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Home / Roman Emperors /

Emperor Diocletian

Written by: Kate Zusmann

Bust of Emperor Diocletian

Diocletian was a Roman emperor from 281 to 305 AD. When Emperor Philip the Arab was defeated in 249, the empire endured over three decades of inefficient emperors. Moreover, the ancient Roman Empire suffered from financial and military problems. There were many attacks along the Danube River and from the eastern provinces. From 284, Diocletian completely changed the previous plight of the Empire.

Contents

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  • Things to Know about Diocletian
    • What did Diocletian do for Rome?
    • What is Diocletian most famous for?
    • What architectural achievements are associated with Emperor Diocletian?
    • What is Diocletian’s palace known for?
    • What was the purpose of the Baths of Diocletian?
    • Why is Diocletian important to the Byzantine Empire?
    • Why did Diocletian decide to split the empire?
    • How did Diocletian try to stop the fall of Rome?
  • Early Life of Diocletian
    • Death of Numerian
    • Conflict with Carinus
  • Emperor Diocletian
    • Divided empire
  • Internal Administration
  • Christians
  • Interesting Facts about Diocletian
  • Death of Diocletian

Things to Know about Diocletian

What did Diocletian do for Rome?

Diocletian implemented significant reforms and policies that transformed Rome. He restructured the government, introduced administrative and military reforms, and stabilized the economy. Diocletian's reign saw the construction of monumental buildings, such as the Baths of Diocletian, and his division of the empire laid the foundation for its future governance and the rise of the Byzantine Empire.

What is Diocletian most famous for?

Diocletian is most famous for his administrative and military reforms during his reign as Roman emperor from 284 to 305 AD. His introduction of the tetrarchy, the division of the empire into four parts, and his efforts to stabilize the economy through currency reforms and price controls are among his notable achievements. Diocletian's influence on the governance and succession of the empire left a lasting impact.

What architectural achievements are associated with Emperor Diocletian?

Emperor Diocletian left a lasting architectural legacy, most notably the Diocletian's Palace in Split, Croatia. This vast complex showcased Roman grandeur and housed a palace, administrative offices, and military barracks. Its architectural features include impressive courtyards, intricate mosaics, and the well-preserved Peristyle. The palace remains a UNESCO World Heritage site and a testament to Diocletian's architectural vision.

What is Diocletian’s palace known for?

Diocletian's palace, located in modern-day Split, Croatia, is known for its remarkable architecture and historical significance. Built as a fortified complex, the palace served as Diocletian's residence and administrative center. It features impressive Roman elements, including grand courtyards, intricate mosaics, and impressive columns. Today, the palace remains a popular tourist attraction and a testament to Diocletian's grandeur.

What was the purpose of the Baths of Diocletian?

The Baths of Diocletian, located in Rome, were the largest public baths in ancient Rome. Built between 298 and 306 AD, they served as a gathering place for socializing, bathing, and exercise. The baths were a grand architectural feat, providing not only hygienic facilities but also a cultural and recreational hub. They showcased Diocletian's wealth, power, and desire to provide amenities for the Roman people.

Why is Diocletian important to the Byzantine Empire?

Diocletian's impact on the Byzantine Empire is significant. His administrative and territorial reforms, including the division of the empire into Eastern and Western regions, influenced the later development of Byzantine governance. Diocletian's establishment of an Eastern capital at Nicomedia and his administrative restructuring laid the foundation for the Byzantine rule, which would continue to flourish in the Eastern Mediterranean for centuries.

Why did Diocletian decide to split the empire?

Diocletian decided to split the empire primarily for administrative and governance purposes. He believed that the Roman Empire had become too vast and complex for a single ruler to govern effectively. By dividing power and appointing co-emperors, known as the tetrarchy, Diocletian sought to improve governance, manage the empire more efficiently, and ensure a smooth transition of power.

How did Diocletian try to stop the fall of Rome?

Diocletian implemented various measures to halt the decline of the Roman Empire. He enacted economic reforms to stabilize the economy, including the introduction of price controls and currency reforms. Diocletian strengthened the military by expanding and reorganizing the army, enhancing border defenses, and suppressing internal revolts. While his efforts brought temporary stability, the fall of Rome would ultimately occur in the centuries that followed.

