This is from Diod. 15.53 ( the prelude to the Battle of Leuktra)
ὁ δὲ Κλεόμβροτος πυθόμενος τοὺς πολεμίους προκατειληφέναι τὰς παρόδους, τὸ μὲν ταύτῃ ποιεῖσθαι τὴν διέξοδον ἀπέγνω, πορευθεὶς δὲ διὰ τῆς Φωκίδος, καὶ διεξελθὼν τὴν παραθαλαττίαν ὁδὸν χαλεπὴν οὖσαν, ἐνέβαλεν εἰς τὴν Βοιωτίαν ἀκινδύνως: ἐν παρόδῳ δέ τινα τῶν πολισματίων χειρωσάμενος δέκα τριήρων ἐγκρατὴς ἐγένετο.
I'm having trouble working out why there is a τὸ in "τὸ μὲν ταύτῃ ποιεῖσθαι ". My best guess is that even though ταύτῃ is nominally a femine dative it is acting as an adverb and so is treated as neuter when made into a noun by the article but the emphasis is on guess.
This is my current translation
Kleombrotos learning that the enemy had seized in advance the passes. by means of this (way) to make the passage-through he gave-up, and he marched instead through Fokis and passing-through the by-the-sea road difficult being, invaded into Boeotia safely: