The conversion to christianity of which roman emperor ushered in a time of tolerance, acceptance and eventual dorminance of christianity?

The conversion to Christian of Constantinople the Great ushered in a time of tolerance, acceptance, and eventual dominance of Christianity. It began the transition of the Roman Empire to Christianity and became the dominant religion in the Roman Empire. The shift of religion is usually referred to as the Triumph of the Church, Constantinian Shift, and the Peace of the Church.