According to the message of Eusebius of Caesarea before the Battle of the Mulvian Bridge (October 28, 312 CE) Constantine the Great he had a vision that allowed him to win.
Around noon he was to see a luminous cross in the sky, and under it the inscription in Greek – “in this, conquer”. Better known in Latin translation In hoc signo vinces – “In this sign thou shalt conquer”. The next night in a dream, Christ commanded him to use the sign of the cross against his enemies. Eusebius then describes a labarum (legionary banner) with the sign Chi Rho. Constantine was the first emperor to convert to Christianity.
He ended the policy of persecuting Christians and in 313 CE issued Edict of Milan, proclaiming the freedom to profess this religion.
