The Roman Tetrarchy: An Attempt to Stabilize Rome

The Roman Tetrarchy refers to a system of governance established by the Roman Emperor Diocletian that marked a significant reorganization of the Roman Empire’s political structure and was intended to address the challenges of governing such a vast and diverse territory.

Under the Tetrarchy, the Roman Empire was divided into two parts: the Western Roman Empire and the Eastern Roman Empire. Each of these halves was then further divided into two regions, with each region being ruled by a separate ruler.

While the Tetrarchy itself did not endure in the long term, its innovations and reforms left a lasting legacy on the Roman Empire’s political, administrative, and ideological landscape. The attempt to address the empire’s challenges through a more structured and collaborative approach foreshadowed changes that would continue to shape the history of the Roman world and its successor states.

What is the Roman Tetrarchy? 

Starting with the basics, the word Tetrarchy means “rule of four” and refers to the division of an organization or government into four parts. Each of these parts has a different ruler.

Although there have been multiple Tetrachies over the centuries, normally we refer to the Tetrarchy of Diocletian when the word is used. Still, another well-known Tetrarchy that was not Roman is called The Herodian Tetrarchy, or the Tetrarchy of Judea. This group was formed in 4 BCE, in the Herodian kingdom and after the death of Herod the Great.

In the Roman Tetrarchy, there was a division into the Western and Eastern empires. Each of these divisions would have its own subordinate divisions. The two main halves of the empire were then ruled by one Augustus and one Caesar, so in total there were four emperors. The Caesars were, however, subordinate to the Augusti.

Why Was the Roman Tetrarchy Created?

The history of the Roman Empire and its leaders was a bit wobbly, to say the least. Especially in the years leading up to the reign of Diocletian, there were many different Roman emperors. In a time span of 35 years, an astonishing total of 16 emperors seized power. That is about a new emperor every two years! Clearly, this isn’t very helpful for creating consensus and a common vision within the empire.

Having a quick overturn in emperors wasn’t the only problem. Also, it was not uncommon that some parts of the empire didn’t recognize certain emperors, leading to division and various civil wars between groups. The Eastern part of the empire contained the largest and wealthiest cities. This part of the empire was historically far more eclectic and open to competing philosophies, religious ideas, or just thoughts in general when compared to its Western counterpart. Many groups and people in the Western part didn’t share this common interest and how it shaped the policy within the Roman Empire. Therefore, fights and assassinations were not uncommon. Assassination attempts towards the reigning emperor were rampant and often successful, creating political chaos. Continuous fights and assassinations made it virtually impossible to unite the empire under these circumstances. The implementation of the Tetrarchy was an attempt to overcome this and establish unity within the empire.

What Problem Did the Tetrarchy Try to Solve?

One might wonder, how can a division of the empire actually create unity? The main asset of the Tetrarchy was that it could rely on different people who were believed to have the same vision for the empire. By enlarging the empire´s civil and military services and reorganizing the empire´s provincial divisions, the largest bureaucratic government in the history of the Roman empire was established.

READ MORE: The Roman Army

Through reforming the empire alongside a common vision, revolts, and attacks could be better monitored. Because they could be better monitored, opposers of the emperors had to be very careful and thoughtful if they wanted to overthrow the government. One attack or assassination wouldn´t do the job: you need to kill at least three more Tetrachs in order to gain absolute power.

Administrative Centers and Taxation

Rome remained the most important prefect of the Roman Empire. Yet, it was no longer the only active administrative capital. The Tetrarchy allowed for newly formed capitals to serve as defensive headquarters against outside threats.

These new administrative centers were located strategically, close to the empire’s borders. All capitals were reporting to the Augustus of that particular half of the empire. Although officially he had the same power as Maximian, Diocletian styled himself an autocrat and was the de facto ruler. The whole political structure was his idea and continued to develop in his manner. Being an autocrat, thus, basically meant that he elevated himself above the empire´s masses He developed new forms of architecture and ceremonies, through which new plans surrounding city planning and political reforms could be imposed on the masses.

