τῷ γέ?οντι χά?ιν ἔχομεν. - ok
At night they ceased from battle.
τῇ νυκτὶ τοῦ πόλεμου κατέλειψαν.
Rather : τῆς νυκτὸς (see 256) ?πα?σαντο (< πα?ομαι with the Gen., see 189 and 849) τῆς μάχης.
Cyrus had twenty chariots
Κῦ?ος ἄ?ματα εἴκοσιν εἶχεν. (I modified the accent on εἶχεν)
The bowmen shot birds and wild asses on the plain.
οἱ τοξόται ?ν τῷ πεδίῳ ὄ?νιθας καὶ ὄνους ἀγ?ίους ?τόξευσαν.
The army was cut to pieces by the barbarians.
κατακέκοπται τῇ στ?ατιᾷ οἱ βά?βα?οι.
I would say : κατεκόπη (aorist passive) ἡ στ?ατιὰ (subject) ὑπὸ τῶν βα?βά?ων (agent)