The Decline of the Roman Empire

The Severan Dynasty was the last stable period of imperial reign over the Roman Empire until that of Constantine.

The Dominate Period, when warring generals controlled Rome, was a time marked by insecurity, anxiety, and a rapid succession of emperors.

Emperor Diocletian institutionalized the Tetrarchy, a co-rule that re-established stability in the empire for the period of Diocletian's reign.

Constantine seized sole power over Rome, establishing authority and stability. He then moved the capital from Rome to Constantinople.