Emperor Trajan: Optimus Princeps And Builder Of An Empire

While Trajan was lauded as Optimus Princeps, the best of emperors, his reputation was forged in blood and an empire nourished by the spoils of war.

Aug 11, 2020By Kieren Johns, PhD Classics & Ancient History
bust emperor trajan
Bust of Emperor Trajan, 108 AD, via Kunsthistorisches Museum, Vienna (left); with Detail of plaster cast of Trajan’s Column by Monsieur Oudry, 1864, via the Victoria and Albert Museum, London (right)


Amidst the turbulences of imperial politics, the interminable religious debates, and the brutalities of war in the fourth century, the Roman senate occasionally looked back to the halcyon days of an earlier time and a golden age. As part of the inauguration ceremonies for a new emperor, these ancient aristocrats would offer up a telling wish. Collectively, they would salute their new emperor, by offering him some imperial role models: “Sis felicior Augusto, melior Trainao”, or, “Be more fortunate than Augustus, be better than Trajan!” As well as perhaps prompting us to reconsider our interpretation of Augustus, Rome’s first emperor, Trajan cast a long shadow of the history of the Empire: what was it that made him the emperor against whom all others could be judged?


Reigning from AD 98 to 117, the emperor Trajan bridged the first and second centuries and helped usher in a period of almost unparalleled imperial stability, characterized by a great cultural flowering. Nevertheless, the ground from which this culture blossomed was nourished by blood; Trajan was the man who expanded the Empire to its furthest limit.


Domitian, Nerva And The Appointment Of Trajan

portrait bust domitian
Portrait Bust of Domitian, 90 CE, via the Toledo Museum of Art


The story of the emperor Trajan’s rise begins in the Imperial Palace on the Palatine Hill in Rome in September of 96 AD. Rome was then ruled by the emperor Domitian – the youngest son of Emperor Vespasian and brother of the prematurely deceased Titus. Despite the good reputation of both his brother and father, Domitian was not a well-liked emperor, particularly with the senate, whilst he had already had to quash one attempted revolt by Lucius Saturninus, the governor of Germania Superior, in AD 89. Increasingly paranoid, keen to assert the supremacy of his authority, and prone to cruelty, Domitian fell victim to an intricate palace coup. 


By this point, Domitian was so suspicious that he allegedly had the halls of his palace lined with polished phengite stone, to ensure that he could watch his back in the stone’s reflection! Eventually cut down by members of his household staff, the death of Domitian was jubilantly celebrated by the senators in Rome. Pliny the Younger would later provide an evocative description of the joy felt at the condemnation of Domitian’s memory – his damnatio memoriae – as his statues were attacked: “It was a delight to smash those arrogant faces to pieces… No one controlled their joy and long-awaited happiness, when vengeance was taken in beholding his likenesses hacked into mutilated limbs and pieces…” (Panegyricus, 52.4-5)


portrait emperor nerva bust
Portrait of the Emperor Nerva, 96-98 AD, via the J. Paul Getty Museum, Los Angeles

Get the latest articles delivered to your inbox

Sign up to our Free Weekly Newsletter


Others, however, were not so happy to see him go; the urban plebs were indifferent whilst the army, in particular, were less than happy at the loss of their emperor, and as such Domitian’s successor – the elder statesman Nerva, who had been selected by the senate – was put into a precarious position. His political impotence was made clear in the Autumn of AD 97 when he was taken hostage by members of the Praetorian Guard. Although unharmed, his authority was irrevocably damaged. To protect himself he designated Trajan, who was acting as governor in the northern provinces (Pannonia or Germania Superior) and had the support of the Roman army, as his heir and his successor. The era of the adopted emperors had begun. 


