An outline, era by era

Crisis of the Third Century; Constantine; division into East and West

Classical Antiquity · ~500 BCE – ~500 CE

The Crisis of the Third Century is the name given to about fifty years, from 235 to 284 CE, when the Roman Empire nearly broke apart. Dozens of emperors and usurpers rose and fell, most of them killed by their own soldiers. Persian armies in the east and Germanic peoples along the Rhine and Danube raided deep into Roman land. Between 260 and 274 the empire split into three rival states, and the coinage lost much of its silver. Historians still debate how deep the crisis went in different regions.

Diocletian ended the crisis by reorganising the state and sharing power with colleagues, a system called the Tetrarchy. After its collapse, Constantine reunited the empire under one ruler, supported Christianity, and founded a new capital at Constantinople in 330. After his death in 337 the empire was often ruled by several emperors at once. The permanent division into an eastern and a western half came in 395, when Theodosius I died and left the two halves to his sons. The East lasted as the Byzantine Empire for another thousand years.

Things happened, and the rest is history

  1. Twenty years of soldier emperors

    Event

    What happened

    In 235 CE the soldiers murder the emperor Severus Alexander near Mainz, ending the Severan dynasty. In the following decades more than twenty men are acclaimed emperor by armies, and most are killed within a few years. In 251 Decius dies fighting the Goths, and in 260 the Persian king Shapur I captures the emperor Valerian.

    The rest is history

    Valerian's capture was a humiliation without parallel, and his son Gallienus was left to hold a broken empire. Gallienus excluded senators from top army commands and relied on professional soldiers, many from the Balkans. Such men, including Claudius II, Aurelian and Probus, drove back invaders over the following years. The crisis is conventionally said to end in 284, when Diocletian becomes emperor.

    Sources

    1. PrimaryRes Gestae Divi Saporis. Trilingual inscription of Shapur I at Naqsh-e Rostam, c. 260 CE.Shapur's own account of defeating and capturing Valerian.
    2. PrimaryZosimus. New History, Book 1. Greek history, c. 500 CE.
    3. BookPotter, David S. The Roman Empire at Bay, AD 180-395. London: Routledge, 2004.

  2. The empire splits in three

    Event

    What happened

    After Valerian's capture in 260, the general Postumus makes himself ruler of Gaul, Britain and for a time Spain. In the east, Palmyra under Odaenathus and then his widow Zenobia takes control of the eastern provinces. Aurelian defeats Zenobia in 272 and the Gallic Empire in 274.

    The rest is history

    Aurelian thus restored a single empire in about five years. He also built a great wall around Rome, a sign of how unsafe the Italian heartland now seemed. The episode showed that regions could manage their own defence when the central government could not, which shaped later arrangements of shared rule. Aurelian was murdered by his own officers in 275.

    Sources

    1. PrimaryHistoria Augusta, Life of Aurelian. Latin imperial biographies, late 4th century CE.Unreliable in many details and best used with caution.
    2. BookWatson, Alaric. Aurelian and the Third Century. London: Routledge, 1999.

  3. Diocletian and the Tetrarchy

    Event

    What happened

    Diocletian becomes emperor in 284 and in 286 appoints Maximian as co-emperor in the West. In 293 each emperor takes a junior colleague, Caesar, creating a rule of four. Diocletian also splits provinces into smaller ones, reforms taxes and issues an edict on maximum prices in 301.

    The rest is history

    The Tetrarchy brought more stable government and put an emperor close to each frontier. It did not settle succession. Diocletian and Maximian retired in 305, and within a year their arrangement fell into civil war. Diocletian's reorganisation of the provinces and army shaped the late empire, and he lived in retirement at Split until about 311 to 316.

    Sources

    1. PrimaryEdict on Maximum Prices. Latin inscription of Diocletian, 301 CE, copies found across the eastern provinces.
    2. BookCorcoran, Simon. The Empire of the Tetrarchs: Imperial Pronouncements and Government, AD 284-324. Oxford: Clarendon Press, 1996.

  4. Constantine wins the empire

    Event

    What happened

    Constantine is acclaimed emperor by the army at York in 306, after his father Constantius dies. In 312 he defeats his rival Maxentius at the Milvian Bridge near Rome. In 313 he and Licinius agree toleration for Christians, and in 324 Constantine defeats Licinius and rules alone.

    The rest is history

    Constantine ended the Tetrarchy and ruled the whole empire until 337. He favoured the Christian church, funded churches and in 325 presided over the Council of Nicaea, which dealt with the dispute over Arius. He kept strong field armies and a new gold coin, the solidus. His sons split the empire among them after his death. Whether his own conversion was sincere is debated, and he was baptised only shortly before dying.

    Sources

    1. PrimaryEusebius of Caesarea. Life of Constantine. Greek biography, c. 340 CE.
    2. BookBarnes, Timothy D. Constantine and Eusebius. Cambridge, MA: Harvard University Press, 1981.

