Byzantium: Constantine, Constantinople, and the Bulwark Against Islam
The City of Constantine
Constantine resolved to make the city a home fit for an emperor; surrounded it with a wall, cutting off the isthmus from sea to sea; built a palace almost as grand as Rome's; decorated the Hippodrome; incorporated the temple of the Dioscuri in it. (Zosimus, New History, c. 501)
Byzantium–Constantinople–Istanbul identified as one of the most extraordinary natural sites: deep-water harbour, proximity to the sea, and a light quality created by water reflections.
Constantine sought a capital from which land and sea routes between Asia and Europe could be controlled. Chose a site with a safe harbour on the Golden Horn, sealable by a chain to keep out enemy ships and to provide security from the Bosphorus currents.
The Bosphorus is described via mythic Leander–Hero imagery; Maiden’s Tower lighthouse linked to Leander’s swim; modern Istanbul now has two bridges linking Asia and Europe, but passenger ferries still cross the Bosphorus for views of Constantinople.
The city’s geography offered a view of Constantine’s city from deck on a fine day (tea and sesame rings), a popular pleasure in Istanbul.
From Byzantion to New Rome: Constantine’s Rise and the Transformation of Byzantion
Constantine was born in Nisˇ (in the central Balkans); son of Emperor Constantius Chlorus, a key member of the Diocletianic Tetrarchy (284–305), which divided the empire into two halves with two senior emperors and two Caesars.
The Tetrarchy faltered due to rivalry among sons and rivals seeking power; after his father's death at York (306), Constantine was acclaimed emperor by his troops but not recognized by Licinius in the East.
Civil conflict led to three claimants in the West; Constantine defeated rivals south and then Maxentius at the Milvian Bridge outside Rome in 312.
Constantine reportedly saw a vision of the Cross in the sky before Milvian Bridge; interpreted as a sign from the Christian God promising victory.
Following victory, Constantine became Emperor of the West; he later defeated Licinius at Chrysopolis (on the Asiatic side of the Bosphorus) and eventually ruled the East and West together, exiling Licinius to Galerius and later having him assassinated.
In 324 Constantine defeated Licinius and became ruler of the greater East as well as the West; he decided the empire needed a capital in the East, closer to Persia.
Constantine chose Byzantion (the Greek colony that became Byzantium) on the European shore of the Bosphorus, with a long history of controlling Black Sea–Mediterranean trade routes.
Byzantion, built on an elevation with a well-protected harbour (the Golden Horn), commanded sea routes and overland routes between West and Asia; it was strengthened by the late third century under Septimius Severus.
In traditional ceremony (324 CE), a line was ploughed to mark out new land walls, quadrupling the city’s extent to about eight square kilometres, and defining gates along the western wall and along the Marmara and Golden Horn.
After six years of intensive construction, the city of Constantine (Constantinople) was inaugurated on 11 May 330 CE, with grand civic festivals and races at the Hippodrome.
Urban Fabric, Monuments, and Institutional Transformation in New Rome
The Hippodrome became a central civic space and an open-air museum adorned with Greaco-Roman statues and victory trophies; four bronze horses stood above the starting gates to inspire participants.
The city attracted craftsmen, merchants, and adventurers; a new court needed educated officials to run administration and celebrate the Christian emperors’ rule.
Constantine minted the solidus (nomisma) as a new 24-carat gold coin; introduced in the West in 309, it became a stable, high-fineness coin for over seven centuries.
Constantine’s coinage adapted Roman symbols of Rome and Victory to include Tyche (Fortuna) of Constantinople; she appeared enthroned with a crown of battlements and a cornucopia, symbolizing the city’s wealth under male power.
Imperial coinage carried the city’s symbol into wide circulation; over time Christian symbols replaced ancient pagan ones: the Cross appears first in the sixth century and a Christ portrait appears in the late seventh century (illustrated as plate 11a).
The physical layout mirrored Old Rome: fourteen regions and seven hills; straight avenues leading from the Forum to gates; ancient sculptures decorate squares; a monumental acropolis overlooking the Bosphorus featured temples to Rhea and Fortuna Romae; a dramatic porphyry column topped by a pagan Apollo statue symbolized imperial power.
The Serpent Column (from Plataea, 479 BC) and an Egyptian obelisk from Karnak were brought to the Forum; the Hippodrome displayed Greek-Roman imagery and imperial victories.
Constantine relocated senatorial families east and granted land and privileges to form a new Constantinopolitan Senate; bread tokens were tied to housing construction as a symbol of provision and status.
