 Beginning in the mid @-@ 3rd century the emperors began to favor members of the equestrian order over senators , who had had a monopoly on the most important offices of state . Senators were stripped of the command of legions and most provincial governorships ( as it was felt that they lacked the specialized military upbringing needed in an age of acute defense needs ) , such posts being given to equestrians by Diocletian and his colleagues — following a practice enforced piecemeal by their predecessors . The emperors , however , still needed the talents and the help of the very rich , who were relied on to maintain social order and cohesion by means of a web of powerful influence and contacts at all levels . Exclusion of the old senatorial aristocracy threatened this arrangement . 
