Emperors and usurpers: 180–260
The Empire that Severus inherited was the product of several centuries of territorial expansion, accompanied by a continually evolving administration to deal with the steady accretion of provinces and peoples. The machinery of civilian government and military organisation had been tried and tested, sometimes with success and sometimes with a conspicuous lack of it; but lack of success was not always entirely detrimental. In adverse situations Rome was reasonably ﬂexible and capable of improvisation, adaptation and change. By such a process the Republic had been transformed into the Principate, and in the course of the third century the Empire progressed from the Principate into the Dominate.