 No further constitutional reforms were enacted during the Principate . The only development of any significance was the continuing slide towards monarchy , as the constitutional distinctions that had been set up by Augustus lost whatever meaning that they still had . Starting in 235 , with the reign of the barbarian Emperor Maximinus Thrax , the Empire was put through a period of severe military , civil , and economic stress . The crisis arguably reached it height during the reign of Gallienus , from 260 to 268 . The crisis ended with the accession of Diocletian in 284 , and the abolishment of the Principate . 
