Flavius Valerius Constantinus, also known as Constantine the Great, was the first Roman emperor to adopt Christianity. He was educated in the imperial court of Rome and pursued to succeed his father. In 305 A.D., his father became the emperor of the Western Empire. But, when he died in 306 A.D., British troops declared that Constantine should replace his father. The Eastern emperor Galerius refused this claim and gave Constantine a lesser rank.
The Emperor Constantine I was the sole ruler of the Roman world between 324 and 337 A.D. His reign was one of the most crucial of all the emperors in determining the future course of western civilization. By making Christianity the religious foundation of his domain, he set the religious course for the future of Europe which remains in place to this very day. Because he replaced Rome with Constantinople as the center of imperial power, he made it clear that the city of Rome was no longer the center of power and he also set the stage for the Middle Ages. His view of monarchy became the foundation for the concept of the divine right of kings.
Constantine, the son of Constantius Chlorus and Helena, seems to have been born in Naissus in Serbia on 27 February ca. 272 or 273 C.E. When his father had become Caesar in 293 A.D., Constantius had sent his son to the Emperor Galerius as hostage for his own good behavior; Constantine, however, returned to his father in Britain on July 25th, 306. Soon after his father's death, Constantine was raised to the purple by the army.
The period between 306 and 324, during Constantine's rule, was a period of constant civil war. Two sets of campaigns not only guaranteed Constantine a spot in Roman history, but also made him sole ruler of the Roman Empire. On October 28th, 312 he defeated Maxentius at The Battle of the Milvian Bridge. In 314, 316, and 324, he repeatedly defeated his last remaining rival Licinius. Once he had overcome him, he was the undisputed ruler