E.C. Marchant, Commentary on Thucydides: Book 6

εὐθύς—without waiting for the prisoners to be got on board and for the army to start; possibly also without waiting for the fall of Hyccara. (The narrative is obscure here.)

ἀπέδοσαν—the act. (see crit. note) certainly cannot= ‘sold,’ but must mean ‘gave back’ or ‘paid’ or ‘delivered.’ Grote says it ‘seems to mean that the prisoners were handed over to their fellow-countrymen, the natural persons to negotiate for their release, upon private contract of a definite sum,’ but this does not suit παρῆν ἐς τὸ στράτευμα. Bloomfield thinks ‘exposed for sale’is a possible meaning of the active. The difficulty really comes from the obscurity of the passage that precedes. If Nicias left Hyccara before it fell, and rejoined the main fleet on the way back to Catana, ἀπέδοσαν may mean ‘they delivered the prisoners to Nicias.’ ἐγένοντο ἐξ αὐτῶν is enough to show that they were then sold.

ἐγένοντο—the plur. verb with neut. subject, not persons, appears in all MSS. only in v. 75 Καρνεῖα ἑτυγχανον όντα, v. 26 ἁμαρτήματα ἐγένοντο, and here. In I. 126 ἐπῆλθον Ὀλύμπια CEG read ἐπῆλθεν, and in II. 8 λόγια ἐγένοντο CG read ἐγένετο. ἀπέλυσαν for ἀπέδοσαν Argyriades.