A Provincial Princeps

aerial view italica roman spain
Aerial view of the ruins of ancient Italica, Spain, via the Italica Sevilla Website


Born in AD 53, during the final years of the reign of Claudius, Trajan is typically presented as the first provincial Roman Emperor. He was born in the city of Italica, a bustling metropolis in the province of Hispania Baetica (the ruins of the ancient city now lie on the outskirts of modern Seville in Andalucia). However, despite being dismissed by some later historians rather derisively as a provincial (such as Cassius Dio), his family does appear to have had strong Italian links; his father may have come from Umbria, whilst his mother’s family came from the Sabine region in central Italy. Similarly, unlike the comparatively humble origins of Vespasian, Trajan’s stock was considerably higher. His mother, Marcia, was a noblewoman and was actually the sister-in-law of Emperor Titus, whilst his father was a prominent general.


However, much like Vespasian, Trajan’s career was defined by his military roles. In his early career, he served across the empire, including in the frontier provinces in the northeast of the Empire (Germany and Pannonia). It was this military capability and support of the soldiers that prompted Nerva to adopt Trajan as his heir; even if the soldiers didn’t warm to Nerva himself, then they at least would tolerate his successor. In this sense, there is some debate as to whether Nerva chose Trajan, or whether Trajan’s succession was imposed on the elderly emperor; the line between orderly succession and coup appears to be quite blurred here.


The Search For Stability: Senate And Empire

justice of trajan eugene delacroix
The Justice of Trajan by Eugène Delacroix, 1840, via Musée des Beaux-Arts, Rouen


The reign of Nerva could be described as little more than a brief interregnum, reigning for just two brief years between Domitian’s assassination in AD 96 and his own death (aged 67) in AD 98. As such, tensions were still running high upon Trajan’s arrival in Rome as emperor; the blood spilled in the downfall of Domitian had not yet been washed clean. To help mitigate these frictions, Trajan made a conspicuous show of reluctance. He feigned a hesitancy in accepting the emperorship. 


This was, of course, disingenuous; it was rather a social and political performance by the new emperor to indicate that he ruled by the consensus of the Senate, who fulfilled the role of offering and encouraging the new emperor to accept his new role (the reality, of course, was that, as the leader of a considerable armed force, Trajan could do what as wished…). Nevertheless, such carefully contrived performances could backfire: the reign of the emperor Tiberius got off to a rocky start in AD 14 when he displayed similar reluctance to be recognized as Augustus’ successor in AD 14 – his relationship with the Senate never really recovered…  


Imperial Epistles: Emperor Trajan And Pliny The Younger

younger pliny
The Younger Pliny Reproved by Thomas Burke, 1794, via Princeton University Art Museum


Emperor Trajan’s manipulation of senatorial feelings and support was much more successful than some of his predecessors. We know this largely thanks to the literary sources for Trajan and his reign that have survived to us. Perhaps the most well known are the writings of Pliny the Younger. The nephew of Pliny the Elder, the author, and naturalist who, despite his long and distinguished life, is most well known for his death during the eruption of Mount Vesuvius. Indeed, we know so much about the man thanks in part to his nephew! The younger Pliny wrote two letters, also known as Epistles, that detail the death of his uncle during the eruption; he wrote them for his friend, the historian Tacitus, giving a timely reminder of the cultural communities that existed in the Roman Empire.


eruption vesuvius
The Eruption of Vesuvius by Pierre-Jacques Volaire, 1771, via Art Institute of Chicago


Pliny also had a close relationship with Trajan. He was responsible for delivering a panegyric, a praise-filled oration, for the emperor upon his accession in AD 100. This document preserves telling insight into how the emperor wished to be understood, particularly by the senate. Pliny’s panegyric is most emphatic in presenting the contrast between Trajan and Domitian. A series of Pliny’s other Epistles also record his communication with the emperor whilst he was serving as governor of the province of Bithynia (modern Turkey). These provide a fascinating insight into the administrative functions of the Empire, including his query to the emperor about how best to deal with a troublesome religion: the Christians.


