Scala/Art Resource

The din of battle echoes from an elaborate fresco celebrating the triumph of Constantine at the Battle at the Mulvian Bridge in 312A.D. The historian Eusebius reports that before the battle, Constantine had a vision of a cross blazing in the sky. Constantine marked his helmet and shield and those of his troops with a Chi-Rho monogram—a symbol combining the first two Greek letters of the word Christ. When, thus armed, his army vanquished Maxentins, a rival for control of the western half of the Roman Empire, Constantine converted to Christianity.

In 313 Constantine met with Licinius, the emperor of the east, in Milan. The two co-emperors jointly issued the “Edict of Milan,” which decreed freedom of worship throughout the empire. Eleven years later, by defeating Licinius in battle, Constantine secured control of both halves of the Roman Empire and became the first Christian emperor of Rome.

These early 16th-century frescoes by Giulio Romano (see more about Giulio Romano in the sidebar to this article), a student of Raphael’s, decorate the Vatican’s Hall of Constantine. Two great “tapestries” unroll on either side of the seated popes, Clement I, center left, and Sylvester I, center right. The artist achieves the illusion of fabric by depicting each fresco with rolled ends and a fringe on the lower edge, and by giving the upper edge an “embroidered” border and scalloping it so that it appears to be tacked to the wall.

In the fresco on the left, Constantine prepares for battle. Standing before his tent, left arm outstretched, he gazes transfixed at the turbulent clouds that part to reveal a bright vision of a cross supported by angels. A ray of sunlight bursts from the clouds with the Greek words (written in Latin letters) for “By this sign you will conquer.” Although the artist has painted a cross, Constantine probably visualized a Chi-Rho monogram, which was an equally common symbol of Christianity in his day.

The right-hand wall shows the furious battle. Constantine mounted on a rearing white horse just to the left of the river brandishes his spear and looks down on Maxentius, the crowned figure astride the horse foundering in the river. Behind Constantine two battle standards bear a cross atop the imperial Roman eagle.

Eusebius relates that when Maxentius drowned, a bridge of boats floated beside the actual Mulvian Bridge, a portion of which had earlier been removed to blend impede Constantine’s progress. The artist omits this moving bridge but portrays fighting on two boats as well as on the intact stone bridge behind them.

On pedestals flanking the popes and the “tapestries” are personifications of, from the left, Eternity, Moderation, Courtesy, Faith, Religion and Justice.