Flavius Valerius Aurelius Constantinus (27 February c. 280 – 22 May 337 AD), commonly known as Constantine I, (among Roman Catholics) and Constantine the Great, or Saint Constantine (among Eastern Orthodox and Byzantine Catholic Christians), was an Illyrian Roman Emperor, proclaimed Augustus by his troops in 306, who ruled an ever-growing portion of the Roman Empire until his death. Best known for being the first Christian Roman Emperor, the Edict of Milan - issued by his co-emperor Licinius - helped to put an end to institutionalized persecution of Christians in the Empire.
According to Lactantius, Constantine was visited by a dream the night before the battle, wherein he was advised to use the Equal-Armed Cross on military wear by visions of angels and Jesus. It was not the crucifix. The Equal-Armed Cross was an ancient pagan European symbol of good luck like the Cross pattée, the four-leafed clover of Ireland and the swastika. He won his battle against Maxentius using a pagan good luck symbol and so then converted Rome to Christianity.
The Byzantine liturgical calendar, observed by the Eastern Orthodox Church and Eastern Catholic Churches of Byzantine rite, lists both Constantine and his mother Helena as saints. Although he is not included in the Latin Church's list of saints, which does recognize several other Constantines as saints, he is revered under the title "The Great" for his contributions to Christianity.
In 324, Constantine announced his decision to transform Byzantium into Nova Roma and on May 11, 330, he officially proclaimed the city the new capital of the Roman Empire. The city was renamed Constantinople, The City of Constantine, after Constantine's death in 337. It would remain the capital of the Byzantine Empire for over a thousand years, a reign interrupted only briefly by its 1204 sacking and occupation in the Fourth Crusade, until it finally fell to the Ottoman Empire in 1453.