Roman helmets: Imperial Gallic/Italic and Ridge - comparisons and sources

[CaesarAugustus]

we can safely agree with Goldsworthy.

We might bear in mind Adrian Goldsworthy's particular thesis about the later western empire (laid out in The Fall of the West, 2009), which suggests that the crisis of the third century damaged Roman power irrevocably, and that the 4th century, rather than being a return to strength and stability, was merely an illusory revival before a terminal decline. The supposed poor quality of later Roman arms and armour would fit with this thesis. However, the thesis itself, while very well argued, is by no means uncontroversial, and I would say the majority of scholars on late antiquity would see things otherwise.

As for helmets in particular, I would ask (again) why a Roman state that was well organised (evidenced by the fabricae etc), wealthy (evidenced by laws on gilded or silvered helmets, and in fact surviving many helmets being gilded or showing traces of gold) and effective (evidenced by the record of the later Roman army in winning battles pretty consistently up to Adrianople) would intentionally equip its hundreds of thousands of soldiers with helmets inferior to those used previously - this would include, of course, elite units of palatinae and scholae - and then continue making and using these inferior helmets, apparently exclusively, for around 150 years?

If older pattern single-bowl helmets were 'better' than ridge helmets, the Romans would have made them instead. The sheer number of Montefortino and Coolus types surviving today, for example, indicate that they were not difficult or overly expensive to produce.

I have given a technical explanation, the only thing that I can do more here is to introduce the equations.
For the reason, it is likely to be the same for which the lorica segmentata has been abandoned after more than two centuries to come back to a previous protection that was offering... less protection. It is quite clear that the army organization was decreasing overall. Centralization is not a good thing, if you lose the ability to operate in the field. It is something that you experiment when you have exceeded the peak of development and you are on the downhill section. And this is a reflection of the social crisis that the empire was experiencing.