Trajan was the son of M. Ulpius Traianus, a prominent senator and general from a famous Roman family. The family had settled in the province of Baetica in Spain sometime toward the end of the Second Punic War, and Trajan himself was just one of many well-known Ulpii in a line that continued long after his own death.
He was born on September 18, 53, in the city of Italica. As a young man, he rose through the ranks of the Roman army, serving in some of the most contentious parts of the empire's frontier, along the Rhine river. He took part in the emperor Domitian's wars against the Germanic peoples, and was known as one of the foremost military commanders of the empire when Domitian was killed in 96.
His renown served him well under Domitian's successor, Nerva, who was unpopular with the army and needed to do something to gain their support. He accomplished this by naming Trajan as his adoptive son and successor in the summer of 97. It was the future emperor Hadrian who brought word to Trajan of his adoption, and thus had Trajan's favor for the rest of his life. When Nerva died on January 27, 98, the highly respected Trajan succeeded without incident.
The new emperor was greeted by the people of Rome with great enthusiasm, which he justified by governing well and without the bloodiness that had marked Domitian's reign. He freed many people who had been unjustly imprisoned by Domitian and returned a great deal of private property which Domitian had confiscated; a process begun by Nerva before his death. His popularity was such that the Roman Senate eventually bestowed upon Trajan the honorific of optimus, meaning "the best".
But it was as a soldier that Trajan is best known to history. In 101, he launched a punitive expedition into the kingdom of Dacia, on the north bank of the Danube River, and forced King Decebalus to submit to him a year later, after Trajan took the Dacian capital Sarmizegetusa. Trajan then returned to Rome in triumph and was granted the title Dacicus Maximus.
However, Decebalus soon began stirring up trouble on the frontier again, trying to get the neighboring kingdoms of the north bank of the Danube to join him. Trajan again took the field, with his engineers building a massive bridge over the Danube, and conquered Dacia completely in 106. Sarmizegetusa was destroyed, Decebalus committed suicide, and on the site of the former capital, Trajan built a new city, Colonia Ulpia Traiana. He resettled Dacia with Romans and annexed it as a province of the Roman empire.
At about the same time, the kingdom of Nabatea expired upon the death of its final king. He willed the realm to Trajan, so at the same time that Dacia was being conquered, the empire gained what became the province of Arabia Petrea (modern southern Jordan and a small part of Saudi Arabia).
For the next seven years, Trajan ruled as a civilian emperor, to the same acclaim as before. It was during this time that he corresponded with Pliny on the subject of how to deal with the Christians, basically telling Pliny to leave them alone unless they were openly practicing the religion. He built several new buildings, monuments and roads in Italy and his native Spain, including a magnificent forum which still stands in Rome today.
In 113, he embarked on his last campaign, provoked by Parthia's decision to put an unacceptable king on the throne of Armenia, a kingdom which the two great empires had shared hegemony over since the time of Nero some 50 years earlier. Trajan marched first on Armenia, deposed the king and annexed it to the Roman empire. Then he turned south into Parthia itself, taking the cities of Babylon, Seleucia and finally the capital of Ctesiphon in 116. He continued southward to the Persian Gulf, whence he declared Mesopotamia a new province of the empire and lamented that he was too old to follow in the steps of Alexander the Great.
But he didn't stop there. Later in 116, he crossed the Khuzestan mountains into Persia and captured the great city of Susa. He deposed the Parthian king Chrosoes and put his own puppet ruler Parthamaspates on the throne. Never again would the Roman empire advance so far to the east.
It was at this point that the fortunes of war--and his own health--betrayed Trajan. The fortress city of Hatra, on the Tigris in his rear, continued to hold out against repeated Roman assaults. The Jews inside the Roman Empire rose up in rebellion, as did the people of Mesopotamia. Trajan was forced to withdraw his army in order to put down the revolts. Trajan saw it as simply a temporary setback, but he was destined never to command an army in the field again.
Late in 116, while resting in the province of Clicia and planning another war against Parthia, Trajan grew ill. His health declined throughout the spring and summer of 117, until he finally died on August 9. On his deathbed, he named Hadrian as his successor. Hadrian, upon becoming ruler, returned Mesopotamia to Parthian rule. However, all the other territories conquered by Trajan were retained.
For the remainder of the history of the Roman Empire and well into the era of the Byzantine Empire, every new emperor after Trajan was honored by the Senate with the prayer felicitor Augusto, melior Traiano, meaning "may he be luckier than Augustus and better than Trajan". Unlike many lauded rulers in history, Trajan's reputation has survived undiminished for nearly 1900 years.
Nerva (96 - 98)
Hadrian (117 - 138)