The city built a reliable water supply via long aqueducts and cisterns; grain silos and other food infrastructure supported predictable provisioning of the population.
The new capital’s religious landscape evolved: the cross became more prominent, and in the seventh century a portrait of Christ appeared on gold coins; later, nomisma coins became the principal gold currency in the Middle Ages and gold coins circulated widely even in northern Europe and across Asia.
Constantine’s foundation drew upon Roman architectural and urban traditions, providing a new political center that could rival Rome; the city’s walls and harbor made it a formidable fortress and administrative hub.
The new capital attracted senatorial families Eastward, encouraged mobility, and fostered a new urban elite but retained a degree of social mobility: aristocrats and plebeians could rise based on talent; slaves continued to be beaten as a social underside.
Constantine’s programs included reinforcing the city’s water supply, providing free bread to inhabitants (via bread tokens), and distributing food, clothing, and money to residents of the new capital.
Religion, Pilgrimage, and the Imperial-Religious Synthesis in Constantinople
The question of Constantine’s religious belief is debated: accounts by Eusebius (ca. 313–340) emphasize Christian devotion; secular historians note the possible veneration of Sol Invictus (the unconquered sun) alongside, or prior to, Christianity.
In 312/13, Constantine acted toward Christian possessions in Rome: returning possessions confiscated during persecutions to bishops, suggesting a marked shift toward Christian support by imperial policy.
While Constantine supported Christian leaders and funded churches, his sons permitted pagan cults to exist in some forms, including a temple in Italy dedicated to the imperial family with priests for old pagan sacrifices; other temples had their statues removed and precious metals stripped.
The transition to Christian practice favored bloodless sacrifice and transformations in ritual practice; the shift toward Christian rites did not occur instantaneously but over time as pagan sacrifice diminished.
Constantine’s mother Helena (c. 326) traveled to the Holy Land and founded churches at Bethlehem (over the Nativity manger) and Jerusalem (over Golgotha, near the True Cross); this pilgrimage pattern set a precedent for later imperial pilgrimage (hostels and hospitals were built to support pilgrims).
Helena’s pattern influenced later travelers and pilgrims; Constantine himself re-embarked on pilgrimage in 335, dedicating shrines to the Saviour and attending a council in Jerusalem; his thirtieth year of rule was celebrated in that context.
Constantine was buried in a mausoleum intended for relics of the twelve Apostles, following Christian rites replacing Roman cremation; his adopted image as equal to the Apostles reflects the early Christian imperial cult.
His sons continued to collect relics (e.g., the veil, girdle, and shroud of the Virgin at Blachernai) and to grant annual rites of censing, candle lighting, and prayer at relic tombs, reinforcing the notion of a perpetual Christian succession for imperial rule.
A naming pattern emerged: many later emperors were named Constantine (eleven), with others named Michael, John, and Leo; such naming reinforced the link between founding emperor and successors.
The cult of Constantine and Helena evolved into a model for Christian kingship; later medieval depictions often place Constantine and Helena flanking the True Cross in frescoes and legends.
The Chalcedonian settlement of 451 and later ecclesiastical developments helped mold the emperor’s role as a Christian ruler; by the 5th century, rulers like Marcian and Pulcheria were likened to a new Constantine and Helena, linking imperial power with sanctified saintly authority.
The Bulwark Against Islam: The Seventh-Century Crisis and the Emergence of a New World Order
The seventh century brought near-destruction from desert tribes (Arabians) alongside ongoing Persian warfare; Byzantium faced Slav raids in the Balkans and a long Persian war across the eastern frontier.
In the 620s, Slavs and Avars captured major Balkan cities (e.g., Singidunum/Belgrade) and advanced south; Thessalonike faced siege, and large portions of the Balkans and western Peloponnese fell temporarily from imperial control.
Persian campaigns devastated Asia Minor; Jerusalem and Antioch fell to Persian forces; the True Cross was carried into captivity, then recovered by Herakleios after a long campaign (622–628). He restored order and defeated Persia, recapturing Nineveh and Ctesiphon.
Despite these Persian successes, the Arabs rose to become Byzantium’s most persistent enemy, conquering Syria, Palestine, and Egypt (Jerusalem and Bethlehem included) within a decade, radically altering imperial space and economics.
The Arab conquests were aided by new mobility: desert-dominant tactics, rapid raiding, effective siege technologies, and the Islamization of conquered peoples; many Christians and Jews paid jizya (extra taxes) but could retain their faith as dhimmi, depending on local policy.
