Now that no region of the empire was safe from attack, something different was needed. Which had to undertake much of the execution of government policy, and it made coordination of military and civil policy slow and difficult.
But it was cumbersome, it depended on the cooperation of the governing bodies of cities, It was a system designed to keep generals from dabbling in politics and staging military coups, and it worked. Army commanders had none over the civilian population. Civilian governors of provinces had no authority over troops stationed in their area. Since the days of Diocletian and Constantine, at the turn of the third and fourth centuries, rigid separation of civil and military authority had been the rule.
