Passage 10.1.11
εὑρέθη δὲ καὶ ὕστερον τοῖς Φωκεῦσιν οὐκ ἀποδέον σοφίᾳ τῶν προτέρων. ὡς γὰρ δὴ τὰ στρατόπεδα ἀντεκάθητο περὶ τὴν ἐς τὴν Φωκίδα ἐσβολήν, λογάδες Φωκέων πεντακόσιοι φυλάσσοντες πλήρη τὸν κύκλον τῆς σελήνης ἐπιχειροῦσιν ἐν τῇ νυκτὶ τοῖς Θεσσαλοῖς, αὐτοί τε ἀληλιμμένοι γύψῳ καὶ ἐνδεδυκότες ὅπλα λευκὰ ἐπὶ τῇ γύψῳ. ἐνταῦθα ἐξεργασθῆναι φόνον τῶν Θεσσαλῶν λέγεται πλεῖστον, θειότερόν τι ἡγουμένων ἢ κατὰ ἔφοδον πολεμίων τὸ ἐν τῇ νυκτὶ συμβαῖνον. ὁ δὲ Ἠλεῖος ἦν Τελλίας ὃς καὶ ταῦτα τοῖς Φωκεῦσιν ἐμηχανήσατο ἐς τοὺς Θεσσαλούς.
Later the Phocians devised a stratagem no less ingenious than their forebears. When the opposing armies were encamped facing each other near the entrance to Phocis, five hundred select Phocian troops, waiting until the night of the full moon, made a sudden attack upon the Thessalians during the darkness. They had covered their own bodies with gypsum and wore white armor over this coating. It is said that the Thessalians suffered a very great slaughter, for they imagined that what befell them in the darkness was due rather to some divine visitation than to a human attack by enemies. This stratagem used by the Phocians against the Thessalians was devised by Tellias the Elean.