Constantine the Great was born at Nassius, Yugoslavia around 285, the son of Flavius Valerius Constantius, an army officer, and Helena, his wife. In 293, his father Constantius was raised to the rank of Caesar by the emperor Diocletian, and Constantine himself was sent to Diocletian's court for his education. This was the period of the Tetrachy, with two Augusti ruling in the eastern and western halves of the Roman Empire, and with two Caesars, junior emperors, under them. In 305, the two emperors Diocletian and Maximianus abdicated by previous arrangement, to be succeeded by the two Caesars Constantius and Galerius. Two new Caesars were appointed under them, but Constantine was passed over. He went to join his father in Britain, and when the latter died in 306, the troops proclaimed Constantine Augustus in his father's place, thus angering the other rulers. Many years of turbulence and civil war followed, with Constantine eventually vanquishing his rivals in the political arena. With the defeat of Licinius in 324, Constantine became the sole ruler of the roman world, which he remained until his death in 337. From the start, Constantine’s career was linked to the rise of Christianity as a political force. At the battle of the Milvian Bridge, fought against his rival Maxentius in 312, Constantine is said to have seen a vision of Christian symbols in the sky, which promised him victory. Shortly thereafter, he and Licinius issued the edict of Milan, which granted official tolerance to Christianity as a religion, after a long period of persecution. It is unclear whether Constantine was himself a convert, but throughout his reign Christianity was given an increasingly important role in the government of the empire and it became the official religion of the state. In 330, Constantine founded a new capital, a "second Rome" on the shore of the Bosphorus, Constantinople, which eventually eclipsed Rome as the pre-eminent city of the Christian world. This action also confirmed that Constantine was anticipating a new era, with a reorganized social and political structure. He died in his new city after supposedly being baptized on his deathbed.