History of the Peloponnesian War

This was the Thebans' purpose. But the Plataeans, whilst they were yet in council, suspecting that some such thing would be done and fearing their case without, sent a herald unto the Thebans whom they commanded to say that what they had already done, attempting to surprise their city in time of peace, was done wickedly, and to forbid them to do any injury to those without, and that otherwise they would kill all those men of theirs that they had alive, which, if they would withdraw their forces out of their territory, they would again restore unto them.

Thus the Thebans say, and that the Plataeans did swear it. But the Plataeans confess not that they promised to deliver them presently but upon treaty if they should agree, and deny that they swore it.

Upon this the Thebans went out of their territory; and the Plataeans, when they had speedily taken in whatsoever they had in the country, immediately slew their prisoners. They that were taken were one hundred and eighty; and Eurymachus, with whom the traitors had practised, was one.

When they had done, they sent a messenger to Athens and gave truce to the Thebans to fetch away the bodies of their dead, and ordered the city as was thought convenient for the present occasion.

The news of what was done coming straightway to Athens, they instantly laid hands on all the Boeotians then in Attica and sent an officer to Plataea to forbid their farther proceeding with their Theban prisoners till such time as they also should have advised of the matter; for they were not yet advertised of their putting to death.