The Ancients – Emperor Diocletian and the Great Persecution
Host: Tristan Hughes
Guest: Dr. David Gwynn
Date: December 21, 2025
Overview
This episode dives deep into the reign of Emperor Diocletian, exploring his rise from humble Balkan origins, his transformative impact on the Roman Empire, the establishment of the Tetrarchy (rule of four), and, most controversially, the Great Persecution of Christians. Dr. David Gwynn, returning as a fan-favorite expert, provides a nuanced account of Diocletian's legacy, weaving together political reforms, administrative innovations, and the infamous religious crackdown that defined his later years.
Key Discussion Points and Insights
1. Diocletian’s Place in Roman History
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[03:01] Dr. Gwynn emphasizes Diocletian’s pivotal role:
“Diocletian is... unquestionably in the top 10 of great Roman emperors, forever distorted by the fact that our Christian sources despise the man for the great persecution…” — Dr. David Gwynn -
Diocletian, along with Constantine, is considered an architect of the "later Roman Empire" after the third century crisis.
2. Challenges with Historical Sources
- [03:45]
- There’s no continuous classical narrative for Diocletian’s reign.
- Historians must rely on archaeological remains, imperial laws, propaganda (panegyrics), and hostile Christian writings, particularly Lactantius and Eusebius.
3. Diocletian’s Rise to Power
- [05:27]
- Born Diocles, likely c. 240 AD, of peasant background in the Balkans.
- Rose through the army during the turbulent third century.
- Became head of the imperial bodyguards; ascended amid mysterious deaths of preceding emperors.
- Seized power in 284 AD and would uniquely abdicate in 305.
4. The State of the Empire in 284
- [09:44]
- Diocletian inherited a recently reunified but still fragile empire after decades of fragmentation and crisis.
5. Power-Sharing: From Diarchy to Tetrarchy
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[12:31, 13:57]
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Immediate need to delegate authority; appoints Maximian (another Balkan soldier) as co-emperor.
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Their power-sharing is ideologically styled as “Jovius and Herculius,” likened to Jupiter and Hercules (father/hero dynamic).
“What’s the classical pagan equivalent to Batman and Robin? Jupiter and Hercules... Diocletian becomes Jovius, Maximian is Herculius.” — Dr. David Gwynn [14:05]
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[17:24]
- Stresses of rule necessitate further delegation. Diocletian breaks precedent by establishing the Tetrarchy in 293:
- Two senior Augusti: Diocletian (East), Maximian (West)
- Two junior Caesars: Galerius (East), Constantius Chlorus (West)
- The structure is hierarchical, not egalitarian. It’s built to prevent regional usurpation and manage persistent threats.
- Stresses of rule necessitate further delegation. Diocletian breaks precedent by establishing the Tetrarchy in 293:
6. Administration and Reform
- [27:30]
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Administrative reform: Diocletian doubles the number of provinces, making each smaller and easier to control.
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Separation of civil and military authority at provincial levels to reduce risks of rebellious governors.
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Emergence of the diocesan system, with vicarii overseeing groups of provinces.
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The process becomes more bureaucratic and hierarchical; access to the emperor is more restricted.
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The army is expanded and restructured for flexibility; legions are smaller, but there are more of them, and a stronger emphasis on cavalry.
“The size of a legion seems to have been significantly reduced... more like 1,000 [men],” — Dr. David Gwynn [33:50]
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7. The Imperial Image and Propaganda
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[21:48]
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Diocletian’s propaganda stresses harmony (“concordia”) among rulers.
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Use of art and monuments, most famously the porphyry statues of the tetrarchs (now in Venice), which symbolize their unity while hinting at hierarchy.
“A group of four statues… in two pairs, each embracing the other… These are soldier emperors. But the four figures aren’t actually totally identical because two of them have stubble… the two seniors.” — Dr. David Gwynn [24:00–24:48]
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Coinage and monuments use established imperial and divine imagery, solidifying legitimacy.
8. The Great Persecution: Motives and Execution
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[36:32]
- By end of the third century, Christians made up perhaps 10% of the empire (~6 million in 60 million).
- Previous persecutions (Decius, Valerian) were limited and unsuccessful.
