Like the Ptolemies or Seleucids and other Hellenistic successor kingdoms, or the various incarnations of the Persian empire, or any other ancient example you can think of.
I know that the above kingdoms named their various elite regiments, like Alexander's companions or the Achaemenid Immortals, or perhaps the Seleucid Chrysaspides and Chalkaspides, but those were exceptional units. I I don't know of any kingdom or nation that had regular military units that they named, let alone numbered. When ancient historians describe armies, (e.g. Polybios in book XXXI of his histories on the Seleucids) they mostly seem to refer to groups by ethnic origin. (Nisaean horsemen, etc.) I'm not sure these historians would know of any names such groups had for themselves, though. But perhaps these were only short-standing levies which didn't get names. Do we know of any more named units?
I know the navy was very important and prestigious for the Hellenistic monarchs in particular, and I know that ships were named, but I don't know of any fleets being named. The Imperial Romans typically named them after their harbours, i.e. Classis Misenensis. Did anybody else do this?
I know that (foreign) mercenaries played a big role in various armies, (like the Persians employing Greek hoplites) but I've never heard of any being organised in named units or companies. Were they?
And on a slightly different but related note, do we know how the Roman practice of giving their legions cognomen as well as numbers started? (Legio II Augusta, Legio VI Ferrate, etc.) From the timeline and from common sense I assume it only began once units acquired a more permanent nature in the first century BC, but other than that I don't know who started it or why. I mean, the purpose of fostering unit identity is obvious enough, but do any ancient writers discuss this? Is it documented elsewhere?
Thanks to anyone indulging my curiosity!
And on a slightly different but related note, do we know how the Roman practice of giving their legions cognomen as well as numbers started? (Legio II Augusta, Legio VI Ferrate, etc.) From the timeline and from common sense I assume it only began once units acquired a more permanent nature in the first century BC
Just as a note, in point of fact the legions didn't really become permanent until after Actium, when Augustus standardized the number of legions and placed then for the first time in permanent posts. The abolition of the property qualification allowed armies to serve for more than a single campaigning season, but since magisterial terms were limited to a year and a magistrate holding imperium had to lay it down (which meant disbanding his troops, among other things) before rejoining the ranks of the senate, in point of fact armies still only lasted a year. Sulla's law allowing propraetors and proconsuls provincial commands (usually for five years) allowed armies to stay in thr field for much longer periods of time, since every promagisterial governor could rely on being given an army. But at the end of the term, when the governor had to lay down his imperium, troops were expected to be disbanded again--we encounter things like Pompey's refusal to disband his troops, or Caesar's troops who fought throughout thr civil wars illegally, but these are notable exceptions to the rule and are very much illegal. It's not until Augustus that legions are not tied to the inpweium of their commander--because of the emperor's ability to command imperium maius those legions can be stationed and maintained for decades at a time. Likewise, it's probably not until Augustus that legions begin being given permanent titles--after all, prior to this it wouldn't have made much sense, given that a legion would only hold its title for a short time before being disbanded, and any new legion raised with the same number was a different legion entirely. There are a few exceptions to that, such as Caesar's Tenth Legion (although I somewhat doubt that their title was made official until much later), but generally it stands
Unfortunately I don't think I can really help with your actual question, although we do have knowledge of contingents being named. You've mentioned things like the Immortals (they're not actually called that in Persian though), but of course we know that Alexander had named contingents of a kind, in the form of formations like the silver shields. The are, though, as you have said, somewhat special outfits, however, and that's not really what you're asking about. Battalions of the Phalanx were considered separate formations as well, and were, unlike many of his contingents (like the Thessalians, or most of his light troops), were not ethnically unique, but I'm not sure whether they had individual names--I doubt it, I've only ever seen them referred to by their commanders' names