The Christian Basilicas of Constantinian RomeThe Ancient World (1995)
"During his arduous military campaign to wrest control of Italy from the usurper Maxentius in A.D. 312, Constantine the Great invoked the Deus summus, the "Highest God" of the universe, for aid and power in his time of trial. Believing that he received an answer to this appeal through revelatory experiences from the God of the Christians, he decided to use the symbols of Christ as talismanic emblems on the arms of his troop. Behind the caelestia signa of his new patron Deity, Constantine defeated the forces of the enemy at the climactic Battle of the Mulvian Bridge on 28 October 312."
Citation InformationCharles M. Odahl. "The Christian Basilicas of Constantinian Rome" The Ancient World Vol. 26 Iss. 1 (1995) p. 3 - 28
Available at: http://works.bepress.com/charles_odahl/68/