Early Life of Diocletian

Diocles, later known as Diocletian, was born in 245 AD in the Balkan province of Dalmatia. His parents were of low status. However, he rose progressively through the ranks and eventually became a member of an elite corps within the Illyrian army. Later, Diocletian became an army commander in Moesia, which was an award for his talent. In 283, he joined the Roman Emperor Carus in Persia, where he was one of the bodyguards or “protectores domestici,” the elite cavalry force attached to the Imperial household. This post earned him the position of consul in 283. Moreover, Diocletian took part in Carus’ later Persian campaign.

Death of Numerian

Carus died on mysterious occasions. He was believed to have been killed by Persian soldiers. His sons Numerian and Carinus were left as the new “Augusti.” Carinus went to Rome from his post in Gaul as imperial commissioner in 284 and became a legitimate Emperor in the West. Numerian stayed to rule in the East. The Sassanid king Bahram II wanted to establish his authority and tried to field an army against the brothers. By 284, Numerian reached Emesa (Hons) in Syria, where he was in good health. However, later he suffered from an inflammation of the eyes. Numerian traveled in a closed coach when his army smelled an odor emanating from that coach during the trip to Bithynia. They opened it and found Numerian dead. Most probably, this death was a result of an assassination.

Thus, Numerianus’ generals and tribunes called a council for the succession, where Diocles was chosen a new emperor

Conflict with Carinus

Diocletian and Lucius Caesonius Bassus were chosen as consuls. Bassus was a member of a senatorial family from Campania and a former consul and proconsul of Africa. Moreover, he had an experience in areas of government where Diocletian didn’t have any experience. Most probably, Bassus chose Diocletian as consul as a sign of rejection of Carinus’ rule in Rome. In addition, in 284-285, Diocletian’s armies met Carinus’ across the river Margus in Moesia. When the battle began, Carinus was killed by his own men. Following Diocletian’s victory, both the Western and the Eastern armies acclaimed him as Emperor.

Emperor Diocletian

Diocletian thought that is almost impossible to rule the empire because of its huge size. He decided that it was too large to be ruled by one person, and eventually, he split the empire into two parts. He didn’t have an heir, so he named an Illyrian officer, who was his son-in-law, named Maximian as Caesar in the west, while Diocletian remained Emperor in the east. This decision afforded Diocletian the time to solve the problems in the East. He still considered himself to be the senior Emperor, leaving the possibility to veto any of Maximian’s decisions.

However, peace in the empire didn’t last for long. As with his predecessors, problems appeared along the Danube River in Moesia and Pannonia. For five years, Diocletian was campaigning throughout the eastern half of the empire. An eventual victory in 286 AD brought peace to the empire and the title of Germanicus Maximus to Diocletian. Also, in 289 AD, Diocletian defeated the Sarmatians and Saracens in 292 AD.

Moreover, Maximian had similar problems in the West. Carausius, the Roman North Sea fleet commander, took control over Britain and part of northern Gaul, proclaiming himself Emperor. He was awarded his command after helping Maximian defeat Bagaudae in Gaul. Later, when it became known that he kept most of the “spoils of war” for himself, he was outlawed, and Maximian issued the death sentence. But, like many people who declared themselves Emperor, he met his death at the hands of someone under his command, in this case, his finance minister Allectus.

Divided empire

The concept of a divided empire obviously worked. However, the situation that every Emperor faced since Augustus had to be corrected, and this was a succession. Diocletian solved this perennial problem with the help of tetrarchy – an idea that preserved the empire in its current state with two emperors but allowed a smooth transition in the event of the death or abdication of the Emperor. The new proposal stipulated that two Augustus – Diocletian in the east and Maximian in the west – and Caesar would serve with each Emperor. This “Caesar” will become the successor of “Augustus” if he dies or resigns. Each of the four would manage its territory and its capital. Although the empire remained divided, each Caesar was accountable to Augustus. Maximian adopted and then named his Praetorian commander Constantius as his Caesar to fill these new posts. Constantius gained a reputation after leading a number of successful campaigns against Carausius. Diocletian chose Caesar Galerius, who served with distinction under the emperors Aurelian and Probe.

