Laudator Temporis Acti

Dionysius of Halicarnassus, Roman Antiquities 14.9.4 (tr. Earnest Cary):

For what harm can be done to men going into battle by those long locks, the fierceness of their glance, and the grim aspect of their countenances? And these awkward prancings, the useless brandishing of their weapons, the many clashings of their shields, and all the other demonstrations of barbarian and senseless bravado, whether through motions or through sounds, indulged in by way of threats to their foes—what advantage are they calculated to bring to those who attack unintelligently, or what fear to those who with cool calculation stand their ground in the midst of danger?

τί γὰρ ἂν δυνήσονται δεινὸν ἐργάσασθαι τοὺς ὁμόσε χωροῦντας αἱ βαθεῖαι κόμαι καὶ τὸ ἐν τοῖς ὄμμασιν αὐτῶν πικρὸν καὶ ὁ βλοσυρὸς τῆς ὄψεως χαρακτὴρ; αἵ τε δὴ πλημμελεῖς αὗται σκιρτήσεις καὶ τὰ διὰ κενῆς ἀνασείσματα τῶν ὅπλων καὶ οἱ πολλοὶ τῶν θυρεῶν κτύποι καὶ ὅσα ἄλλα ὑπὸ βαρβάρου καὶ ἄφρονος ἀλαζονείας κατά τε μορφὰς καὶ φωνὰς ἐν ἀπειλαῖς πολεμίων σπαθᾶται, τίνα παρέχειν πέφυκε τοῖς ἀνοήτως ἐπιοῦσι πλεονεξίαν ἢ τοῖς μετὰ λογισμοῦ παρὰ τὰ δεινὰ ἑστῶσι φόβον;

ἐργάσασθαι with double accusative (as here) = do something to. A bit more literally, "What harm can those long locks, the fierceness of their glance, and the grim aspect of their countenances do to men going into battle?"