"Naturally, the actual result of the tetrarchy was protracted civil war; but out of this came Christianity’s big break. In the autumn of AD 312, as Constantine was preparing to fight his rival emperor Maxentius at the Milvian Bridge over the river Tiber, he looked to the heavens and saw a blazing cross above the sun, accompanied by the Greek words “in this sign, conquer” (ἐν τούτῳ νίκα). He took this to be a message from the god of the Christians: clearly a god more who at that moment appeared to be more interested in battles and politics than in his son Jesus Christ’s programme of charity, forgiveness and reconciliation. In any case, Constantine routed his enemies: Maxentius drowned in the Tiber and was posthumously decapitated. Constantine was now on his way to abolishing the tetrarchy and establishing himself as a single emperor to rule over all. From that moment onwards he heaped all the fruits of imperial patronage on Christian bishops and believers. His soldiers went into battle with the Chi-Rho daubed on their shields. Officials from across the empire were told to enforce a new imperial edict issued in Milan in AD 313, which promised non-discrimination against Christians. In Rome, building works began on what would become St. John Lateran and St. Peter’s. In Jerusalem, the first Church of the Holy Sepulchre was commissioned, to mark the spot where Christ had been crucified and entombed. (Later rumour, which assumed enormous significance during the Middle Ages, had it that Constantine’s mother Helena had found the timber of Christ’s cross during a visit in AD 327.) And in AD 330, Constantine formally founded Constantinople, a new imperial capital in the east at Byznatium (Byzantion, now Istanbul) and filled it with monumental Christian churches."