  5. Constantinople and the division of 395

    Event

    What happened

    Constantine dedicates Constantinople, on the site of the Greek city Byzantium, on 11 May 330. The empire is repeatedly shared between several emperors after 337. Theodosius I rules it alone in 394 and 395, and dies in January 395, leaving Arcadius in the East and Honorius in the West.

    The rest is history

    Contemporaries did not regard 395 as a permanent split, since laws were still issued in both emperors' names. In practice the two courts drifted apart and often disagreed. The Western half lost its emperors in 476, while the East continued until the fall of Constantinople to the Ottomans in 1453. The next entry covers the fall of the West.

    Sources

    1. PrimaryChronicon Paschale. Greek chronicle, 7th century CE, with the foundation of Constantinople in 330.
    2. BookCameron, Averil. The Later Roman Empire, AD 284-430. London: Fontana, 1993.

  6. Constantine's vision of the cross

    Heroic tale

    The legend

    Before the battle of the Milvian Bridge, Constantine sees a cross of light in the sky with the words 'by this, conquer'. In a dream Christ tells him to put the sign on his soldiers' shields. He does, and wins.

    The rest is history

    The story comes in two forms. Lactantius, writing around 314, mentions only a dream before the battle and a sign painted on shields. Eusebius, writing after Constantine's death, says the emperor told him of a vision in the sky under oath. The accounts differ, and the sign may have been the Chi-Rho. Some scholars suggest a solar halo. Constantine's triumphal arch in Rome, dedicated in 315, refers vaguely to divine inspiration, without naming Christ.

    Sources

    1. PrimaryLactantius. On the Deaths of the Persecutors, chapter 44. Latin treatise, c. 314 CE.
    2. PrimaryEusebius of Caesarea. Life of Constantine, Book 1, chapters 28 to 31. Greek biography, c. 340 CE.
    3. BookDrake, H. A. Constantine and the Bishops: The Politics of Intolerance. Baltimore: Johns Hopkins University Press, 2000.

  7. The Donation of Constantine

    Folk tale

    The legend

    Constantine, cured of leprosy by Pope Sylvester, gives the pope authority over Rome, Italy and the entire West. He then moves east to leave the Pope as ruler.

    The rest is history

    This story comes from a Latin document, the Donation of Constantine, probably written in the 8th or 9th century. It was used by popes to support claims to power in the West. In 1440 Lorenzo Valla showed from its language and anachronisms that it could not date from Constantine's time. The real reasons for founding Constantinople were military and political, and Constantine never ruled from Rome for long.

    Sources

    1. PrimaryConstitutum Constantini (Donation of Constantine). Latin forgery, probably 8th or 9th century CE.
    2. PrimaryValla, Lorenzo. On the Donation of Constantine. Latin treatise, 1440.
    3. BookFried, Johannes. The Donation of Constantine and Constitutum Constantini. Berlin: De Gruyter, 2007.

  8. The Council of Nicaea decided the Bible

    Popular belief

    The legend

    At the Council of Nicaea in 325, Constantine and the bishops vote on which books belong in the Bible and decide that Jesus is divine. Books that did not make the cut were banned.

    The rest is history

    Nicaea did not choose the biblical canon. The surviving records deal with the Arian dispute, the date of Easter and church discipline, and produced the Nicene Creed. The New Testament canon developed gradually. Athanasius listed the 27 books now used in an Easter letter of 367, and regional councils later confirmed lists. Constantine did preside over the council and influenced it, but the bishops debated the nature of Christ, not the canon.

    Sources

    1. PrimaryAthanasius of Alexandria. Thirty-Ninth Festal Letter. Greek letter, 367 CE.
    2. BookMetzger, Bruce M. The Canon of the New Testament: Its Origin, Development, and Significance. Oxford: Clarendon Press, 1987.

  9. Constantinople as the 'New Rome'

    Origin story

    The legend

    Constantine is said to have marked out the walls of the new city himself, walking ahead with a spear. When his companions asked how far he would go, he replied that he would go on until the one walking ahead of him stopped.

    The rest is history

    This story comes from the later writer Philostorgius, a Church historian whose work survives only in summary. Constantine did select the site and expanded it far beyond old Byzantium. The city was dedicated in 330 and equipped with a senate, forum, hippodrome and imperial palace. The name 'New Rome' was in use, though its formal status as a second Rome developed over time. By the 5th century, Theodosius II's land walls enclosed an area that held the city for centuries.

    Sources

    1. PrimaryPhilostorgius. Ecclesiastical History, Book 2. Greek church history, early 5th century CE, surviving in epitome by Photius.
    2. BookDagron, Gilbert. Naissance d'une capitale: Constantinople et ses institutions de 330 à 451. Paris: Presses universitaires de France, 1974.

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