Did Diocletian’s reforms save or weaken the Roman Empire?

The short answer

• Answers to the third century. The repeated usurpations and failures of the third century shaped Diocletian’s choices. Four rulers addressed the struggle for a single throne; separate civil and military offices limited the power of governor-generals. Taxes in goods answered debased coinage, while sacred ceremony raised the dignity of an office whose holders had so often been killed. These measures were designed for dangers already experienced. Barbarian settlement and the west’s thinner economy would present further tests.
• Persecution and the church. From 303 to 311 the Great Persecution sought to break Christianity. Authorities burned scriptures, imprisoned clergy and required Christians to sacrifice. Yet Christians were connected across communities, held official posts and included people willing to die for their faith. The campaign failed; an eastern edict ended persecution in 311. Constantine’s support, a decade after the campaign began, brought the emperor into partnership with a network the state had been unable to destroy.
• An eastern centre. Constantinople did not create the east’s importance. Diocletian had governed from Nicomedia and visited Rome only once: cities, revenues, recruits and dangerous frontiers had already drawn the court eastward. Constantine gave that orientation a new capital. When eastern and western courts were formally separated in 395, the east had a defensible capital and resources to garrison it; the west retained Rome’s prestige and its exposure. Chapter 11 follows their unequal fortunes.
• An organised Christian community. Roman traditional religion joined many local cults to civic life. Christianity connected communities differently. Bishops in cities, councils, letters and charitable work gave the church an infrastructure that crossed social and ethnic divisions. Its universal membership and account of authority under one God also offered a way to relate religious and imperial power. Constantine gained organized partners, and their disputes came with them. Chapter 12 follows the church beyond the western state it joined.

What it changed

The cost of government. A larger government had to be paid for. Courts, officials and soldiers depended on taxes and compulsory obligations, including those placed on guilds and tenant farmers, or coloni, tied to estates. A contemporary pamphleteer complained of “more tax-eaters than taxpayers,” Diocletian’s Price Edict of 301 attempted to control inflation by fixing prices, but a prescribed price could not ensure that goods would be offered at it. Did the heavier state preserve the empire or damage the economy and loyalty it needed? Chapter 11 returns to the question in the west.

Church and imperial power. By sponsoring the church, emperors became involved in its disputes: Constantine called bishops to Nicaea to address one of them. Church leaders could also challenge imperial conduct. Within eighty years Bishop Ambrose required Theodosius to perform public penance after Thessalonica. The alliance made cooperation possible, while giving religious and political authorities reasons to contest one another. Chapter 12 considers that relationship’s longer history.

An eastern capital. Constantinople acquired its own court, senate, mint and grain supply, including grain redirected from Egypt. The eastern government could therefore operate from a center less dependent on Rome. Compare its foundation in 330 for a united empire with the formal division in 395 and the end of the western imperial line in 476. The eastern empire survived until 1453. The capital was only part of that difference, but its defensible position and resources helped the eastern court govern and defend itself.