Constantine the Great

Flavius Valerius Constantinus (b. on a 27 February between 270 and 288 in Naissus, Moesia Prima; † 22 May 337 in Anchyrona, a suburb of Nicomedia), known as Constantine the Great (ancient Greek Κωνσταντῖνος ὁ Μέγας) or Constantine I. , was Roman emperor from 306 to 337. From 324 he ruled as autocrat.

Constantine's rise to power occurred as part of the dissolution of the Roman tetrarchy ("rule by four") established by Emperor Diocletian. In 306, Constantine succeeded his father Constantius I after his father's soldiers proclaimed him emperor. By 312 Constantine had prevailed in the West, and by 324 in the Empire as a whole. His reign was particularly momentous because of the Constantinian Revolution, which began the rise of Christianity as the most important religion in the Imperium Romanum. Since 313, the Milan Agreement guaranteed religious freedom throughout the empire, thus also permitting Christianity, which had been persecuted only a few years earlier. Subsequently, Constantine privileged Christianity. In 325, he convened the First Council of Nicaea to settle internal Christian disputes (Arian controversy). Domestically, Constantine pushed forward several reforms that shaped the empire during the rest of late antiquity. In foreign policy, he succeeded in securing and stabilizing the borders.

After 324, Constantine moved his residence to the east of the empire, to the city of Constantinople ("Constantine's City"), named after him. Many details of his policies remain controversial to this day, especially issues concerning his relationship with Christianity.

The Roman Empire at the time of Constantine

The Imperium Romanum had entered a period of crisis in the 3rd century (Imperial Crisis of the 3rd century), in which internal political instability and pressure on the borders increased. Along the Rhine and the Danube, various Germanic tribes or new gentile large-scale groups such as the Franks, the Alamanni and the Goths caused unrest. On several occasions, groups of "barbarians" advanced into Roman territory and plundered Roman towns, which had previously been largely spared attacks for almost two centuries. In the east, the Sāsānid Empire had emerged in 224/226 and became Rome's most dangerous rival (see Roman-Persian Wars). Within the empire, numerous usurpers and attempted usurpations relied primarily on the large army units that now legitimized imperial power (soldier-emperors), so that endless civil wars shook the empire. Although not all spheres of life and provinces were hard hit by the crisis and it was by no means uninterrupted, it proved to be a severe test of endurance for the empire.

Emperors such as Aurelian therefore introduced reforms from the 270s onwards, but it was not until Diocletian came to power in 284 that the empire was placed on a new foundation. He carried out far-reaching reforms and fundamentally reshaped the empire. Among other things, Diocletian introduced a new tax system (Capitatio-Iugatio) and reorganized the army by dividing it into Comitatenses as a mobile field army and Limitanei as border troops. The crisis was finally overcome, and the empire entered late antiquity. In response to the simultaneous military strains on the various frontiers and the constant usurpations of ambitious generals, a multi-emperorship was introduced, the tetrarchy, in which Diocletian functioned as senior Augustus with three co-emperors subordinate to him. This system was based on appointment of successors rather than dynastic succession and served primarily to prevent usurpations. In Diocletian's last years of rule there was a persecution of Christians. In 305 Diocletian voluntarily resigned and forced his co-emperor Maximian to follow suit, so that the previous sub-emperors Constantius I (replacing Maximian in the west) and Galerius (replacing Diocletian in the east) now succeeded him as senior emperors (Augusti). Nevertheless, contrary to Diocletian's intention, the dynastic principle soon reasserted itself (see Dissolution of the Roman Tetrarchy). A bloody civil war broke out for years, at the end of which Constantine was the sole ruler of the empire.