The reign of Justinian I, from 527 to 565, was the substantial high-water mark of the eastern Roman state's classical-imperial ambition and the substantial moment of its constitutive turn toward the medieval Greek-Christian polity that the German humanists would eventually call Byzantine. The thirty-eight years produced the great codification of Roman law (the Corpus Iuris Civilis), the great church (the Hagia Sophia, dedicated 537), the brief reconquest of the western provinces (North Africa, Italy, parts of Spain), the suppression of the Nika revolt (532), the persistent attempt to resolve the Christological controversies, and the Plague of Justinian (541–549) — the first attested pandemic of Yersinia pestis in the historical record, which reduced the eastern population by perhaps a quarter and from which the empire's military and fiscal capacities never substantially recovered.
The accession and the Nika riots
Justinian, born Petrus Sabbatius in the Dardanian village of Tauresium around 482, was the nephew and adopted heir of Justin I (518–527), an Illyrian peasant who had risen through the army to the throne. The young Justinian had been effectively the senior administrator of his uncle's reign from 518 onwards. His own succession on Justin's death in August 527 brought to power a man who had already designed substantially the legislative and administrative programme he would prosecute for the next four decades, with the close partnership of his wife Theodora, the former actress whose political acumen the contemporary sources (Procopius's Secret History excepted) substantially credit.
The principal political crisis of the reign came early. The Nika revolt of January 532 — produced by the political tension between the chariot-racing Blue and Green factions of Constantinople, by the substantial unpopularity of the praetorian prefect John of Cappadocia and the quaestor Tribonian, and by the persistent dynastic claims of the surviving Anastasian family — produced five days of substantial urban violence in which the rioters acclaimed Hypatius (a nephew of Anastasius I) as alternative emperor and burned down a substantial portion of central Constantinople, including the senate house and the original Hagia Sophia. Justinian's near-flight from the city, his decision to remain (substantially attributed to Theodora's counsel — "the imperial purple is the noblest shroud"), and his order to Belisarius and Mundus to clear the Hippodrome by force, produced approximately thirty thousand civilian deaths in a single day and the consolidation of his personal authority. The destroyed central districts were rebuilt on a substantially grander scale, with the new Hagia Sophia at the centre of the programme.
The Code
The codification project under Tribonian, the master jurist of the reign, produced the Corpus Iuris Civilis in four parts between 529 and 534: the Codex Justinianus (a redaction of imperial constitutions from Hadrian through the present), the Digesta or Pandectae (a selection of classical juristic opinions arranged systematically), the Institutiones (a textbook for first-year law students), and the Novellae (the post-534 constitutions issued by Justinian himself, predominantly in Greek). The substantive achievement was the rationalisation and consolidation of approximately a thousand years of legal accretion into a single coherent corpus. The substantive consequence was that, when the Italian universities of the eleventh and twelfth centuries rediscovered the Justinianic codification, the western legal tradition acquired the Roman-law foundation on which the modern continental codes (the Napoleonic, the German, the Italian) are substantially built.
The reconquest of the West
The military programme to recover the lost western provinces was prosecuted from 533 to 555 by a small number of expeditionary forces under the principal commands of Belisarius (533–540, 544–548) and Narses (552–555). The North African campaign of 533–534 destroyed the Vandal Kingdom in approximately six months: Belisarius landed at Caput Vada with approximately eighteen thousand troops in September 533, defeated the Vandal field army at Ad Decimum on the 13th of September and at Tricamarum on the 15th of December, captured King Gelimer in March 534, and re-established Roman administration of the African provinces with substantial efficiency. The substantive Vandal kingdom — which had ruled Carthage and the African provinces for ninety-five years — disappeared from the historical record within six months of the Roman landing.
The Italian campaign of 535–554 was substantially more complicated. The initial campaign of 535–540 under Belisarius produced rapid early successes — the capture of Sicily (535), Naples (536) and Rome itself (December 536) — but the substantial Ostrogothic counter-attack under Witiges (the siege of Rome of 537–538), the recall of Belisarius in 540, the resurgence of the Goths under Totila in the 540s, and the disruptions of the plague substantially extended the war. The final phase under Narses (552–554) destroyed the Gothic kingdom at the battles of Taginae (552) and Mons Lactarius (553), and the Roman administration of Italy was reconstituted under the Pragmatic Sanction of 554. The Spanish reconquest, conducted as a sideshow during the Italian war, produced the recovery of a south-eastern coastal strip including Cartagena and Malaga in 552.
