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From Administrative Convenience to Permanent Separation
Although the Roman Empire had been ruled by multiple emperors before—under the Tetrarchy and even earlier—the division of the empire in the late 4th century became more formal and enduring. By the end of the reign of Theodosius I in 395 CE, the empire was split into two distinct political halves: the Western Roman Empire and the Eastern Roman Empire, often called the Byzantine Empire by modern historians.
This division shaped the future of Europe and the Mediterranean world for centuries.
Background: Earlier Divisions
The idea of dividing responsibility had existed for generations:
- Diocletian’s Tetrarchy (293–305 CE) first divided the empire into eastern and western halves under two Augusti and two Caesars.
- Constantine the Great dissolved the Tetrarchy but often ruled with co-emperors.
- His sons and successors repeatedly partitioned the empire among themselves.
These earlier divisions were temporary arrangements, but they set a precedent.
Valentinian and Valens (364 CE)
A more official and lasting administrative division emerged in 364 CE, when Emperor Valentinian I appointed his brother Valens as co-emperor.
Division of Power
- Valentinian I ruled the Western Empire, based in Milan and later Trier.
- Valens ruled the Eastern Empire, based in Constantinople.
Each had full control over his half, with separate courts, armies, and administrations. Although the empire remained theoretically united, in practice the two halves functioned as distinct states.
Theodosius I and the Last Unified Rule (379–395 CE)
After the disastrous defeat of Valens by the Goths at the Battle of Adrianople (378 CE), the eastern half faced crisis. Theodosius I was appointed emperor of the East and later ruled the whole empire from 392 to 395 CE.
Key Actions of Theodosius
- Concluded treaties with Gothic federates
- Strengthened the Eastern Empire militarily
- Made Nicene Christianity the official state religion (Edict of Thessalonica, 380 CE)
- Reunited the empire under a single ruler (392–395 CE)
However, this unity was short-lived.
Permanent Division in 395 CE
When Theodosius I died in 395 CE, he divided the empire between his two young sons:
- Honorius became emperor of the Western Roman Empire
- Arcadius became emperor of the Eastern Roman Empire
This division was intended as an administrative arrangement—but unlike earlier divisions, it never reversed. After 395 CE, no single emperor ever again ruled both halves for more than a brief moment.
Why This Division Became Permanent
Several long-term trends reinforced it:
1. Geographical and Administrative Differences
- The East was wealthier, more urbanized, and easier to defend
- The West had larger borders and weaker economic foundations
2. Cultural Differences
- The East increasingly spoke Greek
- The West remained mostly Latin-speaking
3. Economic and Military Imbalance
- The Eastern Empire had stronger finances and could field larger armies
- The Western Empire depended on Germanic federate troops and struggled with invasions
Political Independence
Each court made decisions with little regard for the other.
Over time, the two halves developed distinct identities.
The Western Roman Empire After the Division
The Western Empire faced severe challenges:
- Increasing pressure from Germanic peoples (Visigoths, Vandals, Suebi, Ostrogoths)
- A weakening tax base
- Rivalry and corruption among generals
- The sack of Rome (410 CE) by Alaric’s Visigoths
- Further deterioration leading to the deposition of the last western emperor, Romulus Augustulus, in 476 CE
This marked the traditional end of the Western Roman Empire.
The Eastern Roman Empire After the Division
The Eastern Empire, often called the Byzantine Empire by modern scholars, survived for nearly 1,000 years after the collapse of the West.
Characteristics of the Eastern Empire:
- Strong economy based on trade and urban centers
- Highly organized bureaucracy influenced by Greek and Roman traditions
- A powerful and flexible military system
- Centered on Constantinople, one of the world’s greatest fortified cities
- A Christian imperial culture that evolved into Eastern Orthodoxy
Notable rulers included Justinian I, Heraclius, and many others.
Significance of the Division
The division of 395 CE had long-lasting consequences:
Political
- Europe’s political landscape fragmented into various kingdoms in the West
- The East continued Roman state traditions for centuries
Cultural
- Latin West and Greek East developed separate cultural and religious identities
- Eventually contributed to the Great Schism (1054 CE) between Catholic and Orthodox Christianity
Historical Legacy
- The Western Roman Empire fell, but its traditions influenced medieval Europe
- The Eastern Roman Empire preserved Roman law, culture, and administration deep into the Middle Ages
Conclusion
The division of the Roman Empire in 395 CE marked the transition from the unified ancient empire to a world of East and West—a division that shaped the development of Europe, the Mediterranean, and Orthodox and Catholic Christianity for more than a millennium.