Though not a theological controversy, the Edict of Milan was a significant change in the history of Christianity. Emperor Constantine had a vision in which he received instruction to mark his army’s shields with the Greek letters chi and rho. These were the first to letters of Christ. Constantine defeated his enemy, Maxentius, for total control of the Western half of the Roman Empire. This took plan on the Milan Bridge. Constantine then went into Milan and made a peace treaty with the emperor Licinius, which included the ceasing of Christian persecution and the return of property such as buildings and cemeteries. This is referred to as the Edict of Milan, in AD 313. Christianity received a boost of support and was able to once again be spread abroad.