Top 10 Groundbreaking Facts about Diocletian

More than 150 emperors reigned the Roman Empire until the Western Empire collapsed. Augustus Caesar was the first Roman emperor in 27 B.C. and the last was Romulus Augustulus, who reigned until 476 AD. 

Many Roman emperors contributed to the amazing progress and expansion of the state. But some others, such as Caligula and Nero, only brought abuse, fear, and chaos.

One thing about the Roman Empire that amazes everyone is how the Empire lasted for so long. If you have read Roman history, you may know how anyone could rise the social ladder. Roman people could make their fate with their ability and wit.

The man who is featured in this article has proved this fact. It is Emperor Diocletian who was one of the intellectual and creative Roman emperors. Let’s learn more about him. 

10. Diocletian abdicated from the throne voluntarily.

Diocletian - The Roman Emperor
Diocletian – The Roman Emperor

Diocletian was one of few Roman emperors who resigned from the throne voluntarily. After a trip to Rome in 303, Diocletian fell ill seriously and decided to retire from power. 

He abdicated the throne in 305 A.D. After that, he started living his retired life in his huge palace fortress in Spalatum. This huge walled complex featured reception rooms, a temple, and colonnaded streets. Besides, it also included a mausoleum, a bathhouse, and extended gardens. 

Diocletian also advised Maximian to take retirement from power. This joint retirement transited Constantius and Galerius to be new emperors. 

After retirement, Diocletian would spend his time in the garden raising cabbages. Later, he died in October of 311 A.D.

After the death of Diocletian, a tetrarchy collapsed. War after war between successors brought the Roman Empire back to turmoil. It stopped when Constantine the Great came into power, nearly two decades later, in 324. 

The bureaucratic system developed under Diocletian was Diocletian’s successful legacy. It helped the Empire run smoothly for at least 150 years.

9. Diocletian hated Christians and prosecuted them mercilessly. 

An image of Persecution during Diocletian's reign
An image of Persecution during Diocletian’s reign

One thing that troubled Diocletian was the continuing growth of Christianity. The Christians also had been a headache in Rome since the time of Nero.

Emperor Nero blamed Christians for the Great Fire of Rome in 64 A.D. He ordered Christians’ persecution throughout the Empire. 

Diocletian wanted stability and the establishment of the traditional Roman gods completely. So he had to stop Christians or had to compel them to accept Roman gods.

Besides, Diolectian’s ego enlarged the problem, the staying of Christians in Rome. Diocletian considered himself a living god. He wanted people to prostrate themselves before him and kiss his robe’s hem.

Diocletian also introduced “Diocletianic” or “Great Persecution,” that limited Christians’ rights. Either Christians had to accept the religious practices of the Romans or had to die. Diocletian ordered his army to destroy all churches and Christian texts in 303 A.D.

This bloody persecution came to an end between 303 and 312. As a result, Diocletian failed in his mission to eradicate Christians. Like Nero, many Roman emperors tried to end Christianity. But it became the most preferred religion after 324 A.D.

8. Diocletian constructed the largest baths of Ancient Rome.

Baths of Diocletian.
Baths of Diocletian

Diocletian had a co-emperor, Maximian, who equally shared the empire rule. But Diocletian always considered himself superior. Because of this attitude, he didn’t worry about imposing a heavy tax on Roman inhabitants. 

He spent taxpayer’s money on the infrastructure and military of the Roman Empire. In 297, Diocletian raised the Imperial tax. It made it easier for the emperor to raise funds for national expenditure. 

Also, it helped Diocletian construct the Baths of Diocletian. It was one of the biggest projects for Diocletian at the time.

The Baths of Diocletian were constructed between 298 and 306 A.D. These Roman baths were the largest of their kind ever constructed in ancient Rome. People believed that the complex had occupied 13 hectares (32 acres). Also, it could accommodate up to 3,000 people at any time. Later, the facades of the ancient entertainment complex went under reconstruction. 

