τὸ ἀπιστοῦντα φανερὸν εἶναι ἀρχὴν ἡγήσατο πολέμου:
can we put the subject of the infinitive here into nominative since it is the same as the subject of the main verb?
I read through the surrounding paragraph and the preceding a couple of times, and it seems to make sense to me, though I didn’t know every word. This particular bit explains the accusative, I think:
…τὸ μὲν περιελέσθαι αὐτῶν τὰ ὅπλα καὶ ἀπολέμους ποιῆσαι ἀπεδοκίμασε, καὶ ἄδικον ἡγούμενος καὶ κατάλυσιν τῆς ἀρχῆς ταύτην νομίζων· τὸ δʼ αὖ μὴ προσίεσθαι αὐτοὺς καὶ τὸ ἀπιστοῦντα φανερὸν εἶναι ἀρχὴν ἡγήσατο πολέμου…
It seems to me that the articular infinitives and ἀπεδοκίμασε depersonalize it a bit. He’s rejecting these first options as things he would not do and the hypothetical ἀπιστοῦντα is distanced from himself as the subject of ἡγήσατο. Had the preceding τό + infinitives been phrased in some more personal way, maybe ἀπιστοῦντα would have come out nominative.
I think I got it: he thinks that the beginning of war is to appear suspicious: initiuim belli esse suspiciosum se videri putat. This does not belong to Sm 1974 but to indirect speech: ἀπιστοῦντα φανερὸν is the predicate of ἀρχὴν that is why it is also in acc
I hope someone will correct my Latin.