During his arduous military campaign to wrest control of Rome from the tyrannical usurper Maxentius six years after his acclamation as the northwestern emperor, Constantine felt the need for supernatural assistance to overcome the substantial armed forces and the superstitious religious rites being used by his enemy. Nothing that the previous generation of emperors who had venerated the pagan deities and persecuted the Christian Church had come to unhappy ends, Constantine raised his eyes to the sky and invoked the "Highest God" of the universe in prayer for assistance in his time of trial. he later confided to Bishop Eusebius of Caesarea what followed, and wore on oath that his story was true. He reported that just after midday "he saw with his own eyes in the heavens a trophy of the cross arising from the list of the sun with the message "Conquer by This'" (Hoc Signo Victor Eris in the Latin account of the emperor, but Τουτω Νικα in the Greek version of the bishop). Constantine did not fully comprehend the meaning of this vision; but that night he had a dream in which Christ appeared to him and admonished him to use a sacred symbol of the Christian faith as a defensive talisman for his army. As Constantine had been a protector of Christian believers in his domains, there were Christian clergymen traveling with his forces and praying for the success of his campaign. He questioned them on the import of his revelations and on the sacred signs of their religion. They responded that the cross was the symbol of the victory over death won through the passion of Christ. They probably also informed him that Christians were marked with the sign of the cross at baptism, and were instructed to invoke the name of Christ when they felt endangered by demonic forces. The emperor therefore learned that the crux et nomen Christi were potent apotropaic devices which could be deployed against the forces of evil. Constantine probably remembered the famous incident during a religious rite at Antioch a dozen years earlier when the failure of a haruspex to find any signs in a sacrificial lamb had been blamed on the hexing of the sacrifice by a Christian palace worker making his forehead with the symbol of the cross. He certainly also recalled that the pagan emperors who had used all the powers of their offices to destroy Christianity thereafter had been struck down through terrible deaths over the past decade - Diocletian, for example, by insanity, and Galerious by penile cancer. The emperor must have reasoned that if Christian signs were more potent than pagan rites and that if the pagan persecutors were not able to destroy the Christian cult, then the Christian Deity would seem to be the Deus Summus, and the sacred symbols of Christ would be able to overcome the superstitiosa maleficia being used against him by Maxentius. At this moment, Constantine committed himself to the Christian God.