The 16th-century church, Santa Maria Degli Angeli e dei Martiri, is an integrated form of this ancient structure. Michelangelo was a designer of this 16th-century church. 

7. Diocletian issued the “Edict on Maximum Prices” in 301 A.D.

One of the four pieces of the Edict
One of the four pieces of the Edict

Empire’s finance always had an important consideration for Roman emperors. They heavily fund the army to strengthen national security and for the war. 

Also, Diocletian needed more money to invest in the provincial reorganization. The next campaign was to expand military power. For this, Diocletian tried to improve the coinage with better quality pieces. 

Diocletian’s experiment on coinage ended up lowering the metal quantity. When these coins lost intrinsic worth, Diocletian needed to issue “Edict on Coinage.” The state was suffering inflation. This mandate from Diocletian helped the state clear previous debts.

Still, Diocletian needed to improve the financial state of the Empire. So, he ordered officers for a new census to determine how many inhabitants lived in the Empire. 

Also, the census was to be confirmed of how much land they owned and what that land could produce. Diocletian issued “Edict on Maximum Prices” in 301 A.D to raise funds for the Empire and end inflation.

He increased taxes and revised the collection process through this proclamation. Those who had a family business, compelled to continue whether they made a profit or loss. 

6. Diocletian succeeded in establishing peace in the East in 299 A.D.


The Sassanid Empire of Persia was big trouble for the Roman Empire at the time. It was the final Empire until the Muslim Conquest existed in the 7th century. 

Roman emperors fought several wars against the Empire of Persia. Diocletian also countered a similar warfare affair against Persia. He had to fight against Persia when Narseh became King of the Persians in 294. 

Narseh was nice with the Romans until he declared war against the Roman Empire in the year 295. First, he invaded western Armenia and then Roman Mesopotamia, where he defeated Galerius. 

After this defeat, Diocletian rebuked Galerius publicly. Galerius then took revenge, winning two battles against Narseh. He finally captured Narseh’s camp, his treasury, his harem, and his wife.

When Narseh got the news, he sent a peace proposal to the Roman emperor. He wanted to get his wife and children through peace negotiations. The negotiation resulted in returning Armenia to the Romans. Romans then got control over the five satrapies between the Tigris and Armenia. 

5. Diocletian had installed a bureaucratic government system in Roman Empire.

The bust of Diocletian
The bust of Diocletian

Diocletian managed the tetrarchy lasted longer through the bureaucratic government. He enlarged the Empire’s civil and military services. He did it by creating provincial divisions and reorganized administrative centers widely. It was the most bureaucratic government in the history of the Empire. 

New administrative centers emerged in Nicomedia, Mediolanum, Sirmium, and Trevorum. It helped Diocletian turn the Roman Empire into an effective autocracy. 

This bureaucratic government also enabled Diocletian to make important decisions for the Empire. 

The bureaucratic government continued doing well during Diocletian’s reign. But it collapsed when Maxentius and Constantine came into power. They were the sons of Maximian and Constantius, respectively. 

4. Diocletian founded the tetrarchy to end the crisis of the third century. 

The Tetrarchy instituted by Diocletian
The Tetrarchy instituted by Diocletian

The Empire divided between Diocletian and Maximian continued smoothly. Then, Diocletian realized the barrier of succession. Diocletian then founded tetrarchy to this aged-old problem. 

Tetrarchy was an idea that could preserve the Empire in its present state, with two emperors. It also allowed a smooth transition if an emperor died or surrendered. 

Diocletian and Maximian then started searching for two Caesars. They needed two Caesars who could serve under each emperor. Now each of the four could have their territory and capital. The Empire would remain split, and each Caesar needed to answer to each emperor or both Augusti. 

While selecting, Maximian appointed his praetorian commander Constantius as his Caesar. Maximian chose Constantius as Constantius had already led several successful campaigns against Carausius. 

