Passage 7.15.8
ἐνταῦθα ὁ Δίαιος ἐς ἅπαν ἀφίκετο ἀνοίας, ὃς Κριτόλαον καὶ πᾶσαν τὴν Ἀχαιῶν ἐπιστάμενος παρασκευὴν κακῶς οὕτως ἀγωνισαμένην πρὸς Μέτελλον ἀπέλεξεν αὐτὸς ὅσον τετρακισχιλίους· καὶ ἄρχοντα ἐπʼ αὐτοῖς ἔταξεν Ἀλκαμένην. ἀπεστέλλοντο δὲ ἐς Μέγαρα φρουρά τε εἶναι Μεγαρεῦσι τοῦ ἄστεως καί, ἢν Μέτελλος ἐπίῃ καὶ οἱ Ῥωμαῖοι, τοῦ πρόσω σφᾶς κωλύειν.
At this point, Diaeus reached the extreme of folly; for though fully aware that Critolaus and all the forces of the Achaeans had fought disastrously against Metellus, he himself chose out about four thousand men and appointed Alcamenes as commander over them. They were sent off to Megara both to guard the city for the Megarians and, in case Metellus and the Romans advanced, to prevent their further progress.