How did the Emperor Trajan change the Roman Empire?

A bust of Trajan

Emperor Trajan (53-117 AD) has traditionally been regarded as one of the greatest Roman Emperors (ruled from 98 to 117 AD), but modern historians have argued that his legacy was mixed. Trajan's reign led to both positive impacts on the Roman Empire. While Trajan's foreign invasion of Dacia, Arabia, and Mesopotamia created real benefit to the Empire, Parthia's conquest was ephemeral and wasteful.

On the domestic side, Trajan was a dynamic administrator, and he did much to reverse some of the abuses that had developed under previous Emperors such as Domitian. Additionally, his domestic policies helped to improve the socio-economic condition in Italy. While Rome benefitted from many of his conquests and policies, Parthia's invasion almost led to disaster, and his gains were short-lived. After Trajan's death, Hadrian was forced to abandon Parthia.

How did Trajan become the Roman Emperor?

A relief showing a battle between Romans and Dacians

Trajan’s reign (98-117 AD) occurred at perhaps one of the greatest eras in Roman History. In the First Century A.D., the economy of Rome had been expanding for many years, and the Empire continued to expand. The period witnessed a cultural renaissance, and many of the great Latin writers wrote their greatest works. Successive Emperors maintained the system that was perfected by Augustus, which was an imperial system that shared power with the Senatorial elite. This system had provided stability to a large part of Europe and the Near East. Marcus Ulpius Traianus was born in what is now modern Spain and was of Italian descent.[1]

His father was a general and governor and was later enrolled in the Senate. Trajan grew up in Rome, and he served with his father in Syria, and he later enjoyed the favor of Emperor Domitian. In 91 AD, he served as consul.[2] In 96 AD, Domitian was assassinated in a conspiracy, and Nerva ascended the throne. Trajan was governor of Lower Germany and was in command of several legions, and was an essential power broker in the years after Domitian's death. Nerva, who was advanced in years, adopted him as his son and heir.[3]

When did Emperor Trajan become an Emperor?

Petra the capital of the Nabatean Kingdom, today

In 98 AD, Trajan became Emperor after the death of Nerva. Trajan proved to be an energetic ruler and immediately reduced the influence of the Praetorian Guard.[4] He secured support by offering donations to the legions and the population of Rome and reduced taxes.

After a series of civil wars that had weakened the Empire, Trajan helped finance many public structures and ordered many aqueducts. He also prohibited wasteful expenditure on festivals. Trajan also initiated a series of social welfare reforms.

What did Trajan do as Emperor?

Trajan successfully overhauled the administration of the Empire and ended abuses by Senators. His domestic policy achievements are impressive, but his main focus was always on military glory. He abandoned the policy of Augustus of not seeking to expand the Empire.[5] Only Britain was added to the Empire since the First Emperor's death. Trajan was determined to expand Rome’s borders, and for the first time in a century, he pursued an active policy of conquest.

In modern Romania, a powerful confederation of Thracian tribes, the Dacians had proven a formidable foe and had defeated Roman governors in the past. After careful preparations, Trajan invaded Dacia and, in 101-102, reduced the Dacian kingdom to vassal status. However, in 105, the Dacians revolted, and Trajan invaded the area and, in a series of bloody campaigns, ended the revolt with the capture of the capital Sarmizegethusa (106 AD). Dacian resistance was ended with the suicide of their king and chief priest, Decalbus. Trajan organized the kingdom into a Roman Province, and he encouraged settlers from all over the Empire to settle in the new territory.[6] Trajan was a restless figure, and he seems to have sought to emulate the achievements of Alexander the Great and Julius Caesar.[7]

He recruited a large army for the invasion of Parthia, the Romans' greatest enemy. First, he annexed the Nabatean Kingdom with its famous capital of Petra to secure his flank. The Parthian campaign began in 105/106 AD, and it took place when a series of civil wars had weakened that Empire. Despite its problems, the Parthians defended their territories fiercely. They even placed a puppet on the throne of Armenia in 110 AD.[8]

Trajan launched a ferocious counter-attack, recaptured Armenia, and later conquered Northern Mesopotamia (modern North Iraq) and organized it. He built a road to link the province to the rest of the Empire, and this allowed his legions to strike deep into the heart of the Parthian Empire. In 115, he marched his army down the Tigris River, and he swiftly captured the Parthian summer capital of Ctesiphon and advanced down the Tigris to the Persian Gulf.[9]

He annexed the entire area of modern Iraq and incorporated it into the Empire. An anecdote is told that when Trajan saw the Persian Gulf, he wept because he was too old to conquer the rest of the known world. In 116, while in Antioch, the Emperor nearly died in an earthquake, and a series of revolts broke out across the Roman territories in the east.[10] A severe Jewish revolt broke out in several eastern Mediterranean areas. Trajan was ill and old and decided to journey back to Rome, but he died in 116 AD, in Asia Minor. The Emperor had no children and adopted Hadrian, an experienced soldier, and governor. After Trajan’s death, Hadrian became ruler of the Roman World.

Why did Trajan want Rome to conquer Dacia?

Dacia's conquest, a powerful military force in the Balkans and a real rival of Rome was a significant achievement. The Dacians had been a problem for the Romans since the time of Julius Caesar. However, no Roman Emperor had been effectively able to contain them. Trajan's conquest from a military point of view was remarkable as the kingdom consisted of fortified settlements in a mountainous region.[11] It has often been argued that Domitian helped weaken the Dacians before the conquest in 106 AD. The addition of the old Dacian kingdom to the Empire initially strengthened Rome. The gold mines of the area boosted the economy, as did the new lands that were acquired.

