ἐτύγχανον. . . ὄντες: idiom, Englished as "It happened that . . . they wereἐτύγχανον δὲ καὶ δυνάμει αὐτῶν οἱ πλείους πρῶτοι ὄντες τῆς πόλεως.
δυνάμει: "with respect to political influence" [back in Corcyraea]
*αὐτῶν οἱ πλείους πρῶτοι ὄντες:
"of the prisoners [ αὐτῶν] the greater part [ οἱ πλείους ] were [ ὄντες] among the most influential [πρῶτοι]".
*To form this understanding, i studied the LCL translation, and then stepped through the phrase word-by-word . I often stumble on phrases of this kind (in Greek and Latin) when I don't see how the inflected words fit together to produce a meaning. I wonder if this difficulty fades slowly with practice. Or, is there a more systematic way to learn this more quickly?
I'll add that I was pretty sure that I had a vague general meaning, that "these prisoners were VIPs back in Corcyraea". But I didn't see the relations among the Greek words.