§18.21.1ὁ δὲ Τίτος στρατοπεδεύων περὶ τὸ Θετίδειον, καὶ διαπορούμενος ὑπὲρ τῶν πολεμίων ποῦ ποτʼ εἰσί, δέκα προθέμενος οὐλαμοὺς καὶ τῶν εὐζώνων εἰς χιλίους ἐξαπέστειλε, παρακαλέσας εὐλαβῶς ἐξερευνωμένους ἐπιπορεύεσθαι τὴν χώραν· §18.21.2οἳ καὶ προάγοντες ὡς ἐπὶ τὰς ὑπερβολὰς ἔλαθον ἐμπεσόντες εἰς τὴν τῶν Μακεδόνων ἐφεδρείαν διὰ τὸ δύσοπτον τῆς ἡμέρας. §18.21.3οὗτοι μὲν οὖν ἐν ταῖς ἀρχαῖς ἐπὶ βραχὺ διαταραχθέντες ἀμφότεροι μετʼ ὀλίγον ἤρξαντο καταπειράζειν ἀλλήλων, διεπέμψαντο δὲ καὶ πρὸς τοὺς ἑαυτῶν ἡγεμόνας ἑκάτεροι τοὺς διασαφήσοντας τὸ γεγονός· §18.21.4ἐπειδὴ δὲ κατὰ τὴν συμπλοκὴν οἱ Ῥωμαῖοι κατεβαροῦντο καὶ κακῶς ἔπασχον ὑπὸ τῆς τῶν Μακεδόνων ἐφεδρείας, πέμποντες εἰς τὴν ἑαυτῶν παρεμβολὴν ἐδέοντο σφίσι βοηθεῖν. §18.21.5ὁ δὲ Τίτος, παρακαλέσας τοὺς περὶ τὸν Ἀρχέδαμον καὶ τὸν Εὐπόλεμον Αἰτωλοὺς καὶ δύο τῶν παρʼ αὑτοῦ χιλιάρχων, ἐξέπεμψε μετὰ πεντακοσίων ἱππέων καὶ δισχιλίων πεζῶν. §18.21.6ὧν προσγενομένων τοῖς ἐξ ἀρχῆς ἀκροβολιζομένοις, παραυτίκα τὴν ἐναντίαν ἔσχε διάθεσιν ὁ κίνδυνος· §18.21.7οἱ μὲν γὰρ Ῥωμαῖοι, προσλαβόντες τὴν ἐκ τῆς βοηθείας ἐλπίδα διπλασίως ἐπερρώσθησαν πρὸς τὴν χρείαν, §18.21.8οἱ δὲ Μακεδόνες ἠμύνοντο μὲν γενναίως, πιεζούμενοι δὲ πάλιν οὗτοι καὶ καταβαρούμενοι τοῖς ὅλοις προσέφυγον πρὸς τοὺς ἄκρους καὶ διεπέμποντο πρὸς τὸν βασιλέα περὶ βοηθείας.
Titus, on his part, who was encamped near Thetidium and was in doubt as to where on earth the enemy were, sent forward ten troops of cavalry and about a thousand of his light-armed infantry, instructing them to traverse the country, reconnoitring cautiously. As they advanced towards the passes, they unwittingly fell in with the Macedonian outpost, owing to the poor visibility of the day. At first, then, both parties were slightly thrown into confusion, but after a short time they began to skirmish with each other, and each side also sent messengers to their own commanders to report what had happened. But when, in the course of the engagement, the Romans were being hard pressed and suffered severely at the hands of the Macedonian outpost, they sent to their own camp, begging them to send help. Titus, having called upon the Aetolians under Archidamus and Eupolemus and two of his own military tribunes, sent them out with five hundred cavalry and two thousand infantry. When these had joined those who had been skirmishing from the first, the aspect of the combat at once took the opposite turn. For the Romans, gaining hope from the reinforcement, were doubly strengthened for the struggle, while the Macedonians defended themselves bravely, but being in their turn hard pressed and thoroughly overpowered, they fled to the summits and sent to the king for help.