Late Roman Army Questions

[Nathan Ross]

Did the Limitanei ever work directly with the field armies of Comitatenses?

The formal division between Comitatus and frontier units seems to date from the mid 4th century at the earliest - before that, there was interchange between the two. Most of our sources relate to the activities of imperial field armies in times of large-scale campaigning, and so the frontier troops are seldom mentioned, but I would think it inevitable that they cooperated.

Ammianus Marcellinus (28.5) describes an invasion of Saxons into Gaul in c.370 countered first by Nannienus, comes, "who was in command in that district", and then, after some Roman losses, by the magister peditum Severus, who arrived with reinforcements: an example of comitatensis troops being used in support of (probably) limitanei.

What would be a standard line up of a roman army of the period? Similar to earlier periods with Auxiliary units on the flanks, legions in the center?

Ammianus's description of Julian's array at the battle of Strasbourg (AD357) seems to suggest so. Julian placed his legionary infantry in the centre, with auxilia palatina units - Cornuti, Bracchiati and others - on the flanks and the cavalry on the extreme right, with a strong central legionary reserve of the Primani in the second line.

The auxilia, however, were not the same as the 'auxiliaries' of the earlier empire (despite Ammianus using the same term to describe both, and also barbarian allies!). They were elite front-line infantry of the field army. Some of the old 'auxiliary' cohorts and cavalry alae still existed in frontier garrisons, although we don't have much evidence of their use.

Did different legions/units have unique shields?

Apparently so. The Notitia Dignitatum (a late 4th / early 5th register of imperial offices) provides illustrations of most of them, although we have no way of telling how accurate it may have been!

You can find them all illustrated and annotated here: Late Roman Shield Patterns from the Notitia Dignitatum

Where would the Foederati of the late army stand on the battlefield?

This would depend on 'late' you want to take things! In earlier armies they probably took the flanks. Things might have changed by the 5th century though...

Is there an accurate list of all the late army units, types of units, legions etc?

The Notitia Dignitatum (see above) is certainly a list, and very detailed. But, as I say, opinions are divided on its accuracy! There's plenty of stuff about it online, though, so you can form your own opinion.

Meanwhile, you might be interested in these blog posts, which give a general overview of the army of the earlier 4th century:

The Roman Army of Constantine, Part 1

The Roman Army of Constantine, Part 2