The year is 305 and Emperor Diocletian abdicated his position. It is the year of the beginning of the struggle for supremacy over the eastern and western parts of the Roman Empire. A large number of participants were in that fight for supremacy, however, Constantine I the Great emerged as the winner. His reign brought a great change in the political and social life of the time. He was the first emperor to declare himself a Christian, thus triggering a chain reaction that paved the way for Christianity. In addition to publicly recognizing himself as a Christian, Emperor Constantine I the Great led an intense religious policy, all to accept Christianity as a religion. He first declared Christianity a permissible religion and in 313 gave the freedom for everyone to believe in what he considered to be right with the Edict of Milan. He thereby initiated the rapid spread of Christianity, which until then had been hidden in the shadow of persecution and prohibitions. He extended his religious policy to influence the church, which slowly became stronger. He actively participated in solving the problem of unity in the Christian world, because very soon after the edict it became clear to Constantine that it does not actually exist. He was surrounded by very able assistants, among whom stands out Eusebius of Caesarea, who allegedly baptized him on his deathbed. In addition to being a great supporter of Christianity, Constantine proved to be a very capable military leader who had military power in his hands during his reign. His successes in the military field improved the security of the empire, and his intense connection with the church brought him a secure social policy. Constantine the Great ruled successfully for three decades, dying in 337 in his imperial palace in Nicomedia. He is buried in the Basilica of the Holy Apostles, which he had built in Constantinople, which he founded.