In the third century CE, as Roman leaders vied with each other for power and constantly fought civil wars, Rome’s famous roads fell into disrepair, the economy was crippled, the continent-wide trade system that had flourished in the previous years was replaced with a basic barter system, and there was a reduction in international trade. People became ever more fearful for their personal safety, and the imperial crisis saw an increasing trend toward sacrificing personal liberties and rights in return for guarantees of safety from wealthy landowners. All of this foreshadowed the emergence of the European feudal system and serfdom.

These were obviously turbulent times, and given the volatility, many historians have debated how the Roman Empire managed to survive in any form at all, let alone remain robust enough to allow Diocletian and his successors to restore it. Given the many people involved and the relatively short era in which everything transpired, Rome’s imperial crisis has been difficult for historians to summarize, which is why, despite being one of the most intriguing periods in Roman history, it is often overlooked by people who have chosen to focus on the more cohesive periods before and after it.

This set the stage for the conflicts that would culminate with the rise of Constantine in the early fourth century, and it would be hard if not outright impossible to overstate the impact he had on the history of Christianity, Rome, and Europe as a whole. Best known as Constantine the Great–the kind of moniker earned only by rulers who have distinguished themselves in battle and conquest–Constantine remains an influential and controversial figure to this day. He achieved enduring fame by being the first Roman emperor to personally convert to Christianity and for his notorious Edict of Milan: the imperial decree that legalized the worship of Christ and promoted religious freedom throughout the empire.

Moreover, even though he is best remembered for his religious reforms and what his (mostly Christian) admirers described as his spiritual enlightenment, Constantine was also an able and effective ruler in his own right. Rising to power in a period of decline and confusion for the Roman Empire, he gave it a new and unexpected lease on life by repelling the repeated invasions of the Germanic tribes on the Northern and Eastern borders of the Roman domains, even going so far as to re-expand the frontier into parts of Trajan’s old conquest of Dacia (modern Romania), which had been abandoned as strategically untenable.

However, it can be argued that despite his military successes–the most notable of which occurred fighting for supremacy against other Romans–Constantine may well have set the stage for the ultimate collapse of the Roman Empire as it had existed up until that point. It was Constantine who first decided that Rome, exposed and vulnerable near the gathering masses of barbarians moving into Germania and Gaul, was a strategically unsafe base for the empire, and thus he expanded the city of New Rome on the Dardanelles Straits creating what eventually became Constantinople. By moving the political, administrative, and military capital of the empire (as well as the imperial court with all its attendant followers) from Rome to the East, Constantine laid the groundwork for the eventual schism that saw the two parts of the Roman Empire become two entirely separate entities, go their own way, and eventually collapse piecemeal under repeated waves of invasion.