Six Numeri for Honorius

[Nathan Ross]

also the change to see the residue of units being hauled around!

Yes. I wonder if the various 'numeri' that appear as garrison troops in Gaul and occasionally in Britain might in fact be the residue of former comitatensis units of the field army? There doesn't seem to have been much of a field army left in Gaul after c.400, but presumably Constantius III might have re-mobilised some of the static limitanei units? (I know all this has been debated ad nauseum, by the way - but much of the scholarship is in German!)

the spring of 408, just after Arcadius' death, when Stilicho was planning to attack Constantine III with the help of Alaric?

That would make sense - the threat of an actual usurper taking over the west might have spurred Constantinople to offer some assistance to Honorius... Regular roman armies of the 5th century do seem to have been happier fighting each other than fighting barbarians!

If Constantine III was already controlling the Provence, how would the troops have reached Spain?

I was assuming that the 'Spanish operation' would have been after Constantius III's defeat of Constantine III, the Visigoths' brief occupation of Narbo and the defeat of Jovinus, and the Visigoths' subsequent moves first into Spain and then back into Aquitaine. So between about 416 and 420 or so.

By that time the central Roman authorities would have controlled a broad swathe of territory from northern Italy across the Pyrennes, and with a small mobile army based perhaps in Arles or Narbo they could have exerted control over the Goths to the north-west and the Vandals/Alans in Spain. Or so they hoped, perhaps!