§2.2.1τέσσαρα μὲν γὰρ καὶ δέκα ἔτη ἐνέμειναν αἱ τριακοντούτεις σπονδαὶ αἳ ἐγένοντο μετ’ Εὐβοίας ἅλωσιν· τῷ δὲ πέμπτῳ καὶ δεκάτῳ ἔτει, ἐπὶ Χρυσίδος ἐν Ἄργει τότε πεντήκοντα δυοῖν δέοντα ἔτη ἱερωμένης καὶ Αἰνησίου ἐφόρου ἐν Σπάρτῃ καὶ Πυθοδώρου ἔτι δύο μῆνας ἄρχοντος Ἀθηναίοις, μετὰ τὴν ἐν Ποτειδαίᾳ μάχην μηνὶ ἕκτῳ καὶ ἅμα ἦρι ἀρχομένῳ Θηβαίων ἄνδρες ὀλίγῳ πλείους τριακοσίων (ἡγοῦντο δὲ αὐτῶν βοιωταρχοῦντες Πυθάγγελός τε ὁ Φυλείδου καὶ Διέμπορος ὁ Ὀνητορίδου) ἐσῆλθον περὶ πρῶτον ὕπνον ξὺν ὅπλοις ἐς Πλάταιαν τῆς Βοιωτίας οὖσαν Ἀθηναίων ξυμμαχίδα.
For the Thirty Years' Peace, which was concluded after the conquest of Euboea, lasted for fourteen years; but in the fifteenth year, when Chrysis had been priestess at Argos for forty-eight years, and Aenesias was ephor at Sparta, and Pythodorus had still two months to rule as archon at Athens, in the sixth month after the battle at Potidaea, and at the beginning of spring, a little more than three hundred Thebans (led by Pythangelus son of Phyleides and Diemporus son of Onetorides, who were Boeotarchs) entered about the first watch of the night with arms into Plataea in Boeotia, which was an ally of the Athenians.
§2.2.2ἐπηγάγοντο δὲ καὶ ἀνέῳξαν τὰς πύλας Πλαταιῶν ἄνδρες, Ναυκλείδης τε καὶ οἱ μετ’ αὐτοῦ, βουλόμενοι ἰδίας ἕνεκα δυνάμεως ἄνδρας τε τῶν πολιτῶν τοὺς σφίσιν ὑπεναντίους διαφθεῖραι καὶ τὴν πόλιν Θηβαίοις προσποιῆσαι.
They were introduced, and the gates of Plataea were opened to them, by certain Plataeans, Naucleides and his party, who wished, for the sake of their own power, to destroy those of their fellow citizens who were opposed to them, and to bring the city over to the Thebans.
§2.2.3ἔπραξαν δὲ ταῦτα δι’ Εὐρυμάχου τοῦ Λεοντιάδου, ἀνδρὸς Θηβαίων δυνατωτάτου.
They accomplished this through the agency of Eurymachus son of Leontiades, a man of great influence among the Thebans.
προϊδόντες γὰρ οἱ Θηβαῖοι ὅτι ἔσοιτο ὁ πόλεμος ἐβούλοντο τὴν Πλάταιαν αἰεὶ σφίσι διάφορον οὖσαν ἔτι ἐν εἰρήνῃ τε καὶ τοῦ πολέμου μήπω φανεροῦ καθεστῶτος προκαταλαβεῖν.
For the Thebans, foreseeing that war would come, wished to pre-occupy Plataea, which had always been hostile to them, while peace was still intact and before the war had openly broken out.
ᾗ καὶ ῥᾷον ἔλαθον ἐσελθόντες, φυλακῆς οὐ προκαθεστηκυίας.
For this reason also, they escaped notice more easily in entering, since no guard had been set beforehand.
§2.2.4θέμενοι δὲ ἐς τὴν ἀγορὰν τὰ ὅπλα τοῖς μὲν ἐπαγαγομένοις οὐκ ἐπείθοντο ὥστε εὐθὺς ἔργου ἔχεσθαι καὶ ἰέναι ἐπὶ τὰς οἰκίας τῶν ἐχθρῶν, γνώμην δ’ ἐποιοῦντο κηρύγμασί τε χρήσασθαι ἐπιτηδείοις καὶ ἐς ξύμβασιν μᾶλλον καὶ φιλίαν τὴν πόλιν ἀγαγεῖν (καὶ ἀνεῖπεν ὁ κῆρυξ, εἴ τις βούλεται κατὰ τὰ πάτρια τῶν πάντων Βοιωτῶν ξυμμαχεῖν, τίθεσθαι παρ᾽ αὑτοὺς τὰ ὅπλα), νομίζοντες σφίσι ῥᾳδίως τούτῳ τῷ τρόπῳ προσχωρήσειν τὴν πόλιν.
Having grounded their arms in the marketplace, they did not follow the advice of those who had introduced them, which was to set to work at once and go to the houses of their enemies; instead, they resolved to make conciliatory proclamations and to bring the city rather to an agreement and friendship. (And the herald proclaimed that if anyone wished to be an ally according to the ancestral customs of all the Boeotians, he should place his arms beside them), thinking that in this way the city would easily come over to them.