THE ROMAN EMPEROR CONSTANTINE changed the world. For many millions of people across this planet, an institution that he introduced and promoted has become a central part of their lives; they use or hear words that he approved. In the twenty-first century, Constantine is best known as the Roman emperor who converted to Christianity and in so doing made it possible for Christianity to become a world religion. Without Constantine, Christianity probably would not occupy the place that it does today. Without him it is unlikely that Christianity would have emerged from the mass of conflicting, if often quite similar, belief systems coexisting in the empire into which he was born. Even if there are fewer practicing Christians than there were a couple of generations ago, the immense impact of Christian thought upon the behaviors and thinking of the many generations who came after Constantine makes it very difficult to imagine a world without it. When he was born around AD 282, it would have been far easier to imagine a world in which Christianity had a marginal place.
Constantine’s father Constantius was a member of the Tetrarchy (gang of four) otherwise known as the college of four emperors assembled by the emperor Diocletian, in whose court Constantine spent his late teens and early twenties. Diocletian would remain one of the crucial influences in Constantine’s life. His attitude toward the older man was ambivalent: often he reacted against things he had seen Diocletian do, but almost as often, he adapted Diocletian’s practices for his own purposes; much of his later career was shaped by Diocletian’s strongly held opinion that sons should not succeed their fathers into the “imperial college.”
Diocletian retired as emperor in 305, and Constantius died in office in 306. As the result of a coup launched by Constantine and Constantius’ generals on the day that Constantius died, Constantine became emperor. Initially ruler of just a part of the empire—Britain, France, and Spain—he gradually took over the whole of it through a series of civil wars. The first, in 312, ended with his takeover of Italy and Africa after defeating his brother-in-law, Maxentius, at the battle of the Milvian Bridge on the Tiber outside Rome. It was in the course of this campaign that Constantine became a Christian. At the time that I am writing, the 1700th anniversary of this event is rapidly approaching.
The next round of civil wars ended in 324 when he defeated Licinius (also his brother-in-law), who had once ruled the vast arc of lands running from modern Croatia to Egypt. In the wake of this victory he founded Constantinople, modern Istanbul, on the site of the ancient city of Byzantium. For the next thirteen years with the assistance of a group of experienced officials he ran the whole empire, virtually recreating the collective government of Diocletian.
Constantine lived his entire life within the imperial court, which he saw as the central institution of Roman life. He believed that the emperor’s job was to defend the empire from external foes while creating a more just and ordered society for his subjects; he can often be seen acting on those principles. At the same time, his powerful personality led him to commit acts of violence against those closest to him. A deeply complex man of seemingly boundless energy, Constantine was remembered in later generations not only as the first Christian emperor, but as the emperor who shaped the future course of the Roman world.
In the modern world, Constantine tends to be seen as a somewhat less complex character. Although many people may not be aware of Constantine’s role in creating the Nicene Creed that they might recite on a Sunday morning, or associate him with the words “We believe in One God, the Father Almighty, maker of Heaven and Earth,” those are his words and they do reflect his belief in God. Otherwise we may encounter him in many places throughout Europe and the Middle East. We meet him at the great arch that stands in the heart of modern Rome commemorating his victory over Maxentius at the battle of the Milvian Bridge. So too we can still see churches built on his orders in Rome—San Giovanni on the Lateran and Santa Croce in Gerusalemme—and in its vicinity. In the Pio Clementine Vatican Museum we may view the sarcophagus that was once designed to hold his body (it actually held the body of his mother Helena, in its original location in the mausoleum hard by the modern church of Santi Marcellino e Pietro AD Duas Lauros). In Turkey we might recall that Istanbul was for many centuries Constantinople. If we go to York in England we will see his statue outside the cathedral, which may have been built atop the very building that served as his headquarters on the day he became emperor. Wonderfully displayed in the Cleveland Museum of Art is a magnificent gold pendant that was part of a massive decoration that Constantine probably handed to one of his most senior officials.1 If we visit Trier we can see the remains of the palace that he occupied for a half dozen years before he went to Rome, and in Jerusalem we can still visit the Church of the Holy Sepulcher, on the site of the church he ordered to be built. In many museums we will see the image of Constantine staring at the sign of a cross in the sky, inscribed with the words “In this Sign Conquer.” It is by far the most popular story of how he came to be a Christian, and so it is his Christianity that dominates our picture of the man today.
While our tendency to see the significance of Constantine’s life in terms of his confessional choice is reasonable, this was not always the way Constantine himself would have seen it. For him, the conversion of his empire to Christianity was at first neither a primary goal nor a foreseeable outcome. He approved if his subjects joined him in his faith, but they were far more important to him as subjects. Constantine’s aim was first and foremost to wield more power than anyone else in the world and the exercise of that power was his paramount concern. He understood that power needed to be negotiated, that people needed to be convinced rather than commanded, that they needed to accept his leadership, that they could not be shifted too far from where their moral compass pointed.
The assertions that I make here depend upon a particular reading of the sources for Constantine’s reign, and those sources are sufficiently diverse to allow a variety of interpretations in the centuries that separate his life from ours. In general, these either focus on his religious life or on his administrative habits. All of these sources are to some degree problematic, either because the narrative they offer—when they offer a narrative at all—is highly colored by partisan passion, or because they give us snapshots of the emperor in action that need to be viewed against a complex background: a background that itself must be constructed from documents of many sorts, from works of art, from buildings, from information gleaned about careers that are often incompletely known, and from study of the way people at various levels interacted with each other.
The story that follows falls into eight parts. In the first three I describe the world into which Constantine was born and the influences to which he reacted. In the subsequent sections, I tell his story through the sources as they were written rather than reading backward from the end of his life, seeking to show how he governed and to identify the people with whom he worked most closely. By placing Constantine within the institutions of the Roman state at the time that he was born, and looking at the circumstances that shaped those institutions in the decades before he was born, I hope to reveal a man who did indeed change the world and who did so in ways that may not have been quite those that he intended.