By 630’s-640s, the Arabs established Damascus as a base and extended power to the Levant and Egypt; Jerusalem fell to the Caliph Umar in 634–44; Dome of the Rock (691/2) was built on the Temple Mount in Jerusalem with Byzantine mosaic craftsmanship and Qur’anic inscriptions, signaling a new religious and political order.
The Dome of the Rock inscriptions emphasize Islamic monotheism and critique Christian Trinity doctrine; the interior mosaics reflect Byzantine artistic influence combined with Islamic theological messaging.
The Arab expansion altered Mediterranean trade and led to a threefold division of influence: Islamic South, Byzantine Christian East, and Latin Christian West, changing Europe’s political and economic landscapes.
The consolidation of Islamic power around the Qur’an and monotheism encouraged a new global distribution of power, with Byzantium forced to adapt rather than discard its core identity.
The Early Medieval Byzantine State: Thematic Military Administration and Administrative Adaptation
To defend a shrinking realm, Byzantium developed the themata (military themes): administrative-military districts intended to sustain defense and governance.
The earliest three themes identified circa 630–80: Anatolikon (Eastern), Armeniakon (Armenian), and Opsikion (from obsequium, a military term), followed by Thrakesion (western Asia Minor), Thrakesion on the western side, and Kibyrraioton (Antalya port region); a separate naval force, Karabisianoi, patrolled the Aegean but did not form a thematic structure.
The strategos (general) came to wield combined military and civil authority, with civilian officials subordinate to him; katalogoi listed soldiers and helped with land measurement, taxation, and revenue collection—forming the administrative skeleton that defined Byzantine governance for centuries.
Facing significant losses in Egypt, Syria, and Palestine, Byzantium still issued reliable gold coinage (the nomisma) and maintained a credible legal framework; Latin imperator designation gradually yielded to Greek basileus.
Herakleios reformed mid-seventh-century law and currency; the Arabs controlled Cyprus, Cos, and Rhodes by mid-century, raiding Aegean shipping and coastal sites; Constans II (641–68) moved his court to Syracuse in Sicily after defeat off Asia Minor’s southern coast; he received papal gifts in Rome and attempted to reform imperial lands and churches in Italy.
Constantine IV (reigned 668–685) faced continued Arab attacks and used Greek fire effectively in naval battles; he stabilized the frontier by leveraging inland mountain tribes (Mardaites) and negotiated a thirty-year peace with Caliph Mu’awiya, paying annual tribute, and capturing captives and horses as part of the agreement; he aligned with Lombards and Avars in Europe and supported his son Justinian II as successor.
The Arab threat shifted focus to Slavs in the western provinces; Slavonic settlement expanded and integrated with the empire, particularly in Hellas (central Greece) with the creation of a thema and local bishoprics; Greek language and Orthodox culture spread through the Slavic communities.
Slavic integration into the empire included mixed outcomes: intermarriage, adoption of Christianity, Greek language learning, and taxation under Constantinople; some Slav populations maintained separate identities (e.g., Niketas, Patriarch of Constantinople, was Slav; Thomas the Slav was a military leader who sought the throne).
The evolution of family names (e.g., Keroularios, candle-maker) illustrates social advancement and the emergence of a more dynamic Byzantine identity; Byzantium distinguished itself from other states with a consciousness of genealogy and personal relations.
The Church played a central role in legitimating imperial rule; ecumenical councils and theological disputes (e.g., Monotheletism) tested imperial authority and church-state relations.
The Monotheletism Crisis, Ecumenical Councils, and Iconography
Monotheletism (one will) was promoted to resolve Christological disputes; this doctrine faced strong opposition in Byzantium and the West and failed to win over Monophysite communities.
The Trullan (Trullo) Council of 692, convened by Justinian II, issued 102 canons to enforce coherent belief and regulate ecclesiastical practice; it addressed economic and social concerns (e.g., banning certain public dances and theatrical practices) and regulated religious art: canons 100 and 82 restricted pagan imagery and required Christ’s human form to be depicted in art as Incarnate, not solely as the Lamb of God.
Iconography and religious art gained significance in Byzantium, with icon painters contributing to a developing religious artistic tradition; Justinian II’s reign saw the introduction of a new gold coinage displaying Christ’s portrait on the front and the emperor’s portrait on the back (plates 11a and 11b).
