Quote:The roman military machine that had built the empire had already more or less been subsumed by less professional forces of the civil war 50 years before Constantine,
One of those "forces" was Constantine himself who used a frontier army to march to march on Rome and make himself emperor. That political problem is what he was trying to solve and in doing so, as one commentator put it: Constantine reforms had set the stage for 'lords' on horseback commanding poorly equipped conscripts.
Even worse was that his intention was to cement his dynasty but his sons turned out to be useless sacks of shit. Within 15 years the "dynasty" was overthrown and Rome continued its inexorable decline.