Bureaucratic and military growth, rigorous and continuous campaigning, and construction projects increased the state´s expenditures and brought a vast amount of tax reforms. This also means that from 297 CE onwards, imperial taxation was standardized and made more equitable across every Roman province.

Who Were Important Persons in the Roman Tetrarchy?

So, Diocletian was the emperor of ancient Rome from 284 to 305 CE. He was born in the province of Dalmatia and decided to join the military, as so many did. As part of the military, Diocletian rose through the ranks and eventually became the primary cavalry commander of the entire Roman Empire. Up until then, he had spent most of his life in military camps preparing for fights with the Persians.

READ MORE: The Roman Cavalry

After the death of Emperor Carus, Diocletian was proclaimed the new emperor. While in power, he ran into a problem, namely that he did not enjoy the same prestige across the empire. Only in the parts where his army was fully dominant could he exercise his power. The rest of the empire was obedient to Carinus, a temporary emperor with a dreadful reputation.

Diocletian and Carinus have a long history of civil wars, but eventually in 285 CE Diocletian became master of the entire empire. When in power, Diocletian reorganized the empire and its provincial divisions, establishing the largest and most bureaucratic government in the history of the Roman Empire.

READ MORE: Roman Wars

So it can be said that Diocletian had quite a trouble with coming into absolute power. Maintaining power was also quite the objective. History had shown that any successful army general could, and would, claim the throne.

The unification of the empire and the creation of a common objective and vision were also conceived as a problem. Actually, this had been a problem that was going on for a couple of decades. Because of these struggles, Diocletian decided to create an empire with multiple leaders: the Roman Tetrarchy.

The Roman Tetrarchy was divided into the Western and Eastern empires. When the leadership of the empire was split up according to this in 286 CE, Diocletian continued to rule the Eastern empire. Maximian was proclaimed as his equal and co-emperor of the Western empire. Indeed, they could both be deemed the Augustus of their part.

In order to secure a stable government after their deaths, the two emperors decided in 293 CE to name additional leaders. This way, a smooth transition from one government to the other could be realized. The people that would become their successors first became Caesars, thus still being subordinate to the two Augusti. In the East this was Galerius. In the West, Constantius was Caesar. Although sometimes the Caesars were also referred to as emperors, Augustus was always the highest power.

The aim was that Constantius and Galerius remained Augusti long after the death of Diocletian and would pass on the torch to the next emperors. You could see it as if there were senior emperors who, while alive, picked their junior emperors. Just like in many contemporary businesses, as long as you provide consistency and quality of work the junior emperor could be promoted to senior emperor at any given time.

The Success and Demise of the Roman Tetrarchy

By already taking into account who would replace them after their death, the emperors played a rather strategic game. It meant that the policy that was implemented would live on long after their death, at least to some degree.

During Diocletian’s life, the Tetrarchy functioned very well. Both Augusti were actually so convinced of the qualities of their successors that the senior emperors jointly abdicated at one point, passing on the torch to Galerius and Constantius. A retired emperor Diocletian could peacefully sit out the rest of his life. During their reign, Galerius and Constantius named two new Caesars: Severus and Maximinus Daia.

The Demise of the Tetrarchy

Unfortunately, the successor Augustus Constantius died in 306 CE, whereafter the system broke down rather quickly and the empire fell into a series of wars. Galerius promoted Severus to Augustus while Constantius’ son was proclaimed by his father´s troops. However, not everyone agreed on that. Especially the sons of current and former Augusti felt left out. Without making it too complicated, at one point there were four claimants to the rank of Augustus and just one to that of Caesar.

Although many efforts were put into the re-establishment of just two Augusti, the Tetrarchy never again achieved the same stability as was seen under the reign of Diocletian. Eventually, the Roman Empire moved away from the system that was introduced by Diocletian and returned to placing all the power in the hands of one person. Again, a new chapter in Roman history emerged, bringing us one of the most important emperors that the Roman Empire has known: Constantine.

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