Tradition tells us that Constantine was converted to Christianity suddenly by a miracle. One day, during the conflict with Maxentius at Milvian Bridge, he and his whole army saw a bright cross in the heavens with this inscription in Greek on it: "In this sign, conquer." In a dream that night Christ appeared to him and commanded him to use the emblem of the cross as his battle ensign, and promised him victory in consequence. Constantine immediately had the costly _labarum_ made to be carried before his army and with it at Milvian Bridge, ten miles from Rome, he vanquished his foe.[117:1] Three theories have been proposed to explain the spectacle of the cross: 1. That it was a genuine miracle, supported by the following facts: (a) Eusebius, who gives us the first account, had all the evidence directly from Constantine himself under oath; (b) Constantine's whole army "witnessed the miracle and put the emblem on their shields"[117:2]; (c) Socrates says the original standard could still be seen in his day.[117:3] The older historians all upheld the miracle, although few scholars to-day take that view.[117:4] 2. That it was a natural phenomenon coloured by Constantine's imagination, or an optical illusion, or a dream.[117:5] 3. That it was a pious fraud, deliberately invented either by Constantine, or by Eusebius.[117:6] Whatever the theories may be, the fact remains that for some reason Constantine invoked the aid of the Christian's God, and carried the Christian emblem in front of his troops to one victory after another until he became sole ruler of the Empire. If it was merely experimenting with the name and cross of Jesus, the experiment brought convincing belief, for the sacred emblem was employed in all later military campaigns. The triumph over Maxentius at Milvian Bridge was a great victory for Christianity. Constantine had a statue of himself with a cross in his hands set up in Rome. An inscription on it stated that through Christianity the glory and freedom of Rome had been restored.[118:1] Henceforth Constantine extended imperial aid and protection to the Christians and a new era was opened in the history of the Christian Church. He endowed and enlarged Christian churches in Rome and later elsewhere[118:2]; he wrote letters in behalf of Christians in Africa[118:3]; he made Christian bishops, like Hosius, Lactantius, and Eusebius, his trusted political advisers; and he enacted laws legalising the new faith and protecting its adherents.