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What Did Constantine Know & When Did He See It?
by Peter J. Leithart
In the public reception area of the Vatican palace are four Stanze di Raffaello, each of which is decorated with paintings from the school of the Renaissance master Raphael. The largest is the Sala di Constantino, the hall of Constantine, and its frescoes depict episodes from the life and legends of Constantine—the Battle of the Milvian Bridge, the Donation of the Vatican Hill to Pope Sylvester (who looks suspiciously like Raphael’s patron Pope Julius II), and the Vision of the Cross.
Flanked by paintings of two popes, the Vision (painted in 1520–1524) shows a startled Constantine in Roman armor standing on a pedestal in front of his commander’s tent. He is beginning to address the mustered troops, but something has interrupted him. His hands rise in surprise as he stares with wide eyes toward the sky.
In the light that breaks through the turbulent dark clouds, three angels hold a cross, and the beams of light shining toward distant Rome double as a banner bearing the inscription EN TOYTO NIKA—“in this sign conquer.” A dragon twists through the sky, writhing in anger but also in abject defeat.
In the seventeenth century, Peter Paul Rubens’s painting of Constantine’s conversion used the same imagery—light from heaven beaming onto an armored Constantine and his troops.
The scene is linked to an undeniable historical event. On October 28, A.D. 312, the army of Constantine clashed with the army of Maxentius near the Milvian Bridge outside Rome. At the time, Constantine was emperor in Gaul and Britain, and Maxentius had claimed Rome and Italy. During 312, Constantine had marched through Italy toward Rome to overthrow a man he considered a tyrant.
Constantine’s army defeated Maxentius when a pontoon bridge collapsed under Maxentius’s fleeing soldiers. Maxentius himself drowned in the Tiber, and his body was found downstream from the bridge. The next day, Constantine entered Rome, accompanied by a soldier bearing Maxentius’s head on a spear.
If Constantine’s victory over Maxentius is undeniable, its meaning is not. Early on, pagan writers offered their own account of Constantine’s conversion experience. Writing in the late fifth century, Zosimus gives a detailed account of Constantine’s Italian campaign—citing troop strength, strategy, positioning, geography, and other details—but he never mentions Constantine’s vision or his conversion.
He admits that Constantine became a Christian, but dates the event a decade and a half after the battle, and links it to a horrific family and political episode, Constantine’s mysterious execution of his son Crispus and his wife Fausta.
Without following Zosimus, many modern scholars have dismissed the story of the miraculous vision. In the nineteenth century, Jakob Burckhardt insisted that we have to give it up, along with all the other legends of Constantine; and the popular historian James Carroll describes it as a “boy’s adventure story.” Yale historian Ramsay Macmullen found in different versions of the story evidence that, over time, the story was blossoming into legend.
At least since Burckhardt, historians have been inclined to see Constantine’s decision in favor of Christianity as a political decision. Burckhardt believed that Constantine was motivated purely by a desire to expand his power, and that his genius lay in recognizing, long before his contemporaries did, the political potential of the Church.
Parallels with Exodus
Even among Christian writers, different stories circulated. To Eusebius, the bishop of Caesarea and the first church historian, the battle of Milvian Bridge was nothing less than a new Exodus. Just as “once in the days of Moses and the Hebrew nation, who were worshipers of God, Pharaoh’s chariots and his host has he cast into the sea and his chosen chariot-captains are drowned in the Red Sea,” so now in the fourth century, “Maxentius, and the soldiers and guards with him, went down into the depths like stone.” Like Pharaoh and his hosts, Maxentius “sank as lead in the mighty waters.”
Constantine and the Roman Christians delivered by him “obtained victory from God” and thus joined in singing the song of Moses: “Let us sing unto the Lord, for he has been glorified exceedingly: the horse and his rider has he thrown into the sea. He is become my helper and my shield unto salvation.” And again, “Who is like you, O Lord, among the gods? Who is like you, glorious in holiness, marvelous in praises, doing wonders?”
When Maxentius attempted to flee “the divinely aided forces of Constantine” by crossing the river, his bridge became an “engine of destruction, really against himself.”
Like Moses’ battle with Pharaoh, this was a battle of deities: The Christian God “stood by the one to protect him, while the other, godless, proved to be the miserable contriver of these secret devices to his own ruin.”
Eusebius saw in Maxentius’s fall confirmation of the proverbial wisdom of the Old Testament: “He has made a pit, and dug it, and is fallen into the ditch which he made. His mischief shall return upon his own head, and his violence shall come down upon his own pate.”