Internal Administration

Diocletian’s main achievement was the tetrarchy. Also, the Emperor reorganized the empire from the tax system to the provincial administration. He tried to eliminate revolts in provinces and doubled the number of provinces from 50 to 100 for it. Then, he organized provinces in 12 dioceses ruled by vicars, who gained military responsibilities. The military system was also changed to mobile field forces, the “comitantenses,” and frontier units, the “limitanei.”

Ancient picture of Baths of Diocletian

Because of the influence of Greece and Greek culture, the true center of the empire changed to the East. It became more prominent with the rule of Emperor Constantine, who made Byzantium a “New Rome.” Despite such ambitious projects as the new Roman baths – the largest in the Roman world, built in 305 AD, Diocletian visited the great city only once, and that was before his abdication. Also, Maximian preferred Mediolanum (Milan). For Diocletian, the capital was where he was; however, he eventually chose Nicomedia as his capital.

Read more about the Roman Thermal Baths of Diocletian.

Christians

There were not only financial and border security problems but also the rapid growth of Christianity. Religion was both popular among the poor and the rich. Since Diocletian wanted stability, it led to a return to the more traditional gods of Rome. However, Christianity prevented it. Moreover, since the days of Emperor Augustus, there was an imperial cult – the deification of the Emperor, which Christians and Jews refused to support it.

Diocletian considered himself a living god who wore a jeweled diadem and asked people to kiss the hem of his robe. In 297, the Great Persecution of the Christians started. They refused to sacrifice to the Roman gods. At the same time, in 303, Diocletian ordered the destruction of all churches and Christian texts. Many Christians were tortured and killed until the end of persecution in 305.

Interesting Facts about Diocletian

  1. During Emperor Diocletian’s reign, from 284 to 305, the persecution of Christians reached its peak. Countless Christians were tortured and executed as part of the empire-wide crackdown on the new faith. Only in 305, upon Diocletian’s retirement, the persecution ended.
  2. Diocletian, born in 244, came from humble origins. His parents had a lower social status, making his rise to become the powerful ruler of the Roman Empire even more remarkable.
  3. In 283, Diocletian joined Emperor Carus on a military campaign in Persia. He served as one of the elite cavalry bodyguards known as “protectores domestici,” showcasing his early military prowess and loyalty to the Emperor.
  4. Recognizing the vastness of the Roman Empire, Diocletian implemented a revolutionary administrative system. In 286, he established the concept of the tetrarchy, dividing the empire into two parts governed by himself and his co-emperor, Maximian. Each ruler had a subordinate, Caesar, to assist in the smooth transition of power.
  5. Diocletian’s division of the empire into the Eastern and Western regions proved to be a successful strategy. It brought stability and effective governance, as the empire could be better managed with a focused administration in each region.
  6. Embracing a grandiose self-image, Diocletian considered himself a living god. He adorned himself with a jeweled diadem and demanded that people kiss the hem of his robe as a sign of reverence, highlighting his autocratic rule.
  7. Diocletian initiated extensive reforms to strengthen the empire’s administrative structure. He overhauled the tax system and reorganized provincial governance, bringing increased efficiency and central control to the administration.
  8. The tetrarchy, introduced by Diocletian, aimed to provide stability in the event of the death or abdication of an emperor. This system ensured a smooth transition of power, preventing the chaos that often accompanied succession crises in the past.
  9. Diocletian undertook a significant reorganization of the provinces to quell revolts and maintain control. He doubled the number of provinces, increasing the total from 50 to 100, bolstering the empire’s ability to govern effectively and respond to local uprisings.
  10. The influence of Greek culture played a pivotal role in shifting the empire’s center towards the East. This trend continued with Emperor Constantine, who later founded Constantinople (formerly Byzantium) as the “New Rome,” solidifying the East’s prominence within the empire.

Death of Diocletian

In 303, he became seriously ill after the Emperor’s first trip to Rome. Later, in 305, he left the throne and took retirement in his palace in Spalatum (Split and Croatia today). Moreover, Diocletian persuaded Maximian to leave the throne as well. The joint abdication led to the succession of emperors by Constantinus and Galerius, who were appointed as the new Caesars.

Diocletian died in his palace in 311 AD

Read also about Roman Emperor Vespasian.

Author: Kate Zusmann

Kate Zusmann

I have lived in the Eternal City for the past 12 years. They say every angle of Rome has its history, and I'm here to tell you about the most intriguing historical facts and city legends. :)

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