The Roman Empire certainly had its ups and downs when it comes to emperors. Some lasted mere months and others for decades. During times of peace emperors would often rule for longer periods of time, even more so when serving as part of a greater dynasty of emperors. One of the most prosperous and stable periods of the Roman Empire was a time during the Five Good Emperors, also known as the Nerva-Antonine dynasty. This dynasty lasted almost a century, from 96-180. What's most curious is that this incredibly successful line of emperors always adopted prospective heirs rather than choosing their own children, the peace and prosperity only came to an end when the last Good Emperor, Marcus Aurelius, chose his son Commodus as his heir.
This is a look at the top 10 longest reigning Roman Emperors. It should be noted that this is for the emperors of the unified Roman Empire (27 BC – 476 AD). Following this date the empire broke up into separate western and eastern halves.
10. Marcus Aurelius - 19 years, 10 days
The last of the Five Good Emperors. Marcus Aurelius was the adoptive heir of Antoninus Pius. He was chosen to rule alongside his adoptive brother Lucius Verus. The two complimented each other well. Marcus was an excellent administrator and perfect emperor to govern the empire, whereas Verus was better suited to commanding Rome's forces in various campaigns.
Their joint ruled was successful until Verus died in 169, leaving Marcus alone as the sole emperor. Following the loss, Marcus appointed his son Commodus as his heir. He tried to tutor Commodus in statecraft and philosophy in an attempt to mould him into a capable heir, but it was no use, Commodus had no interest in these things.
Much of Marcus' reign was marred with the Marcomannic Wars on the northern frontier. Despite devoting much of his attention and resources to these wars they were never resolved. After Marcus' death in 180 Commodus became sole emperor (after co-ruling since 177). Marcus would be remembered for his Stoic philosophical outlook and thoughts, much of which were compiled and can be read in his Meditations. Marcus Aurelius reigned for just over 19 years.
9. Caracalla - 19 years, 2 months
Caracalla was the son of Septimius Severus, and thus part of the Severan dynasty of emperors which ruled from 193 and 235 (although not throughout that entire period). Caracalla was appointed as his father's co-Augustus, or co-emperor, in 198 at the age of 10. During his early reign he served in a number of official roles alongside his younger brother Geta, whom he despised – although it is unclear exactly why. This division only worsened when Severus died and Caracalla and Geta inherited the entire Roman Empire. They even considered splitting the empire in two to make their lives easier. Eventually their hatred of one another boiled over and in 211 Geta was murdered by Praetorian Guards, likely on the orders of Caracalla, leaving the him as the sole ruling emperor.
Some time later in 217 Caracalla met his end due to a self-fulfilling prophecy. It came about as a result of the Praetorian Prefect Macrinus hearing that he was destined to kill Caracalla and take the throne. Fearing that Caracalla would hear this and have him killed, Macrinus persuaded a soldier who had been refused promotion to kill him, thus ending over 19 years of rule. Macrinus did in fact become the next emperor.
8. Trajan - 19 years, 7 months
Trajan was the second of the five good emperors, having been adopted by Nerva and chosen as his successor. Prior to his accession to the throne Trajan had proved himself a capable military commander. Indeed, when he took power he expanded the empire to its greatest extent in 117. Trajan devoted much time to improving public works, such as roads and buildings, as well as commissioning a host of new projects. The peace across the empire allowed Trajan to even introduce the alimenta, a scheme by which poor and orphaned children could get a good education, cheaper food and monetary handouts by the government. It is said Trajan could walk the streets of Rome without a bodyguard as he was so loved by the people.
In 117, upon returning from a campaign in the east Trajan fell ill and died shortly after, ending a rule of 19 years and 7 months. He named his adoptive son Hadrian as his successor.
7. Diocletian - 20 years, 5 months
Diocletian is best known today for forming the Tetrarchy, or rule of four. He is responsible for bringing order to the Roman Empire following the chaos of the Crisis of the Third Century. He realised that one emperor could not rule such a vast expanse of territory with varying cultures and enemies on all sides. He appointed another co-emperor and then two junior Caesars who would then eventually replace the emperors upon death or retirement.
Diocletian did indeed see a long and relatively stable rule of over 20 years, before he retired in 305. Unfortunately those who succeeded him were not as committed to the Tetrarchy, and Diocletian lived to see Rome descend into civil war once more as the new emperors fought for dominion over the entire Roman Empire. Diocletian would eventually die at his retirement palace in Dalmatia.
6. Hadrian - 20 years, 11 months
Hadrian was another member of the Five Good Emperors. He was adopted as the heir to Trajan and ascended to the throne in 117. During his reign he undertook many provincial tours across the empire. While in Britain he commissioned the eponymous Hadrian's Wall to be built in order to clearly mark the territories of Roman Britain and the barbarian controlled Caledonia to the north.
While touring the east he became particularly fond of Greece and returned there many times. While in Greece he formed the Panhellenion, a league that united the Greek states. He remained here until he was called off to war in Judaea in 132 as a result of the Jewish people not wanted to have their monotheistic religion absorbed into the Roman pantheon.
