Constantine was the son of Constantius, who had served as a Caesar (a junior emperor) of the Western Roman Empire under Maximian before succeeding Maximian as Augustus (senior emperor) in 305. Constantius’ death in 306 sparked a conflict over who would succeed him. Though Constantine had the support of his father’s army, he allowed Severus, his father’s Caesar, to become Augustus.
Maxentius, the son of Maximian, was angered that he was passed over and declared himself Augustus. He defeated the Severus and Galerius, the Augustus of the East, in 306 and 307. In 311, Maxentius declared war on Constantine, the greatest threat to his power.
In the spring of 312, Constantine led his army toward Maxentius in in Rome. After routing Maxentius’ forces in northern Italy, Constantine approached Rome in October.
According to legend, on Oct. 27, the day before the two armies would battle outside of Rome near the Milvian Bridge, Constantine had a vision instructing him to fight in the name of Christ, with his soldiers’ shields bearing the symbol of Christ. The symbol was either a cross or the labarum, an intersection of the chi (X) and rho (P), the letters of Christ.
Christian author Lactantius, writing several years after the battle, described, “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. He did as he had been commanded, and he marked on their shields the letter Χ, with a perpendicular line drawn through it and turned round thus at the top, being the cipher of Christ. Having this sign (ΧР), his troops stood to arms.”
The author Eusebius, a Constantine apologist, also described the event in “Life of Constantine,” which he wrote after Constantine’s death in 337. According to Eusebius, Constantine saw a vision of a cross rather than the letters of Christ.
“He saw with his own eyes the trophy of a cross of light in the heavens, above the sun, and bearing the inscription, In Hoc Signo Vinces ( By this sign, you will conquer). At this sight he himself was struck with amazement, and his whole army also, which followed him on this expedition, and witnessed the miracle,” wrote Eusebius.
The following day, Constantine’s outnumbered forces defeated Maxentius’ forces, which tried to retreat over the Tiber River on a pontoon bridge. In the chaos of the retreat, the bridge collapsed, leaving only the too-narrow Milvian Bridge as a route to escape. Maxentius and many of his men would drown or be trampled to death in the escape. Constantine rode into Rome with the head of Maxentius.
“There, at around the age of twenty-four, Constantine was hailed as emperor, of the western half of the empire,” writes historian Frank E. Smitha. “He was hailed as a man of boldness and a man favored and guided by the gods.”
Commissioned as a free standing work of art within St. Peter‘s itself, the sculpture The Vision of Constantine was finally unveiled in 1670 as an integral part of the Scala Regia – Bernini‘s redesigned stairway between St. Peter’s Basilica and the Vatican Palace. Unlike other large works by Bernini, art historians have suggested that this work was almost entirely undertaken by him – no other sculptors have been recorded as receiving payment. Bernini’s overall fee was 7,000 Roman scudi.
When Bernini began the work in 1654, quite possibly commissioned by Pope Innocent X, the original plan was to place the sculpture within St Peter’s Basilica. However, when Alexander VII assumed the papal throne a year later, the project was reinvigorated, securing the arrival of a large block of marble which Bernini could use to put existing drawings and sketches into practice. However, for reasons that are unclear, the project was delayed again, and Bernini did not start work on the block until 1662.