I was looking again at the 'army list' for my 1,000 point Roman force. I am not sure about the lanciarii being 'light' infantry - indeed, I'm not even sure they're all infantry - some at least, seem to have been cavalry. I just can't decide how to treat them - the more I read, the more confused I become - maybe I'll just assume that the spear-armed guys in the back ranks of my legionary cohorts are in some sense lanciarii. But as for using units of 'legionary light infantry', I rather think not (or do I?) - the evidence is, at best, even more fragmentary than usual.
Those particular waters are rather muddy, particularly when one considers a tombstone such as that of Valerius Tertius:
"...served in a Moesian legion for five years, in the lanciarii for eleven years, in the praetorian guard for..."
Which seems to suggest that the lanciarii may have been separated in some way from the 'hoi polloi' of the legions - though the date of the tombstone is perhaps a bit late even for my Third Century project - though presumably his service must date from before Constantine abolished the Praetorians.
And, of course, there is Herodian's 'History of the Roman Empire', particularly book 4, chapter XV:
"The Romans had arranged their divisions carefully to insure a stable front; the cavalry and the Moroccan javelin men were stationed on the wings, and the open spaces were filled with light-armed and mobile troops that could move rapidly from one place to another."
Are these 'light-armed and mobile' troops lanciarii, auxilia, or what? I suppose one could argue it any of several ways! And how to model them in WAB terms? Skirmishers, obviously enough, but what sort of skirmishers?
In the absence of an irresistibly compelling argument in any particular direction, I am going to adopt the ostrich position, and ignore Lanciarii for now! So, I am minded to change my army list a little and replace the 'cohort' of lanciarii with a cohort of auxilia. My army definitely needs auxilia: they were an important part of the army, although by this date, they were hard to distinguish, at least where equipment is concerned, from their fellows in the legions - see my post from 15th August.
I am, at some point, going to try to model Cohors XX Palmyrenorum Equitata Milliaria - which was part of the garrison of Dura Europos. It was a '1,000 strong' mixed cohort - so ostensibly consisting of ten centuries of 80 infantry and eight turmae of 30 cavalry, though Cohors XX Palmyrenorum was unusual in having a small number of dromedarii on the strength as well. Could be fun to model, and try to wargame with! Maybe those 'lanciarii' could be swapped for the start of this particular cohort.
On the other hand, at some stage a whole unit of camels could be fun - and there is evidence for the existence, in Syria, of a unit consisting of just that: Ala I Ulpia Dromedariorum Milliaria.