Constantine and his Franks marched under the Christian standard of the labarum. The new religion confronted the old Gods. Supposedly outnumbered, but fired by their zeal, Constantine's army emerged victorious. He was the sole emperor of the entire Roman Empire.

             Constantine is perhaps best known for being the first Roman Emperor to freely allow Christianity, traditionally presented as a result of an omen - a chi and rho in the sky, with the inscription "By this sign shalt thou conquer." This occurred before his victory in the Battle of Milvian Bridge on October 28, 312, when Constantine is said to have instituted the new standard to be carried into battle, called the labarum. Some scholars, however, have called into question this vision. "There was no vision.The Emperor himself never seems to have spoken of it.even on occasions when he might have been expected to do so.There can be little doubt, on the other hand, that at a certain moment before the battle the Emperor underwent some profound spiritual experience."2.

             Christian historians ever since Lactantius have adhered to the view that Constantine "adopted" Christianity as a kind of replacement for the official Roman paganism. Though the document called the "Donation of Constantine" was proved a forgery (though not until the fifteenth century, when the stories of Constantine's conversion were long-established "facts") it was attributed as documenting the conversion of the Roman Empire to Christianity for centuries. Even Christian skeptics have accepted this formulation, though seeing Constantine's policy as a political one, unifying and strengthening the Empire, rather than a spiritual move. .

             Under Constantine's rule, Christians for the first time were free to compete with pagan Romans of wider culture in the traditional cursus honorum for high government positions. Constantine granted various special privileges, and churches like the Church of the Nativity in Bethlehem and the Church of the Holy Sepulchre in Jerusalem were constructed.