For its first two centuries the Roman Empire enjoyed a relatively peaceful existence. There were short periods of trouble and instability, but they had no lasting effect. At the end of the second century AD, the situation began to change and by the third century the Empire was beset by serious internal and external threats. _Rome in the Third Century_ examines this time of troubles. Michael Sage begins by analysing the available sources, which are difficult to use and provide mostly fragmentary glimpses of the period and looks at the surprising disappearance of historical writing in the western half of the empire. He then discusses in detail the increasing pressures on Rome’s northern and eastern frontiers, along with the growing internal threats that the empire faced as the state weakened and experienced increasing internal disintegration. He then narrates the period between the death of the emperor Septimius Severus in 211 and the accession of the emperor Diocletian at the end of the century, when a reformed empire emerged, in many respects very different from its predecessor. The crucial changes in government and the military of this period are explained and assessed and there is a new analysis of contemporary views, both Christian and pagan, of the crisis.