Passage 7.6.7
ἡ δὲ ἐς Θερμοπύλας ἐπὶ τὴν Γαλατῶν στρατιὰν ἔξοδος καὶ τοῖς πᾶσιν ὁμοίως παρώφθη Πελοποννησίοις· ἅτε γὰρ πλοῖα οὐκ ἐχόντων τῶν βαρβάρων, δεινὸν ἔσεσθαί σφισιν ἀπʼ αὐτῶν οὐδὲν ἤλπιζον, εἰ τὸν Κορινθίων ἰσθμὸν ἐκ θαλάσσης τῆς κατὰ Λέχαιον ἀποτειχίσειαν ἐς τὴν ἑτέραν τὴν ἐπὶ Κεγχρέαις θάλασσαν.
The Peloponnesians likewise neglected entirely the campaign against the Galatians at Thermopylae. Since the barbarians had no ships, the Peloponnesians thought they had nothing serious to fear from them, assuming they fortified the Isthmus of Corinth from the sea facing Lechaeum to the other sea facing Cenchreae.