Israel’s crossing of the sea was, the Apostle Paul said (1 Cor. 10:1–4), a baptism, a transition from Egypt into the wilderness and toward the land of promise. For Eusebius, Rome had been baptized in the Tiber.
Public Vision or Private Dream?
Eusebius also recorded what became the most popular version of the story, the one Raphael used for his painting. Constantine knew that within the city Maxentius, like the Babylonian Belshazzar, was deploying every form of magic and incantation against his rival. Being a religious man, Constantine knew that his army could not stand alone against such a supernatural attack, and he considered what God he might ask for help.
Constantine was already becoming convinced that the policy of persecution was ineffectual, and worse. Even at the height of the persecution, his father had enforced the policy leniently, and Constantine could not but be struck by the contrast between Constantius’s prosperous life and calm death and the frenzied panic of the dying emperor Galerius, the architect of the persecution. The God of the Christians must be a very powerful God, and turning to him was worth the risk.
Almost immediately, his prayers were answered. When Constantine “called on him with earnest prayer and supplications that he would reveal to him who he was, and stretch forth his right hand to help him in his present difficulties,” he received “a most marvelous sign . . . from heaven, the account of which it might have been hard to believe had it been related by any other person.”
According to Eusebius, “about noon, when the day was already beginning to decline, he saw with his own eyes the trophy of a cross of light in the heavens, above the sun, and bearing the inscription, Conquer by this.” His entire army saw it, and all were “struck with amazement” at “the miracle.”
Eusebius vouched for the truth of this account by claiming that he received it straight from Constantine: “But since the victorious emperor himself long afterwards declared it to the writer of this history, when he was honored with his acquaintance and society, and confirmed his statement by an oath, who could hesitate to accredit the relation, especially since the testimony of after-time has established its truth?”
Earlier than Eusebius, though, Lactantius, who as the tutor to Constantine’s sons was closer to the emperor than Eusebius, recorded a simpler story. According to his account, “Constantine was directed in a dream to cause the heavenly sign to be delineated on the shields of his soldiers, and so to proceed to battle.”
Following the directive, he “marked on their shields the letter X, with a perpendicular line drawn through it and turned round thus at the top, being the cipher of Christ. Having this sign, his troops stood to arms.”
The differences between the two accounts are obvious. Eusebius records no dream, and though Lactantius says that Constantine marked his soldiers’ shields with the “heavenly sign,” he does not inform us where Constantine got the idea for the sign. By Lactantius’s account, Constantine’s vision could well have taken place in private, while Eusebius claims that Constantine’s entire army witnessed the sign.
Over the centuries, this has been the “Constantinian question,” and it is still one aspect of the riddle of the fourth century: What, if anything, happened to Constantine on the night before the battle of Milvian Bridge? Did he become a half-committed polytheist? Was he a syncretistic monotheist, trying to split his loyalties between the Christian God and Sol, the god of the sun? Was he a cynical politician ready to jump on whatever horse would carry him forward? Did he have any “subjective religious experience”?
We can be sure of at least this: Something happened. Eusebius claimed to have heard the story directly from Constantine, who confirmed the story with an oath. One might dismiss the oath, but this assumes a high level of cynicism on Constantine’s part that is hard to believe. Credulous Eusebius may have been, but he was not the only one to hear the story.
Coins issued in the middle of the fourth century by Constantine’s sons depict the scene, and besides, Constantine told Eusebius of a public event, witnessed by soldiers, a story, in short, that could be confirmed or denied by men in Constantine’s retinue.
Constantine may have lied and taken a false oath; Eusebius may have lied or distorted what he heard. In the abstract, those are possible, but neither option is plausible. The far more likely conclusion is that Constantine saw something that he took as a divine sign.
Constantine had a history of mystical experience. An anonymous panegyric delivered probably in 310 refers to an earlier vision of Apollo. The orator reminds Caesar Constantine that he did “see your patron Apollo, and Victory accompanying him, offering you a crown of laurel.” Referring either to the god, or perhaps to the “deified” emperor Augustus, he adds,
You did see him, and you recognized yourself in the image of the one to whom the sacred poems of bards prophesied that the kingdoms of the whole world were due by right. That has now come to pass, seeing that you are, Emperor, like him, young, blessed, our savior and a very handsome one!
