Changes in the Roman Army

[Frank]

Now, to therefore address Frank's point succinctly....

The Later Roman drift (and then Byzantine), and indeed change, towards the tactics they chose to use were influenced by the enemies they faced - particularly more and more cavalry oriented. Hence they went back to predominantly spear use and, also with the enemies, required greater bow use.

None of those changes, however, necessarily required a basic change to the unit organisations (all of which were embedded in tried and tested logistic support functions - I will also suggest people never forget as even real-life Generals rather like to!). Things could have changed and there is some evidence of minor change; but I do intend to suggest that there might well not have been.

My critics was about the high level of abstraction you used. Of course we always had an army composed of building blocks with a center and wings. With melee infantry, light infantry, range weapon infantry and cavalry of different types. And their position on the battlefield did not change that much either in 2000 years from 500 BC until 1500 AD. But on this high level of abstraction nothing changes that much anyways.

You yourself commit, that there was a change in tactics and equipment in the late roman army, which was mainly caused by the different tactics of the enemies. Also looking to the germans. They improved their military capabilities in the first 300 years since Augustus significantly.

I agree, that the change in tactics on the battlefield, grand strategy and equipment has not caused necessarily a change in the organisation of the army. I guess, that the changes in roman society, e.g. looking to the classes and their role and importance in 1st, 3rd and 4th century had much more impact on the armies organisation. Also the separation of civil and military administration or the introduction of the annona militaris based on a barter economy for army supply of the army had its impact.

As mentioned above, this might have led to the situation, that the legion, which was the former core of the combined military and civil administration was now reduced to its pure tactical military role. Even supply and logistics for the army group was not longer part of the legions role. And so it was consecutive, that the legion was stripped down to a unit of about 1000-1200 perhaps 2000 men. Because this size was much more appropriate in the new late roman exercitus. And finally a commander of a legion (praefect) was not ranked very differently than a commander of an auxilia cohort (tribune) anymore.

It was a mix of tactical needs (enemies) and changes in society and economy, which made the former big traditional legion useless and drove the change of the armies organisation. Not just tactical or military needs.