ABSTRACT
This chapter examines the decisive period of collapse, renewal, and transformation that includes the so-called ‘Third-Century Crisis’. This period involved famine, war, plague (possibly brought on by climate change), unrest on the frontiers, usurpation, and frequent assassination. The Romans encountered the Goths in eastern Europe and Decius became the first emperor to fall in battle. In Syria, the Romans were beaten by Shapur I, who captured Dura-Europos and destroyed a Roman army at Barbalissos. Nativist and secessionist regimes appeared in Gaul (the ‘Gallic empire’, under Postumus) and in the east, under the leadership of Palmyra and her leaders Odaenathus, Vaballathus, and Zenobia. Calm was restored by Aurelian but further warfare resulted in the decisive victory of Diocletian. Together with Maximian, Galerius, and Constantius, Diocletian instituted the Tetrarchy, the rule of four. Based at cities on the frontier such as Sirmium, Augusta Treverorum, and Nicomedia, the four leaders proved capable of ending unrest on the frontier, and Galerius won a solid victory over the Sasanian king Narseh in 298, which resulted in the Peace of Nisibis, giving Rome a major advantage in the east. Diocletian began financial and administrative reforms that strengthened central government, introducing dioceses, vicars, and prefectures. The role of the praetorian prefect changed during this period, and then again under Constantine, who emerged victorious in the civil war that followed the abdication of Diocletian and Maximian in 305. Constantine’s adoption of Christianity further strengthened imperial unity and central government as the emperor took an active role in determining orthodoxy vs. heresy, and Constantine’s substantial administrative reforms continued what Diocletian had started. Senatorial influence and the importance of Rome declined to the benefit of the equestrians, Tetrarchic capitals, and the new foundation of Constantinople, while an increase in social stratification amongst senators and equestrians, tied to office-holding and new ranks and titles, created a distinctive late Roman aristocracy.
