Pythangelus the son of Phyleides and Diemporus the son of Onetoridas, Boeotian rulers, about the first watch of the night entered with their arms into Plataea, a city of Boeotia and confederate of the Athenians.

They were brought in and the gates opened unto them by Naucleides and his accomplices, men of Plataea that for their own private ambition intended both the destruction of such citizens as were their enemies and the putting of the whole city under the subjection of the Thebans.

This they negotiated with one Eurymachus the son of Leontiadas, one of the most potent men of Thebes. For the Thebans, foreseeing the war, desired to preoccupy Plataea, which was always at variance with them, whilst there was yet peace and the war not openly on foot. By which means they more easily entered undiscovered, there being no order taken before for a watch.