ἐξεστρατεῦσθαι

From LSJ

ἔργοισι χρηστός, οὐ λόγοις ἔφυν μόνον → a friend in deeds, and not in words alone

Source

Greek > English (Woodhouse Verbs Reversed)

(see also ἐκστρατεύω): be on active service