The annexation of the kingdom strengthened the Danube frontier and secured the Balkans for decades. However, many argue that the conquest of Dacia was ultimately a drain on the Empire. Moreover, over time as the Roman legions weakened, it proved difficult to defend. In the crisis of the 3rd century, the province was abandoned to the Goths and other tribes.[12] However, the territory had remained part of the Empire for 150 years, and at least in the first century of Roman rule it brought the empire new revenues and was a bulwark against barbarian incursions.

Why did Trajan's invasion of the Parthian Empire almost fail?

There had been no serious efforts to conquer large areas of the Parthian Empire since the time of Mark Anthony. Trajan wanted to conquer all or at least part of the Empire. However, it was a vast, sprawling, and diverse polity, and the Romans could never have absorbed it even with their vast resources and capabilities. Trajan had been accused of megalomania because of his ambitions in the east. Despite his capture of Ctesiphon and the annexation of the Parthian Empire's western sections, the Romans never really controlled the majority of the new territories. The campaign in the East overstrained the resources of the Romans. It left the legions in Mesopotamia isolated, and they were on the point of being cut-off when Trajan died.

Furthermore, Parthia's efforts left many areas poorly guarded, which led to Jewish revolts that destabilized the eastern provinces. Roman did not have any meaningful control over this region. Trajan’s campaign fundamentally weakened the Empire in the east. Hadrian was forced to conquer these lands to stave off a complete collapse in the east.

In the longer term, some of the conquests of the Emperor strengthened the Roman East. Dacia's conqueror added two provinces in the east, the Nabatean Kingdom (modern Jordan) and northern Mesopotamia (Northern Iraq). These provinces greatly added to the Empire's revenues and strengthened the Roman strategic position in the region. The province of Mesopotamia meant that Rome could keep Parthia on the defensive. Roman supremacy was not challenged for over a century in the Ancient Near East.

Trajan’s Column in Rome

How did Trajan change the domestic policies of Rome?

The Roman Empire was at its zenith during the reign of Trajan. However, he, like the Senate members, was worried about the relative decline of Italy. It had not prospered as much as the other Imperial territories. Italy's population was falling, and many were worried about the reduced number of Italians who were serving in the legions.[13]

Trajan used much of the booty from his conquests on public works in the Italian cities such as Rome. This was to boost the urban economies and encourage the landed aristocracy to spend more time in cities. Trajan also ordered Senators from the provinces to own land in Italy. This ensured that the Senatorial elite, irrespective of their origin, had links with Rome and Italy. Trajan also introduced the alimieta. This was a charitable scheme. It was a variety of subsidies to local communities.[14] It involved the regular distribution of money to only the Italian communities. It helped improve the lives of poor Italians, and the alimieta even reduced the number of infanticide instances.

Trajan developed this policy to strengthen Italy and the core of the Empire. This ensured that Italians remained preeminent in the Roman Empire. The Emperor’s policy was at least partially successful because it arrested the decline in Italy. It was adopted by later Emperors.[15] Trajan has been criticized for his many wars, especially for his devaluation of the coinage. This is believed to set a dangerous precedent for later Emperors; however, Trajan left his successor Hadrian with a healthy treasury, and the economy was well-managed during his reign.

Trajan was an able administrator and, unlike his predecessors, respected the constitution and Rome's laws. Trajan enacted some laws that improved the status of slaves, and it became illegal for masters to abandon old slaves. He forbade the use of informers, and there were no treason trials during his years in power. Trajan did not rule as an autocrat like so many of his predecessors.[16] It has been stated that he gave the Empire its longest period of stability and good government in its history.[17]

Was Trajan a Good Emperor?

Trajan has been acclaimed as a great Emperor, but he was also an egomaniac who loved war. Ultimately his actions seriously undermined the Empire. The truth is that Trajan had many achievements but also some glaring failures. His conquest expanded the Empire and generated new revenues for Rome, and improved its strategic position concerning its enemies.

However, his adventures in Parthia were costly and could have ended in disaster. Most of his gains were lost during Hadrian's reign. Trajan’s domestic policy had some successes, such as his efforts to strengthen Italy and his reform of the penal code concerning slaves. His administration of the Empire was excellent, and the economy thrived under him. Trajan can be regarded as a great Emperor and justifies the acclaim that he received from his fellow Romans in the centuries after his death.

Suggested Reading

Alston, Richard Aspects of Roman History 31BC-AD117 (Abingdon: Routledge, 2014)

Luttwak, Edward N. The Grand Strategy of the Roman Empire: From the First Century A.D. to the Third. Baltimore: Johns Hopkins University Press, 1979)

Isaac, B. The Limits of Empire, The Roman Army in the East, Revised Edition (Oxford University Press, 1990)

Stadter, Philip A., and Luc Van der Stockt, eds. Sage and emperor: Plutarch, Greek intellectuals, and Roman power in Trajan (98-117 AD). Vol. 29. Leuven University Press, 2002.


  1. Bennett, Julian. Trajan. Optimus Princeps. (Bloomington, Indiana University Press, 2001), p. 18
  2. Bennet, p. 34
  3. Bennet, p 46
  4. Mommsen, Theodor A History of Rome Under the Emperors (London: Routledge, 1999), p 113
  5. Suetonius, Life of Augustus, xxv
  6. Schmitz, Michael The Dacian Threat, 101–106 AD. Armidale, Australia: Caeros Pty, 2005), p 134
  7. Cassius Dio, Roman History, book 68, xi
  8. Bennet, p 101
  9. Cassius Dio, 68, 17
  10. Cassius Dio, 10, 19
  11. Cassius Dio, 10, 23
  12. Bennet, p 189
  13. Alston, Richard Aspects of Roman History 31BC-AD117 (Abingdon, Routledge, 2014),p. 115
  14. Alston, p. 118
  15. Bennet, p 119
  16. Pliny the Younger, Letter 10. 68
  17. Bennet, p. 10

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