||This thesis undertakes a comparative analysis of the Roman Empire during the third-century 'crisis' (AD 249-284) on the one hand and the tetrarchic era (AD 284-324) on the other hand. As an analysis of the Roman Empire in all its aspects is obviously not feasible, the thesis limits itself to the three most important ones: first, Rome's wars against its external enemies; second, the internal instability that plagued the empire throughout this period; third, the empire's economic difficulties. After a short narrative chapter which serves to give a general chronological outline and introduce the key players, each of the three aspects is thouroughly discussed in its own thematic chapter. An important theme of the thesis is comparative historiography, which shows how there remains general agreement among historians that the tetrarchic era represents a significant improvement in the fortunes of the empire compared to the 'crisis' that preceded it. The thesis argues that, contrary to the general consensus, the tetrarchy only improved on the 'crisis' in some regards, while it did no better, and arguably even worse, on other points.