Empire Builder: The Conquest Of Dacia

scene roman soldiers severed dacian enemy
Scene of Roman soldiers holding the severed heads of Dacian enemies to the emperor Trajan, from a cast of Trajan’s Column, via the Museum of Natural History, Bucharest


Perhaps the defining event of emperor Trajan’s reign was his conquest of the Dacian kingdom (modern Romania), which was completed over two campaigns in AD 101-102 and 105-106. The Trajanic conquest of this region was ostensibly launched to remove the threat posed to the imperial frontiers by the Dacian threat. Indeed, Domitian had previously suffered a rather embarrassing reverse against the Dacian forces led by their King Decebalus. Trajan’s first campaign compelled the Dacians to come to terms but did little to bring lasting peace to the region. Decebalus’ attacks on Roman garrisons in the region in AD 105 led to the Roman siege and destruction of Sarmizegetusa, the Dacian capital, as well as the death of Decebalus, who took his own life rather than be captured. Dacia was annexed to the empire as a particularly wealthy province (contributing an estimated 700 million denarii per year, in part thanks to its gold mines). The province became an important defensive outpost within the Empire, bolstered by the natural boundary of the great Danube river. 


trajan column rome
View of Trajan’s Column in Rome, erected in 106-13 AD, via National Geographic


Trajan’s Dacian campaigns are so well-known thanks largely to the permanent reminder of his conquest erected in Rome. Today, visitors can still look up at the colossal edifice of Trajan’s Column in the center of Rome. Running vertically up this columnar monument, a narrative frieze depicts the emperor’s Dacian campaigns, using public art and architecture as the medium for bringing the action – and often emotion – of Rome’s wars home to the people. The column’s frieze is rich in iconic scenes, ranging from the personification of the Danube watching over the embarkation of the Roman forces at the start of the campaign, through to Decebalus’ suicide as the Roman soldiers close in on the defeated king. Quite how Trajan’s contemporaries were meant to view all of these scenes – the frieze runs to around 200m up a column that stands around 30m high – remains a subject much debated by historians and archaeologists.

Parthia: A Final Frontier


bronze sestertius trajan
Bronze Sestertius of Trajan, with reverse depiction showing Parthian King, Parthamaspates, kneeling before the emperor, 114-17 AD, via the American Numismatic Society


Dacia was not the limits of Trajan’s ambition as an imperial conqueror. In AD 113 he turned his attention to the southeastern edges of the empire. His invasion of the Parthian Kingdom (modern Iran) was prompted ostensibly by Roman outrage at the Parthian’s choice of King of Armenia; this border region had been under Parthian and Roman influence since the reign of Nero in the mid-first century. However, Trajan’s reluctance to accept Parthian diplomatic entreaties suggests that his motivations were rather more suspect. 


cuirass statue emperor trajan
Cuirass Statue of Emperor Trajan, after AD 103, via Harvard Art Museum, Cambridge


Sources for the events of Trajan’s Parthian campaign are fragmentary at best. The campaign began by an eastern assault on Armenia which resulted in the annexation of the territory in AD 114. The following year, Trajan and the Roman forces marched southwards into northern Mesopotamia, conquering the Parthian capital city of Ctesiphon. However, complete conquest was not achieved; insurrections erupted across the Empire, including a large Jewish revolt (the second Jewish rebellion, the first had been quashed by Vespasian and his son, Titus). With military forces needing to be re-deployed, and the failure to take Hatra, another important Parthian city, Trajan installed a client king before retreating to Syria. 


Trajan’s plans for the conquest of the east appear to have been cut short. Cassius Dio, in his early 3rd-century history, records Trajan’s lament. Looking out from the Persian Gulf across the sea towards India, the Emperor is reported to have mourned that his advancing years meant he would be unable to follow in the footsteps of Alexander the Great in marching further eastwards. The romanticized exploits of the Macedonian King cast a long shadow over the Roman Emperors throughout history… Nevertheless, by marching into Armenia and annexing northern Mesopotamia – as well as subjugating Dacia – Trajan would be remembered as Rome’s greatest conquering emperor.


