RECONSTRUCTION OF THE PROPOSED READING FOR THE L. ARTORIUS CASTUS LACUNA

Once again, the /G/ for GENTE was taken from the line immediately below the line of the lacuna.  My measurement shows that this line is of exactly the same width as the line above it.

The /E/ plus triple ligature NTE was taken from the end of the same line, where we have CENTE.

The resulting reading would require an interpunct between the /M/ and the /G/.  The inscription has quite a few interpuncts, and we can see one between the /S/ and the following ARM of the lacuna.

The sense of ARM.GENTES would be "arm(atas) gentes" or "armed tribes."  Given the Arthurian battles as I have arranged them on the map, and the presence of the Caledonian Wood and the Maeatae/Miathi in both the HB and in the tradition regarding the Dalriadan Arthur, my best guess for the tribes in question are the Caledonii and Maeatae confederacies.  These tribal groups were subject to two intensive, large-scale campaigns by the Emperor Severus.

Once Severus had died and Caracalla took over, the northern campaign was put to an end.  Caracalla had to deal with new Germanic invasions north of Rome and it would have been at this time that Castus was appointed procurator of Liburnia with the right of the sword.  

This reading and the chronology of the Severan campaign in Britain fits the age estimate for the Castus inscription according to Benet Salway and Abigail Graham, as well as other epigraphers.

As Castus was prefect of the Sixth Legion, a legion based at York whose task was to guard the North, reference to armed tribes is unlikely to refer to conflict in any other part of Britain.  In addition, had the said tribes been outside of Britain Castus would have told us so.