Mark of Conversion
After 310, Constantine changed his loyalty from the war god Mars to the sun god Sol, who also doubled as Apollo. After 312, he also changed the standards that led his army into battle, and painted Christian insignia on his helmet and shield. These may seem small matters to us, but they were not trivial to fourth-century Romans. Andreas Alfoldi wisely remarks:
The tiniest detail of the imperial dress was the subject of a symbolism that defined rank, that was hallowed by tradition and regulated by precise rules. Anybody who irresponsibly tampered with it would have incurred the severest penalties. Especially would this have been the case if anyone, without imperial authority, had provided the head-gear of the Emperor with a sign of such serious political importance as that attached to the monogram of Christ. Or can one imagine, for example, that the cap of the King of England could be adorned by a chamberlain or a court-painter with a swastika or a sickle and hammer—without the consent of the King?
Though as practical as any successful ruler and military leader, Constantine was also so deeply religious in the fourth-century way that his religion often looks to us like superstition. A superstitious/religious Constantine would be disinclined to insult the gods by changing the standards of his army on the eve of a major battle. Roman army standards were religious objects, venerated by the troops and often credited with talismanic powers, as indeed the labarum eventually was.
To change standards on the eve of a major battle marked a conversion, both political and religious. It announced a change of loyalty from one divine patron to another. Constantine would not have changed the standards without powerful justification, a justification like a direct communication that he believed came from a different god, perhaps even from God.
For the ancients generally, war was no exercise of sheer power, no secular Realpolitik. War involved bloodshed, and bloodshed was always surrounded by ritualized hedges and taboos. Diocletian’s forces constituted a “sacred retinue,” and Constantine would have thought of his army in the same way. Armies won by divine intervention, and the victory of an army was the victory of the army’s god.
If military victory depended upon the patronage of a powerful god, it would be extreme folly to abandon the god at the very moment of engagement.
And it was not only the standard that changed. After 312, Constantine’s propaganda turned, more and more firmly, from paganism toward Christianity. “Propaganda” is the wrong term at the outset. Fourth-century Romans were religious to the point of superstition. It is anachronistic to attribute to any political leader of the time the kind of ironic stance toward religious legitimization that is implied by the word “propaganda.”
Constantine’s iconography sent multiple messages. Portraits associated him with the “good emperors” of the past. In contrast to the grizzled soldier-emperors of the immediate past, Constantine had himself depicted clean-shaven and youthful, like a conquering Alexander or a new Augustus restoring the glories of the early empire. He was Constantine Trachala, Constantine of the Thick Neck, his thick neck a physiognomic sign of his strength and firmness.
Constantine’s father had taken on the name Marcus Flavius Valerius Constantius. By taking this name, Constantius associated himself with the short-lived Flavian dynasty, and Constantine maintained the connection. His full name was Caesar Flavius Valerius Aurelius Constantinus Augustus.
The Flavian title was calculated to endear him to the capital, which was dotted with monuments left by the earlier Flavians—the Temple of Peace, the Arch and Baths of Titus, and, most famously, the Colosseum itself. Constantine’s own arch was later placed in the same area of the city, aligned with the Arch of Titus.
The religious message of Constantine’s propaganda, though, was ambiguous. In 315, the Senate acknowledged Constantine’s victory over Maxentius with an honorific arch, which declared Constantine the liberator urbis and attributed his victory to instinctu divinitatis. The Senate’s language was general enough to appeal to a Christian or a pagan, but it is significant that it did not name Jupiter or Apollo or Mars as the inspiring deity.
Besides, the phrase had a well-known significance in Roman religious thought. Florus’s standard account of the crimes and expulsion of Tarquin the Proud claimed that the Roman people were stirred to resist tyranny by instinctu deorum, and Constantine’s arch proclaimed that the new emperor had been inspired to overthrow another tyrant by the same instinct. Cicero used the similar phrase instinctu divino in a discussion of divination describing an impulse that enables the soul to see the future because of kinship with the gods (deorum cognatione).
After Constantine’s victory in 312, a panegyrist gave a twist to the Ciceronian phrase by complimenting the emperor on his ability to share secrets with illa mente divina, while his enemy was haunted by the Furies (nocturnes pulsus Ultricibus). In other words, the Senate’s inscription acknowledged that Constantine was in intimate contact with some divine power that gave him knowledge of future events. Even the predominantly pagan Senate of 315 recognized that their new emperor was divinely inspired.
Pagan signs continued to appear on Constantine’s coins and other depictions, but he added explicitly Christians symbols like the Chi-Rho and the cross, and these symbols gradually replaced the pagan signs. When he did employ pagan religious symbolism, it was typically monotheistic symbolism associated with Sol/Apollo, but even these were removed from Constantine’s coins between 318 and 321, before he conquered the Eastern empire.
