Passage 4.17.7
ὡς δὲ οἱ Λακεδαιμόνιοι συνέμισγον καὶ ἦσαν ἐς τὸ κατʼ αὐτοὺς οἱ Μεσσήνιοι τετραμμένοι, ἐνταῦθα Ἀριστοκράτης ἀρχομένης τῆς μάχης ἀπῆγε τοὺς Ἀρκάδας, καὶ τοῖς Μεσσηνίοις τό τε ἀριστερὸν καὶ μέσον ἠρήμωτο· οἱ γὰρ Ἀρκάδες σφίσιν εἶχον ἀμφότερα ἅτε ἀπόντων μὲν Ἠλείων τῆς μάχης, ἀπόντων δὲ Ἀργείων καὶ Σικυωνίων. προσεξειργάσθη δὲ καὶ ἄλλο τῷ Ἀριστοκράτει· διὰ γὰρ Μεσσηνίων ἐποιεῖτο τὴν φυγήν.
But when the Lacedaemonians joined battle and the Messenians were directing their attention to them, at this moment Aristocrates, as soon as the battle had commenced, withdrew the Arcadians. Thus the left wing and the centre of the Messenians were left isolated; for the Arcadians had occupied both positions, since both the Eleans were absent from the battle, as likewise were the Argives and Sicyonians. Aristocrates also committed another treachery: he directed his flight straight through the ranks of the Messenians.