Ancient Rome

=== Constantine and Christianity ===
[[Constantine I|Constantine]] assumed the empire as a tetrarch in 306. He conducted many wars against the other tetrarchs. Firstly he defeated [[Maxentius]] in 312. In 313, he issued the [[Edict of Milan]], which granted liberty for Christians to profess their religion.<ref>{{Cite book |last=Gibbon |first=Edward |title=The History of the Decline and Fall of the Roman Empire |date=1906 |publisher=Fred de Fau and Co. |editor-last=Bury |editor-first=J.B. |language=en |chapter=Chapter XX}}</ref> Constantine was converted to Christianity, enforcing the Christian faith. He began the Christianization of the Empire and of Europe—a process concluded by the Catholic Church in the [[Middle Ages]]. He was defeated by the [[Franks]] and the [[Alamanni]] during 306–308. In 324 he defeated another tetrarch, [[Licinius]], and controlled all the empire, as it was before [[Diocletian]]. To celebrate his victories and Christianity's relevance, he rebuilt [[Byzantium]] and renamed it Nova Roma ("New Rome"); but the city soon gained the informal name of [[Constantinople]] ("City of Constantine").<ref>{{Cite book |last=Gibbon |first=Edward |title=The History of the Decline and Fall of the Roman Empire |date=1906 |publisher=Fred de Fau and Co. |editor-last=Bury |editor-first=J.B. |language=en |chapter=Chapter XVII |chapter-url=https://www.gutenberg.org/files/25717/25717-h/25717-h.htm#Blink182HCH0001 |chapter-format=Online version}}; [http://www.roman-emperors.org/conniei.htm Constantine I (306–337 AD)] by Hans A. Pohlsander. De Imperatoribus Romanis. 8 January 2004. Retrieved 20 March 2007.</ref>

The reign of [[Julian the Apostate|Julian]], who under the influence of his adviser [[Mardonius (philosopher)|Mardonius]] attempted to restore [[Religion in ancient Rome|Classical Roman]] and [[Hellenistic religion]], only briefly interrupted the succession of Christian emperors. Constantinople served as a new capital for the Empire. In fact, Rome had lost its central importance since the Crisis of the Third Century—[[Mediolanum]] was the western capital from 286 to 330, until the reign of [[Honorius (emperor)|Honorius]], when [[Ravenna]] was made capital, in the 5th century.<ref>[http://www.roman-emperors.org/honorius.htm Honorius (395–423 AD)] by Ralph W. Mathisen. De Imperatoribus Romanis. 2 June 1999. Retrieved 21 March 2007.</ref> Constantine's administrative and monetary reforms, that reunited the Empire under one emperor, and rebuilt the city of Byzantium, as Constantinopolis Nova Roma, changed the high period of the [[Classical antiquity|ancient world]].