On the 20th of November, 284 CE, Diocletian was chosen as Roman emperor. I’ve posted about a number of Roman emperors, Commodus seems to have had the most clicks. Let’s see how Diocletian performs.
Gaius Aurelius Valerius Diocletianus, commonly known as Diocletian, was Roman emperor from 284 to 305 CE and is remembered as one of the most transformative figures in the history of the Roman Empire. His reign, marked by significant political, administrative, and economic reforms, helped stabilise the empire after a long period of crisis that had threatened its very survival. Over roughly two decades, Diocletian reshaped the nature of Roman governance and implemented policies that would leave a lasting effect on the empire, even if some of his measures were controversial.
Diocletian rose from relatively humble origins in Dalmatia, a province on the Adriatic coast, to become a skilled military commander. His ascent to power came during the so‑called Crisis of the Third Century, a period characterised by civil wars, foreign invasions, economic instability, and frequent changes of emperor. In 284 CE, after the assassination of the emperor Numerian and the brief reign of Carinus, Diocletian was proclaimed emperor by his troops. He quickly consolidated his position and began to bring order to the fractured empire.
One of Diocletian’s most notable achievements was the establishment of the Tetrarchy, a new political system designed to address the empire’s vast size and the growing difficulty of defending its extensive borders. The Tetrarchy, implemented in 293 CE, divided imperial authority between two senior emperors, known as Augusti, and two junior emperors, called Caesares. Diocletian ruled as senior Augustus in the East, while Maximian became Augustus in the West. The junior emperors, Constantius Chlorus and Galerius, were appointed to assist and eventually succeed the senior emperors. This system not only ensured more efficient military and administrative control but also aimed to create an orderly succession process, reducing the risk of civil war.
In addition to the Tetrarchy, Diocletian pursued extensive administrative reforms. He subdivided the provinces, creating smaller units to improve governance and reduce the power of provincial governors, which had often been a source of rebellion. These provinces were then grouped into larger units called dioceses, overseen by vicarii, adding a new bureaucratic layer that allowed for closer imperial oversight. The size and complexity of the imperial bureaucracy increased under Diocletian, reflecting his desire for a more structured and centralised administration.
Economically, Diocletian faced the immense challenge of stabilising a currency and economy ravaged by decades of inflation and debasement. He attempted to reform the tax system by making it more regular and predictable, linking taxation to land and population censuses. In 301 CE, he issued his famous Edict on Maximum Prices, which sought to curb inflation by fixing prices for goods and services across the empire. While the edict demonstrated his determination to control the economy and protect ordinary citizens from exploitation, it proved largely ineffective in practice and was widely ignored. Nonetheless, it illustrates Diocletian’s active approach to governance and his willingness to experiment with far‑reaching policies.
Diocletian is also remembered for his religious policies, particularly his role in initiating the Great Persecution of Christians. While earlier emperors had alternated between tolerance and sporadic persecution, Diocletian aimed to reinforce traditional Roman religion as a unifying force for the empire. Beginning in 303 CE, his edicts ordered the destruction of Christian texts and places of worship, and required Christians to sacrifice to the Roman gods or face punishment. This persecution was the most severe the early Church had faced and reflected Diocletian’s belief that the favour of the traditional gods was essential to the empire’s survival. However, the policy ultimately failed to eradicate Christianity and, within a few decades, the faith would receive imperial support under Constantine.
Another remarkable aspect of Diocletian’s reign was his decision to retire voluntarily, something almost unprecedented in Roman imperial history. In 305 CE, citing ill health, he abdicated and withdrew to his palace in Dalmatia, allowing the Tetrarchic system of succession to operate as intended. Although the system quickly fell into civil conflict after his retirement, his abdication demonstrated both his confidence in his reforms and his unique personal character.
Diocletian’s legacy is that of a restorer and reformer who reshaped the Roman Empire in a time of deep crisis. His Tetrarchy stabilised the political situation temporarily, his administrative reorganisations strengthened central control, and his economic measures showed a determination to confront long‑standing problems. While some policies, such as the persecution of Christians and the attempt to enforce fixed prices, were ultimately unsuccessful and controversial, his overall impact on the empire was profound. Diocletian transformed the Roman state from the fragile entity of the third century into a more autocratic, bureaucratic, and resilient system, laying the foundations for the later Byzantine Empire.