History of the Peloponnesian War

On the arrival of the men with Salaethus, the Athenians immediately put the latter to death, though he held out certain promises, and amongst others, that he would obtain the retreat of the Peloponnesians from Plataea (for it was still being besieged):

but respecting the former they deliberated what to do; and in their anger they determined to put to death, not only those that were there, but all the Mytilenaeans also that were of age; and to make slaves of the women and children. For they both urged against them [the aggravated character of] their revolt in other respects, namely, that they had executed it without being subject to their dominion, like the rest; and the fact of the Peloponnesian ships having dared to venture over to Ionia to assist them, contributed also no little to their wrath;