Passage 9.6.1
τῶν δέ σφισιν ἐν ἀγῶσι πολέμου γενομένων εὐτυχημάτων, καὶ ὡς ἑτέρως, τοσάδε φανερώτατα ὄντα εὕρισκον. ἐκρατήθησαν ὑπὸ Ἀθηναίων μάχῃ Πλαταιεῦσιν ἀμυνάντων, ὅτε σφᾶς ἐπέλαβεν ὑπὲρ τῶν ὅρων πολεμῆσαι τῆς χώρας· προσέπταισαν δὲ καὶ δεύτερον Ἀθηναίοις ἀντιταξάμενοι περὶ Πλάταιαν, ἡνίκα δοκοῦσιν ἑλέσθαι τὰ βασιλέως Ξέρξου πρὸ τῶν Ἑλληνικῶν.
Among the successes occurring for them in contests of war, as well as events of the opposite kind, I find the following to have been most conspicuous: They were defeated by the Athenians in a battle, in which the Plataeans joined to defend themselves, when they attempted to wage war over disputed boundaries of the land; and they suffered another reverse, again opposed by the Athenians near Plataea, precisely at the time when they thought themselves about to seize the side of King Xerxes against the interests of Greece.