Hadrian returned to Rome following the war, which he regretted greatly as he had wanted to avoid bloodshed throughout his reign. In 138 Hadrian died after naming Antoninus Pius as his successor. Hadrian's rule was just one month short of 21 years.
5. Tiberius - 22 years, 6 months
Tiberius hails from the early days of the Roman Empire, being appointed as the successor to Augustus himself. Initially Tiberius ruled carefully and wisely, steadily expanding Rome's frontier and filling up the city's treasury.
In his later years he became uninterested in the politics of Rome and retired to the island of Capri, rarely making trips back to the city despite still being emperor. During this time, much of the running of Rome fell to the Praetorian Prefect Sejanus. His influence grew the longer Tiberius was absent, and he even started to erect statues of himself across the city, and he started to rule with an iron fist. When reports of this reached Tiberius, he had Sejanus executed.
Tiberius was largely disliked by the populace now, and as a result he became bitter and ruthless. After returning to Capri, Tiberius pondered on his choice of successor, now a very old man by the standards of the ancient world, he had outlived most of his family. He eventually settled on Caligula, who was still young had not yet displayed the full extent of his madness. Tiberius died at the age of 78 in the year 37 after 22 years and 6 months of rule.
4. Antoninus Pius - 22 years, 6 months, 28 days
Antoninus Pius was yet another member of the Five Good Emperors, who all had lengthy reigns. Antoninus was appointed as the successor to Hadrian after displaying the qualities of a great and fair administrator. Indeed he was, introducing a number of legal and financial reforms, while also greatly expanding and improving the infrastructure across the empire. One of his many projects was to build the Antonine Wall, just north of Hadrian's Wall.
The reign of Antoninus saw virtually no conflict at all, rather than looking to conquer new lands he instead focused on raising up existing provinces and territories. This truly was a time of Pax Romana, or 'Roman Peace'.
Towards the end of his life his health started to fail, and he had given most of his duties over to Marcus Aurelius, his successor – who would prove to be an incredibly capable one at that. In 138 Antoninus died at his Villa Lorium at the age of 74. His reign beats that of Tiberius by 28 days.
3. Constantius II - 24 years, 5 months, 12 days
The third-born son of Constantine the Great, Constantius II inherited the Roman Empire alongside his two brothers when his father died. Constantius ruled the eastern half of the empire, while his brothers took the West and Southern sections.
Constantius saw much conflict during his reign, with many usurpers and pretenders to the throne. By 350 both of his brothers were dead, and he now had to put down rebellions across the western half of the empire, which he succeeded in doing by 353. This left Constantius as the sole ruler of the entire Roman Empire.
The stability was short-lived, and by 355 more usurps had sprung up across the empire. While journeying to battle one of these usurpers, Julian, Constantius fell ill with a fever and died. His reign of over 24 years was ended, and so was the Constantinian dynasty.
2. Constantine - 30 years, 9 months, 27 days
Constantine I, or Constantine the Great, had to fight off many foes before eventually becoming the sole Emperor of Rome. He was born during the Crisis of the Third Century and lived through Diocletian's Tetrarchy, which his father was part of. His main rivals during his quest to become sole Emperor were Maximian, Maxentius, Galerius and Licinius, all of which were eventually defeated.
However, he will always be remembered for one thing in particular – his role in forever changing religion in Ancient Rome. Before Constantine the Roman Empire had persecuted Christianity, seeing it as an affront to the traditional Gods and beliefs. Monotheism had no place in Rome, or so most of Constantine's predecessors had thought.
Some argue Constantine was never a Christian, instead just using the opportunity of religious unrest to win support and seize power. Regardless of his personal views, Constantine legalised Christianity across the Roman Empire and ended all persecution, as stated in the Edict of Milan in 313. Following this, Christianity would forever be the dominant religion in the Roman Empire.
Constantine eventually died in 337 after over 30 years of rule. He left the Roman Empire to his three sons, Constantine II, Constantius II and Constans.
1. Augustus - 40 years, 7 months
Augustus, originally known as Octavian, was the first Roman Emperor. The great-nephew of Julius Caesar, Augustus fought for dominion over Rome in the final years of the republic against Mark Antony. Emerging victorious he ended over a century of civil war and unrest declaring himself 'Princeps', or 'First Person'. He never actually took the title of emperor, instead acting as a reluctant chief administrator for the Roman Empire only acting for the good of Rome.
Upon taking the mantle of leadership Augustus used his own vast personal fortune to fund many public works such as restoration of temples and public buildings as well as the construction of roads that webbed their way across the empire. Augustus slowly obtained more power over his rule until eventually reaching the level of control and authority that his successors would hold – all the while feigning reluctance.
In his later years the elderly Augustus was troubled by thoughts over who would succeed him. Many of his chosen relatives had passed away in unsuspecting circumstances, leaving him few choices left. Eventually he settled on Tiberius, the son of his wife, Livia.
Augustus died at the age of 75 in the year 14 ending a staggering 40 years of rule. He had successfully ended the civil wars and turmoil of the Roman Republic and founded what would later be known as the Julio-Claudian dynasty of emperors who would rule long after him. In his own words, Augustus had found Rome made of clay and left her made of marble.