Late Roman Army during the 5th century

[starman2012]

I'd be interested to know more about those doubts. Granted, army numbers in any ancient source need to be taken with considerable salt, but most sources I've come across seem to accept that the later army (at least in the 4th century) was larger.

In his How Rome Fell Goldsworthy considers the Notitia Dignitatum unreliable, and the apparent lack of resistance to various incursions evidence that much strength was just on paper.

Comparing the later army with that of the principiate is perhaps a little skewed - their military and political situations were very different. From the third century on, the empire faced massive and sustained pressure on all its frontiers, often simultaneously - coupled with periodic internal collapse, it's not surprising that the army didn't fare so well!

It fared well enough prior to c 408.

But if comparison is allowed, it might be worth considering some of the failures of the army even its earlier and more glorious days.....All these reverses were absorbed and countered, but if the enemy had possessed the strength and motivation of their third and fourth century descendents, the results could have been catastrophic.

They threatened to be catastrophic in the second century. The barbarians took advantage of weakness caused by the parthian war and plague and got as far as Italy. But Marcus restored the situation everywhere.

In other words, the Roman army was never infallible, but while the adversaries of an earlier day were unable to capitalise on their successes, those of the later era could and did - the later army only had to fail once for disaster to ensue.

It appears the key difference between the fifth century and earlier times was the lack of resilience. As you note, the Romans had always suffered severe setbacks. But they always bounced back admirably--until about 409 CE or so. Look at the terrible defeats of the mid third century, and the enemy successes--the deep, devastating raids--along key frontiers. But by 300 CE the Romans had recovered very well in the East and elsewhere. The old resilience since Cannae or earlier, was still there. For some reason, the fifth century western empire was different. It just couldn't summon the strength (i.e. of its own) to crush enemies settled on its own territory, or prevent a progressive erosion of its position.