The church’s authority supported imperial governance; the stability of the empire during the early Islamic threat depended on a synergetic church-state relationship.
The Long Shadow: Pirenne, Islam, and Europe’s Eastern Frontier
Since the 1930s, Henri Pirenne argued that the Arab expansion disrupted Mediterranean trade, forcing northern Europe to develop economically apart from the south, leading to the Hanseatic League; he argued that Muhammed’s influence indirectly shaped European development (Pirenne’s thesis).
However, Pirenne did not fully credit Byzantium’s role in halting Arab expansion through Asia Minor, the Dardanelles, and into Europe; Byzantium’s resistance preserved a Christian East that would later influence Europe’s formation.
The empire’s survival created a threefold division: an Islamic South, a Byzantine Christian East, and a Latin Christian West; Byzantium’s defense of Asia Minor prevented a rapid Arab penetration into Europe, including into the Balkans and possibly Rome itself.
The Arab conquests were significant but did not erase the Christian East or the Byzantine state; Byzantium adapted by narrowing its borders and transforming governance toward a medieval framework while maintaining Roman imperial traditions and its Greek inheritance.
The Dome of the Rock and Islamic Architecture as a Symbol of Power Shift
The Dome of the Rock (691/2) in Jerusalem represents a synthesis of Byzantine artistry and Islamic theology, with Byzantine craftsmen producing mosaics and Qur’anic inscriptions announcing monotheism and the non- Trinity message; the monument symbolizes a decisive religious power shift in the Near East.
The Qur’an’s verses and imagery in the Dome of the Rock emphasize Islamic theology (one God, the Prophet Muhammad’s message) and critique Christian Trinity, signaling a new religious order in the Near East.
The Dome of the Rock’s establishment marked a turning point in the Near East’s power balance, affecting Byzantine morale and provoking apocalyptic narratives among Byzantines (e.g., prophecies surrounding the end of time and the last Roman emperor’s fate).
The New Medieval Byzantium: Administrative, Military, and Religious Consolidation
Byzantine resilience depended on a combination of strong fortifications, deep-rooted religious faith, and a Greek-based administrative system that persisted even after territorial losses.
The Taurus Mountains protected Asia Minor from direct continental invasion; Byzantium used a frontier model and new military districts to organize defense and taxation, while retaining the old Roman legal system.
The empire adapted to a reduced but stable medieval state by emphasizing orthodox Christianity, Roman imperial traditions, and Greek heritage; dynastic rule became essential to maintaining continuity during chaotic transitions.
The Catholic and Orthodox churches, together with the Senate, provided governance in moments of crisis, but rising military leadership within the themata gradually displaced civilian authority and moved power into the hands of military leaders (695–705 and 711–717), shaping the political landscape of the late antique to medieval transition.
Byzantium’s defense of Asia Minor and the eastern Mediterranean ensured Christian continuity and prevented the Arab expansion from erasing the Eastern Christian world; this allowed the Slavonic conversions to Byzantium and the establishment of a distinct Byzantine medieval identity.
From a limited base, Byzantium played a pivotal role in shaping Europe’s East–West dynamics; its survival and adaptation prevented a rapid Arab conquest of the Balkans and central Europe, thereby influencing the trajectory of Western and Eastern Christian histories.
Key Figures, Dates, and Concepts (selected reference points)
Constantinople inaugurated: CE.
Edict of Toleration and rapprochement between East and West: CE.
Milvian Bridge victory and cross vision: CE.
Chrysopolis victory over Licinius and consolidation: CE.
Solidus (nomisma) minted: introduced by Constantine in the West in CE; remained the standard gold coin for centuries.
Relations with the Church and relics: True Cross recovered (630), Holy Apostles church and relics together with Helena’s pilgrimages.
Chalcedon Council: CE; Trullo Council (692): CE; Monotheletism debated and condemned.
Arab-Islamic conquests: Jerusalem occupied in ; Dome of the Rock built ; the treaty with Mu’awiya around 678; Umar’s conquest of Jerusalem and sustained campaigns thereafter; the Yarmuk battle in ; Damascus and Syria fell to Islamic forces; Egypt captured in the decades after.
Thematic system: first three themes circa (Anatolikon, Armeniakon, Opsikion), with Thrakesion and Kibyrraioton following; Karabisianoi as naval force; strategos as civil-military authority; katalogoi for taxation and land measurement.
Slavonic integration: Hellas as a thema with local bishops; Slav names noted in sources (e.g., Niketas as Slav; Thomas the Slav).