Imperial Capital: Trajan And The City Of Rome

trajan forum basilica aureus

Gold Aureus of Trajan with reverse view of Basilica Ulpia in the Forum of Trajan, 112-17 AD, via the British Museum, London


Trajan’s reign was a period characterized by a number of incredible architectural achievements, across the empire and within the imperial capital itself. Many of these were directly related to the processes of imperial conquest. Indeed, perhaps the greatest of Trajan’s structures – overseen by the great architect, Apollodorus of Damascus – was the bridge over the Danube built-in AD 105. Built to facilitate the emperor’s conquest of Dacia, and then to serve as a reminder of Roman mastery, the bridge is believed to have been the longest arch bridge in span and length for over a millennium. The bridge features prominently on the frieze of Trajan’s column, on which Roman construction activities are a recurrent motif, a representation of empire building in the literal sense.



bronze dupondius trajan
Bronze Dupondius of Trajan with reverse image of an arched bridge, 103-111 AD, via the American Numismatic Society


Likewise, the power of emperor Trajan was writ large across the urban fabric of Rome itself, with a range of ideologically significant structures. Not only were Trajan’s structures pointedly political in emphasizing his power, but they also helped to communicate his commitment to the people of the empire. He gave to Rome a set of opulent thermae, or baths, on the Oppian Hill. In the heart of the city, sandwiched between the Roman Forum and the Forum of Augustus, Trajan cleared a significant portion of land to create the Mercatus Traiani (the Markets of Trajan) and the Forum of Trajan, which is the site of the Column of Trajan. The emperor’s new forum dominated the urban center of Rome and remained a potent reminder of Trajan’s power for centuries afterward. The 4th-century historian Ammianus Marcellinus recorded the visit of Constantius II to Rome in AD 357, describing the Forum, and particularly the equestrian statue of Trajan in the center of the great square and  Basilica Ulpia within, as “a construction unique under the heavens.” 


A Golden Age? Death Of Trajan And The Adoptive Emperors

portrait bust trajan
Portrait bust of Trajan, 108-17 AD, via the British Museum, London


Emperor Trajan died in AD 117. The health of Rome’s greatest conquering emperor had been worsening for some time, and he finally succumbed to the city of Selinus in Cilicia (modern Turkey). That the city was to be henceforth known as Trajanopolis is a clear testament to the reputation the emperor had secured for himself. He was deified by the Senate in Rome, and his ashes were laid to rest under the great Column in his forum. Trajan and his wife Plotina had had no children (indeed, Trajan was reputedly much more inclined towards homosexual relationships). However, he ensured the smooth succession of power by naming his cousin, Hadrian, as his heir (the role of Plotina in this succession remains a subject of historical controversy…). By adopting Hadrian, Trajan ushered in a period that is typically classified as a golden age; the whims of dynastic succession – and the danger of a megalomaniac such as Caligula or Nero taking power – were reduced. Instead, the emperors would ‘adopt’ the best man for the role, blending dynastic pretensions with meritocracy.


column of trajan
View of the Column of Trajan with the Santissimo Nome di Maria al Foro Traiano (Church of the Most Holy Name of Mary) in the background by Giovanni Piranesi, before 1757, via the Brandenburg Museum, Berlin


Today, a rich vein of scholarship seeks to understand the emperor. Although some later historians would challenge his exemplary reputation, with some – such as Edward Gibbon – questioning his pursuit of military glory. The speed with which Hadrian would give up some of Trajan’s territorial acquisitions and set the limits of the empire – most famously at Hadrian’s Wall in northern Britain – was a testament to this. Nevertheless, there can be no doubt as to the fondness with which the reign of Trajan – the Optimus Princeps, or best of emperors – was remembered by the Romans themselves.

Author Image

By Kieren JohnsPhD Classics & Ancient HistoryKieren is a UK based contributing writer with a PhD in Classics and Ancient History. His thesis explored the representation and status of the Severan emperors. He is passionate about sharing his interest in the past with as many people as possible. Away from his research, Kieren is also interested in arts, literature, and travel.