High Imperial Roman army vs Late Roman army

[Alexand96]

To enter the fray here, I'd posit that weapons and body armor would have much less impact on any such engagement than others seem to think. In fact, we don't even know if the Roman armies would look all that different in some respects, from Republic, to Principate/Empire and into to Late Rome, if you're just focusing on the individual legionary. Basically the same configuration of kit: helmet, sword, shield, spear or pila, ring mail being the prominent form of body armor throughout the entire Roman period. You get the idea.

I think deciding factors would be, ceteris paribus, the relative distribution of cavalry and their tactical effectiveness in the Late Roman contingent vs. the effectiveness of the earlier Romans in countering said horse in close infantry formations. If the Late Romans can’t utilize their horse to break the earlier Romans’ lines, then they will eventually lose the conflict as their infantry positions are overrun (by the numerically superior early-Roman infantry) while their cavalry contingent (intelligently) flees the battlefield. In essence what I am saying is that it would be more of a contest of strategy, tactics, discipline and willpower from the general on down much more than it would be an exhibition of technological superiority/inferiority. By the Late Roman period, the “game had changed,” so-to-speak, out of necessity. The earlier Romans were just playing a different game, not inherently inferior in any military sense - just different. I simply do not see the technological or strategic divide being so great between these two types of forces to say that it would be a route by either side. I think that is naïve thinking on our part, biased by a sense of chronology and “progress.”