- Diocletian, a staunch pagan, launches systematic persecution only after stabilizing other crises.
- [41:27]
- First targets the Manichaeans (302), then Christians (303).
- The Great Persecution’s aim: force Christians to conform, not mass extermination.
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[44:41]
- Eyewitness accounts: Lactantius (North Africa, Nicomedia) and Eusebius (Caesarea).
- Both blame Galerius as instigator, but Diocletian bears the historic reputation.
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[48:15]
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The impact was more psychological than fatal; local populations, governors, and soldiers were largely apathetic.
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The size and resilience of the Christian community and lack of broad public support rendered the persecution ineffective.
“The strength of the Church. Six million people is too many. This is whatever Diocletian would like to achieve, not a totalitarian state, because it just doesn’t have the resources to be one.” — Dr. David Gwynn [49:07]
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9. End of Diocletian’s Rule and Legacy
- [52:05]
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Diocletian and Maximian both abdicate in 305 (Maximian unwillingly).
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Diocletian retires to his palace in Split (modern Croatia); dies circa 311/312.
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The Tetrarchic system collapses soon after as dynastic ambitions (e.g., Constantine, Maxentius) reignite civil wars.
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Dr. Gwynn: The stability of the Tetrarchy was Diocletian’s achievement alone; without his control, the system falters.
“It hasn’t worked for the previous decade because it’s a great system. It’s worked because the man who built it controlled it…” — Dr. David Gwynn [54:40]
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Notable Quotes & Memorable Moments
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On Diocletian’s legacy:
“Forever distorted by the fact our Christian sources despise the man for the Great Persecution…”
— Dr. David Gwynn [03:01] -
On the Tetrarchy’s symbolism:
“What’s the classical pagan equivalent to Batman and Robin? Jupiter and Hercules… Diocletian becomes Jovius, Maximian is Herculius.”
— Dr. David Gwynn [14:05] -
On the failure of the Great Persecution:
“The vast majority of the population of the Roman Empire did not want it to happen... if you don’t have that local upsurge, the persecution cannot be effective.”
— Dr. David Gwynn [49:07–49:40] -
On Diocletian’s abdication:
“He abdicates as an emperor and voluntarily stands down, as does Maximian. Although we get the distinct impression Maximian didn’t want to and Diocletian didn’t give him the choice.”
— Dr. David Gwynn [52:05] -
On his peaceful retirement:
“He had a palace built for himself at Split... that’s where he went. And... he died in 311 or 312. So he’s actually lived for five or six years, completely untroubled by absolutely everybody. Except that apparently Galerius occasionally dropped by for some advice...”
— Dr. David Gwynn [53:56]
Timestamps for Important Segments
- [03:01] – Diocletian’s place in Roman imperial history
- [05:27] – Diocletian’s Balkan origins and rise through military ranks
- [09:44] – State of the empire Diocletian inherits
- [13:57] – Appointment and roles of Maximian, Constantius, and Galerius
- [17:24] – Creation of the Tetrarchy: senior/junior roles and geography
- [21:48] – Imperial ideology and propaganda
- [27:30] – Administrative and military reforms, expansion of bureaucracy
- [36:32] – Christianity and religious policy before the Persecution
- [41:27] – Motives for the Great Persecution; targeting Manichaeans
- [44:41] – Eyewitness accounts and casualties of the Persecution
- [48:15] – Why the Great Persecution failed
- [52:05] – Abdication, retirement, and death
- [54:40] – Collapse of the Tetrarchy and Diocletian’s historical judgment
Conclusion
The episode provides a rich, balanced look at Diocletian’s life and impact. While his name is inseparably tied to the Great Persecution, Dr. Gwynn and Tristan Hughes emphasize his reforms, administrative genius, and the bold experiment of the Tetrarchy. Ultimately, Diocletian appears as a transformative but complex figure whose legacy is as much about the re-shaping of imperial structures as about religious intolerance.
For further learning:
- Visit Venice’s St. Mark’s Square to see the Tetrarchic porphyry statues (24:00)
- Read the eyewitness writings of Lactantius and Eusebius for perspectives on the Great Persecution (44:41)
Episode expertly hosted by Tristan Hughes with returning guest Dr. David Gwynn.