Likewise, Diocletian adopted Galerius as his Caesar in the East. Galerius had gained popularity by serving with distinction under Emperors Aurelian and Probus.

3. Diocletian split the Roman Empire into two for complete control. 

Map of the Roman diocese
Map of Roman diocese

Diocletian already knew that the problem of reigning the Empire was immense size. Also, he learned that a single emperor couldn’t rule the entire Empire. So Diocletian split the entire into two parts, East and West. Then, he started searching for a co-emperor. 

As Diocletian didn’t have his heir, he made his son-in-law, Maximian. Maximian was an Illyrian officer, Caesar in the West. Roman sovereigns often took titles such as “Augustus,” “Caesar,” and “Imperator” to stress their importance. 

Maximian, new Caesar, was promoted to Augustus a year later. He was honored with the name Marcus Aurelius Valerius. Finding a co-emperor, Diocletian managed a time to deal with the problems in the East. 

But still, both emperors felt the lack of peace in the Empire. Soon, Diocletian found a problem with his predecessors along the Danube River in Moesia. 

Then, Diocletian campaigned for the next five years throughout the East. He finally got a victory in 286 A.D. The concept of dividing the Empire worked but still needed improvement.

2. Diocletian became emperor in his forties.

A coin with the image of Diocletian
A coin with the image of Diocletian

Emperor Diocletian took a long time to reach the Roman throne. Early, he served in the Roman army and rose quickly through the ranks. 

History has not much shown what position Diocletian held or what he did in the army. His name was recorded for the first time in an official document in the year 282 A.D. 

Historians believed that Diocletian was a member of an elite corps in the Illyrian army. He was unknown until 283 AD. Then, he earned the position of commander of the Protectores domestici. It was an elite cavalry force directly attached to the Imperial household. 

Later, Diocletian served as a part of “protectores domesticis” or imperial bodyguard. He continued this position under Carus’ successor and son Numerian. He also participated in a Persian campaign during which Emperor Carus died mysteriously.

After Carus’ death, his two sons, Carinus and Numerian, became co-emperor. Carinus reigned in the West, and Numerian captured the East. But Numerian died mysteriously in the closed coach he traveled in. He was found dead when he returned from the Eastern border of the Roman Empire. 

When Aper, the general, knew the news of Numerian’s death, he shared the news with the army. Then, the legion (group of the army) declared Diocletian emperor of the East. Later, Diocletian accepted it in 284 A.D. However, he hadn’t become the emperor of the entire Roman Empire yet. 

Carinus was a weak and unpopular ruler in Roman Empire. He also mistreated the Senate and seduced his officers’ wives. And when the Battle of the Margus began, Carinus was killed by his own army. This incident let Diocletian control the entire Roman Empire. 

1. Diocletian wasn’t born to the Roman Imperial family.

Diocletian's family tree
Diocletian’s family tree

Diocletian was one of the Roman emperors who were outsiders to an Imperial family. He was born on 22 December 243–245 A.D. (the exact date is unknown) in the Roman province of Dalmatia. 

If Dalmatia existed in the modern-day world, it would encompass several territories. It would include Croatia, Bosnia and Herzegovina, Montenegro, Kosovo, and Serbia. Also, Diocletian’s birth was the ancient Roman city of Salona. Salona was situated right next to Split. At that time, Split was the second-largest city in the Dalmatia region.

Diocletian’s birth name had a Greek origin as either “Diocles” or “Diocles Valerius.” He belonged to a family of low status in Dalmatia, so he tried very hard to secure the Roman throne. 

Besides, the details about Diocletian’s childhood and parents haven’t been mentioned much. It is because the details of forty years earlier aren’t available in the history book. 


Every detail about Diocletian is full of importance. But the transition from unknown to the Roman emperor is quite fascinating. It is motivating that someone born in a lower-class family suddenly rises to be the Roman emperor. It is the most surprising part of the above for me. Do you agree with me, or have you found other facts also interesting? Write your thoughts in the comment below.

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