The total cost of the reconquest — in money, manpower and administrative attention — was substantial and the substantive long-term gain was limited. The Italian provinces never fully recovered from the twenty years of warfare; the Lombard invasion of 568, three years after Justinian's death, would substantially expel the eastern administration from northern Italy within a generation; the African provinces would be lost to the Arab conquests in 698; the Spanish reconquest would be progressively reduced and finally extinguished in 624. The Justinianic reconquest's substantive legacy was the institutional template — the exarchates of Ravenna and Carthage, the Italo-Byzantine administration of southern Italy that persisted to 1071 — and the substantial cultural-religious continuity that the Italian Catholic Church and the Sicilian-Calabrian Greek-speaking communities would maintain into the medieval period.
The Hagia Sophia
The Great Church of Constantinople — the third on the site, after the original Constantinian foundation of 360 and the Theodosian rebuilding of 415, both destroyed in successive riots — was constructed between 532 and 537 under the architectural direction of Anthemius of Tralles and Isidorus of Miletus. The substantial structural innovation was the use of pendentives to mount a hemispherical dome on a square plan, producing a clear span of approximately thirty-three metres at a height of approximately fifty-five metres. The construction took five years and ten months. The dedication of December 27th, 537, was attended by Justinian personally, who is reported (in a contemporary tradition) to have exclaimed "Solomon, I have surpassed thee" — the historicity of the report is doubtful but its substance is not.
The substantive cost of the Hagia Sophia — substantial even by the standards of late-antique imperial building — was met from the windfall of the African campaign (the captured Vandal treasury) and from a special property tax on senatorial estates. The original dome of 537 partially collapsed in the earthquake of 558 and was rebuilt by 562 in a substantially modified form (the present dome is the second one, with subsequent buttressing). The building has survived as the principal monument of the eastern Christian architectural tradition, served as the model for substantially all subsequent Orthodox great churches, and continues to stand in Istanbul as a museum and (since 2020) a mosque.
The Plague of Justinian
The arrival of Yersinia pestis at Pelusium on the Egyptian coast in 541, and its progressive spread through the Mediterranean basin between 541 and 549, produced the first attested European pandemic of plague in the historical record. The substantive epidemiological evidence — modern genetic analysis of bacterial DNA from sixth-century burial sites in Bavaria, Spain and elsewhere — has identified the pathogen as the bubonic-plague bacterium that would also produce the fourteenth-century Black Death and the nineteenth-century third pandemic. The fatality estimates have been substantially argued about by historians and demographers; the most-cited recent estimates suggest a substantial population reduction across the eastern Empire of between fifteen and twenty-five per cent in the principal outbreak years.
The substantive consequence was the substantial reduction of the imperial tax base, the substantial reduction of the available military manpower, the substantial disruption of the food-supply systems, and the substantial constraint on the imperial government's capacity to sustain the substantial military commitments of the reconquest programme. The post-549 phase of the Italian war was conducted at a substantially reduced operational tempo by substantially reduced expeditionary forces, and the reconstruction of the imperial fiscal and military system was a substantial undertaking for the successor reigns of Justin II (565–578) and beyond. The substantial assessment of modern historiography is that the plague is a substantial part of the explanation for the limited long-term durability of the Justinianic reconquest, and for the eastern Empire's substantial weakness in the face of the seventh-century Arab onslaught.
Justinian died on the 14th of November 565, aged about eighty-three, after a reign of substantial achievement and substantial accumulated cost. The substantial achievements — the Code, the Hagia Sophia, the reconquest, the doctrinal interventions, the substantial body of administrative reform — defined the form of the medieval eastern Empire. The substantial costs — the military exhaustion, the fiscal depletion, the demographic catastrophe of the plague — set the substantial limits within which his successors would operate. The Arab conquests that would begin sixty-five years later, in 632, would arrive against an eastern Empire that the Justinianic exertions had substantially over-extended.
End of Chapter II