Who was Constantine and why did he move the capital of the Roman Empire to Constantinople?

Constantine the Great, also known as Constantine I or Saint Constantine (in the Orthodox Church as Saint Constantine the Great, Equal-to-the-Apostles), was a Roman Emperor from 306 to 337 AD. Constantine was the son of Flavius Valerius Constantius, a Roman Army officer, and his consort Helena. His father became Caesar, the deputy emperor in the west, in 293 AD. Constantine was sent east, where he rose through the ranks to become a military tribune under the emperors Diocletian and Galerius. In 305, Constantius was raised to the rank of Augustus, senior western emperor, and Constantine was recalled west to campaign under his father in Britannia (Britain). Acclaimed as emperor by the army at Eboracum (modern-day York) after his father's death in 306 AD, Constantine emerged victorious in a series of civil wars against the emperors Maxentius and Licinius to become sole ruler of both west and east by 324 AD.

As emperor, Constantine enacted many administrative, financial, social, and military reforms to strengthen the empire. The government was restructured and civil and military authority separated. A new gold coin, the solidus, was introduced to combat inflation. It would become the standard for Byzantine and European currencies for more than a thousand years. The first Roman emperor to claim conversion to Christianity, Constantine played an influential role in the proclamation of the Edict of Milan in 313, which decreed tolerance for Christianity in the empire. He called the First Council of Nicaea in 325, at which the Nicene Creed was adopted by Christians. In military matters, the Roman army was reorganised to consist of mobile field units and garrison soldiers capable of countering internal threats and barbarian invasions. Constantine pursued successful campaigns against the tribes on the Roman frontiers-the Franks, the Alamanni, the Goths, and the Sarmatians-even resettling territories abandoned by his predecessors during the Crisis of the Third Century.

The age of Constantine marked a distinct epoch in the history of the Roman Empire. He built a new imperial residence at Byzantium and renamed the city Constantinople after himself (the laudatory epithet of "New Rome" came later, and was never an official title). It would later become the capital of the Empire for over one thousand years; for which reason the later Eastern Empire would come to be known as the Byzantine Empire.

Constantine the great was known as the last romen emperor and the first byzantine empire. he moved the romen capital to constantinople mainly because the western empire collasped and only the eastern part remained. he worked his whole life as emperor to reclaim the lost territory.