The main focus is on the period between the accession of Diocletian in 284 and the death of Constantius II in 361. This period was dominated by those two emperors and Constantine the Great, but they rarely ruled alone - Diocletian created the Tetrarchy - a system with two senior and two junior rulers, and there were fourteen acknowledged Augusti during this period.
I like the format of this book. Instead of diving straight into the narrative, we begin with a lengthy series of thematic chapters, looking at the Roman Empire, its army and its neighbours. The author then moves on to the Third Century Crisis, a near-disastrous period which threatened the existence of the Empire, before a series of capable Emperors restored the frontiers and stability. After that we move onto a narrative military history of the period, covering external wars, civil wars, revolts as well as some of the other wars fought by Rome's enemies (other threats to Persian played a major role in events on the Roman-Persian border for instance).
The author is fairly opinionated, and prevents alternative views of events on several occasions. These are always backed by his evidence, so even if they aren't all convincing, the reader is able to make their own mind up. These cover areas such as the internal organisation of Rome's enemies, the events of some campaigns or the motives of some of the key leaders and writers, but because the author makes it clear when these are his opinion it adds colour without running the risk of misleading.
He is also perhaps a little too willing to believe ancient claims of poisoning, a fairly standard reaction to the unexpected death of any leader - Constantius II died fairly early, during a civil war against his pagan rival Julian, probably of natural causes (a fever), and there is no need to imagine a detailed plot to kill him.
This book makes it clear that the Roman's worst enemy during this period was themselves. The biggest fault in the Imperial system set up by Augustus was the succession. This first became clear after the death of Nero in 68 AD, which ended the Julio-Claudian Dynasty and triggered a brief civil war known as the Year of the Four Emperors. This was only the first of dozens of civil wars and attempted usurpations. All of the main rulers in this period had to fight at least one civil war - Constantine famously decided to support Christianity just before the decisive battle in his rise to power, while Constantius II fought off one usurper and died while marching to defeat another. The adoption of Christianity also helped destabilise the Empire, first by attempting to suppress the long-established Roman religions, creating a Pagan faction that came to power at the end of this period, and second through internal doctrinal disputes between the followers of the Nicene Creed, the Arians and other sects, which led to disputes between different parts of the Roman Empire and between Rome and her Christian allies.
This is a valuable overview of a period in which the Roman Empire was clearly still militarily powerful and resilient, capable of overcoming a series of internal threats and external enemies, and restoring her borders after the sort of Barbarian invasions that in the next century would see the fall of the Western Empire. I'm looking forward to volume two.
1 - The Early Third Century Roman Empire
2 - Enemies and Allies
3 - The Third Century Crisis
4 - The Rebirth of Rome: the Tetrarchy
5 - The Age of Constantine the Great
6 - The Sons of Constantine
Author: Ilkka Syvänne
Publisher: Pen & Sword Military