Diocletian's reforms aimed to stabilize the Roman Empire after years of crisis. He divided power among four rulers, expanded the army, and overhauled the economy. These changes helped strengthen the empire's defenses and improve its administration.

Constantine's rise marked a turning point for Christianity in the Roman world. He legalized the religion, ended persecutions, and actively supported the Church. This shift set the stage for Christianity to become the dominant faith in the empire.

Diocletian's Reforms and the Tetrarchy

Diocletian's stabilizing reforms

• Administrative reforms
  • Divided the empire into four administrative regions (tetrarchies), each governed by a tetrarch to improve efficiency and responsiveness
  • Increased the number of provinces from 50 to almost 100 to improve local governance, tax collection, and maintain tighter control
  • Separated military and civilian authority to reduce the power of regional governors and prevent them from challenging imperial authority
• Military reforms
  • Expanded the army from about 300,000 to 500,000 soldiers and fortified borders (Limes Moesiae) to better address external threats (Germanic tribes, Sassanid Persians)
  • Created a mobile field army (Comitatenses) to respond quickly to invasions or internal rebellions, separate from the frontier troops (Limitanei)
• Economic reforms
  • Implemented a new tax system (Capitatio-Iugatio) based on land and labor to increase revenue and ensure a more stable income for the government
  • Attempted to control inflation by issuing the Edict on Maximum Prices in 301 CE, which set price ceilings on goods and services
  • Reformed the coinage by introducing new denominations (Argenteus, Nummus) to stabilize the currency and combat debasement
• Social reforms
  • Issued the Edict on Marriages in 295 CE to promote traditional Roman values, encourage procreation, and maintain social order
  • Persecuted Christians (Great Persecution of 303-311 CE) to maintain religious unity and social stability, viewing them as a threat to imperial authority

Tetrarchy and imperial governance

• Diocletian established the Tetrarchy in 293 CE to divide power and responsibilities
  • Two senior emperors (Augusti): Diocletian ruled the East and Maximian the West
  • Two junior emperors (Caesares): Galerius and Constantius Chlorus, who assisted the Augusti and were intended to be their successors
• Power-sharing arrangement aimed to improve efficiency and stability of the empire
  • Each tetrarch was responsible for a specific region (Prefecture), allowing them to focus on local issues and respond to threats more effectively
  • Tetrarchs could consult and support each other in decision-making and military campaigns
• Succession plan to ensure smooth transitions of power
  • Caesares would succeed Augusti upon their retirement (abdication) or death, providing continuity of leadership
  • New Caesares would be appointed by the Augusti to maintain the four-ruler system and prevent power struggles
• Impact on imperial governance
  • Decentralized decision-making and reduced the burden on individual emperors, making the administration more manageable
  • Increased the presence of imperial authority throughout the empire, as each tetrarch had their own court, bureaucracy, and army
  • Set a precedent for shared rulership in the later Roman Empire, influencing the governance structure of the Byzantine Empire

Constantine's Rise and Religious Reforms

Constantine's rise and consolidation

• Constantine's early life and career
  • Son of Constantius Chlorus, one of the tetrarchs, and Helena, Chlorus' concubine
  • Served in the military under Diocletian and Galerius, gaining valuable experience and reputation
• Acclamation as emperor by his troops in 306 CE in York (Eboracum) after his father's death, challenging the tetrarchic system
• Conflict with rival emperors for control of the Western Roman Empire
  • Defeated Maxentius, son of Maximian, at the Battle of Milvian Bridge in 312 CE, allegedly after seeing a vision of the Christian Chi-Rho symbol with the words "In this sign, conquer"
  • Consolidated control over the Western provinces, establishing himself as the dominant ruler
• Alliance with Licinius, the Eastern Roman Emperor, sealed by the marriage of Licinius to Constantine's half-sister Constantia
  • Jointly issued the Edict of Milan in 313 CE, granting religious tolerance and ending the persecution of Christians
• Final victory over Licinius in 324 CE after a series of civil wars, reuniting the Roman Empire under his sole rule
  • Became the sole emperor (Augustus) of the entire Roman Empire, ending the Tetrarchy system
• Established a new capital at Byzantium, strategically located on the Bosporus strait, and renamed it Constantinople in 330 CE

Constantine's Christianity and religious impact

• Constantine's personal belief in Christianity
  • Claimed to have had a vision of the Christian God before the Battle of Milvian Bridge in 312 CE, which led to his conversion
  • Attributed his military successes and political triumphs to divine favor and protection
• Edict of Milan (313 CE), a turning point in the history of Christianity
  • Legalized Christianity and granted religious tolerance throughout the empire, allowing Christians to practice their faith openly
  • Ended the persecution of Christians, which had been particularly severe during the reign of Diocletian (Great Persecution)
• Patronage of the Christian Church
  • Provided financial support for the construction of churches (Lateran Basilica, Church of the Holy Sepulchre) and religious institutions
  • Granted privileges and exemptions to Christian clergy, such as tax exemptions and the right to be tried in ecclesiastical courts
• Involvement in Church affairs and doctrinal disputes
  • Convened the First Council of Nicaea in 325 CE to resolve the Arian Controversy, which questioned the divinity of Jesus Christ
  • Sought to establish a unified Christian doctrine (Nicene Creed) and maintain religious stability within the empire
• Effects on the religious landscape of the Roman Empire
  • Christianity gradually became the dominant religion, enjoying imperial support and patronage
  • Pagan religions and practices began to decline, though they were not immediately suppressed or prohibited
  • Laid the foundation for the spread of Christianity throughout Europe and beyond, as the Roman Empire's influence extended far and wide
  • Established a precedent for the involvement of emperors in religious matters, setting the stage for the complex relationship between Church and State in the centuries to come