Ambiguity, furthermore, was more than fence-sitting. In a world where earlier emperors had identified themselves unambiguously with Jupiter and where the Western emperors were known as Herculeans, Constantine’s refusal to use such titles and imagery marked a new course. The Senate and panegyrists were not sure what divinity Constantine had contact with, but they knew enough to stay clear of calling him “Jupiter.”
The objective, visual, and tangible evidence is this: Prior to 312, Constantine’s coinage and military standard honored pagan gods, particularly Sol the sun god or Apollo. After 312, he adopted a Christian standard and Christian military insignia, and put Christian symbols on his coins, which gradually replaced pagan signs. Something happened in between.
The argument that Constantine was motivated by political considerations does not make sense. Most citizens of the empire were still pagans in 312, and paganism was still vibrant. Favoring the Church was a risky political move. Politics alone cannot explain Constantine’s open support of a religion that many Romans still regarded with suspicion, and some with hostility.
Is there another explanation? Constantine said he changed because he received a sign from the Christian God. Might that be true?
Two Accounts Reconciled
I believe the answer is yes. Peter Weiss has offered a convincing account of Constantine’s conversion and its aftermath that merges the Eusebian and the Lactantian versions of the story, and illuminates a great deal about Constantine’s entire career.
The two versions refer, Weiss says, to two different incidents. Eusebius described a public vision, witnessed by both Constantine and his men, while the army was marching “somewhere.” Weiss says that this probably occurred in Gaul in 310, two years prior to the battle of Milvian Bridge, at the time when other evidence indicates that Constantine began to devote himself to the invincible sun god, Sol invictus.
In other words, Weiss thinks that the “pagan” vision of Constantine mentioned above was the same as the vision that Eusebius recounts in a Christianized form. That is possible. Whether or not the panegyrist and Eusebius give different interpretations to the same vision, though, the vision Eusebius describes was some time prior to the battle for Rome.
Constantine kept the vision in the back of his mind for some time, pondering what it could mean. On the eve of the crucial battle with Maxentius, he had a dream. When he discussed the dream with some Christians in his entourage, they told him that Christ had appeared and gave him a Christian interpretation of the sign he had witnessed two years before.
Weiss makes a convincing case that the sign that Constantine and his army saw in 310 was not the flying scroll envisaged by Raphael and Rubens, but a sun halo, a circular rainbow formed when ice crystals in the atmosphere refract sunlight. In a sun halo, the sun is at the center of the circle, and it often radiates beams in a cross or asterisk shape inside the circumference (for images, Google “sun halo”). In 310, Weiss concludes,
Constantine, with his army, unexpectedly witnessed a complex halo-phenomenon. He saw a double-ring halo, each ring with three mock suns arranged in cross-formation around the sun, tangent arcs or points of intersection with the circle, presumably with a more or less distinct light-cross in the middle. He saw it in the spring and in the afternoon, which is when the phenomenon mainly occurs.
This vision elucidates much about Constantine’s subsequent career and faith: It explains his recurrent resort to light and sun imagery, his tendency to link Christ with the sun and with the sun god Sol, his sense of divine commission and his confidence of success, his devotion to the cross as a sign of victory and kingship, and the iconography of the sun that appears on Constantine’s constructions and those of his heirs.
To us, Weiss’s explanation might seem to be a purely “naturalistic” explaining away of a miracle. For early Christians, that would not have been the case. Even if a sign in the sky could be thoroughly explained by science, they would still recognize God’s hand in arranging a particular set of phenomena in a particular time and place.
A cross of light in the sky, encircled by a “crown”—for fourth-century Christians, how could that be anything other than a God-given sign of conquest by the Cross? To my mind, twenty-first-century Christians can only agree.
Guided by God
If David Petraeus had recommended a surge in Iraq based on an eclipse or other sign in the heavens, he would have been forced into psychiatric treatment, followed by early retirement.
Constantine, though, was a fourth-century Roman who, like everyone else in his time, believed that the gods guided humanity with signs and portents. He saw something, probably a sun halo that he interpreted as a sign that committing himself to the God of the Christians would give him victory.
In the event, Constantine did win, and gave the glory of his victory to the Christian God. Rome, the West, and the world were never the same again. •
Peter J. Leithart is an ordained minister in the Presbyterian Church in America and teaches theology and literature at New St. Andrews College in Moscow, Idaho. He is the author of Ascent to Love: A Guide to Dante's Divine Comedy and Against Christianity (both from Canon Press). He is a contributing editor of Touchstone.