Flavius Valerius Constantinus - the famous Constantine - was born in Moesia in either 274 or 280 (the date is disputed). His father was Constantius Chlorus, one of the Caesares in Diocletian’s tetrarchy; his mother was Helena, a concubine or wife of his father who was later repudiated. The army acclaimed Constantine imperator upon his father’s death in 306 even though this act violated a rule Diocletian had established in order to avoid dynastic successions, viz. that the adopted Caesares were to assume the higher role of Augusti upon the death of their predecessors, then use adoption to nominate a new Caesar to replace themselves in a sequence that should have ensured a smooth succession of qualified emperors. This precipitated a prolonged civil war between the Augusti and the Caesares that Diocletian alone refused to join, himself having retired into private life in the hope that the system he had devised might prevent precisely this type of military conflict from arising between those aspiring to the purple. In 312 Constantine formed an alliance with Licinius and contributed to the conflict of rivals in the western part of the empire, defeating the troops of Maxentius at the Milvian Bridge; Licinius, meanwhile, conquered the eastern part of the empire, which was subsequently divided between the two Augusti and saw alternating periods of strife and peace. This unstable situation endured for about a decade until Constantine won a decisive victory in 324 and condemned Licinius to death. During a period of close collaboration, the two Augusti issued the so-called Edict of Milan (313), a decree that essentially confirmed earlier legislation guaranteeing freedom of religious practice and extended it to members of the Christian religion; Licinius published it at Nicomedia.
In 325, the same year in which Licinius was killed, Constantine ordered his own son, Crispus, and his own wife, Fausta, to be executed. The following year (326) he moved the capital of the empire from Rome to Byzantium, the location of which was better suited to confronting the constant threat of Germans invading across the Danube; at the same time, he renamed it Constantinople. Ten years later (335), he divided the administration of the empire among his surviving sons Constantine II, Constans, and Constantius, as well as his nephews Dalmatius and Hannibalianus. He died at Nicomedia in 337 while trying to fight against the Sasanian king Shapur II of Persia. He was buried at Constantinople, a city he had hoped would become a new Rome and a new capital for the empire; to this day he is venerated as a saint by the Orthodox Church.
Constantine followed Diocletian’s program of reform by introducing important innovations in the areas of public administration, the organization of the armed forces, and the economy. His most significant contribution to the last of these was the introduction of the solidus, a pure gold coin that granted its possessors - those in the most affluent segments of society - guaranteed buying power. He also inserted himself into the politics of religion: he was a supporter of Christianity, presenting himself as its protector, and was responsible for convening the famous Council of Nicea (325), which attempted to put an end to the internal Church disputes between Arians and the Anti-Arians. Constantine was baptized on his deathbed.
As is the case for many rulers, it is difficult to establish the extent to which texts attributed to Constantine are his own works, were written by his secretaries, or are forgeries composed in later periods. Among those most relevant to the emperor’s literary education, the Oratio ad sanctorum coetum deserves special note. This text, a Greek version of which remains extant, describes an emperor’s intervention in a group of Christians who gather on a Good Friday to discuss whether an acrostic attributed to the Sibyl and a clever reworking of Vergil’s Eclogue 4 should be considered prophecies of the birth of Jesus Christ. Some scholars accept Eusebius’s testimony for the “authenticity” of the Oratio, others consider it Eusebius’s own production, and still others attribute it to a period considerably later, around the middle of the 5th c. Various letters attributed to Constantine also survive - for the most part indirectly - and are now collected online in English translation (http://www.constantinethegreatcoins.com/). One of these purports to address Optatianus Porfirius and discusses his poetic skill, but its authenticity is uncertain. [G. Polara; tr. C. L. Caterine].