Domitian was disliked by all the elites, yet he had protected Rome's internal administration and the state's external posture. The Empire faced no existential threats, and was well equipped to deal with any challenges. His murderers and the Senate arranged the succession, which fell to M. Coceius Nerva, an eminent and admired senator, who nonetheless held the throne as a rather weak place-holder. Nerva was advanced in age—66—and had no son, making him unable to start a dynasty of his own. In addition, he was unrelated to any previous ruling dynasty and had no support group in the legions. In this respect his situation was analogous to that of Galba in 68-69. Indeed, when he assumed the purple, some Syrian and Danubian legions moved towards revolt, but were kept in line by a Roman elite desirous of stability. The new Emperor understood his status, though, and was intelligent. He began by giving the legionnaires a pay raise, and then proceeded to bring back the previously exiled senators and cooperated with the Senate as a whole. He also began to blacken Domitian's name.
During his two-year rule, Nerva undertook three popular measures: 1) He created the Alimenta, a small agriculturalists' loan. Small farmers were allowed to borrow funds from the imperial fisc up to 1/12 the value of their landholdings in order to improve their crops or implements. The interest was a low 5%, and the pay-off from the loans went to the local towns and villages. These funds in turn were used to support poorer families and orphans. It was a quite successful measure. 2) In 98, one of the Praetorian Prefects began complaining ominously that no one had prosecuted Domitian's killers. Nerva then calmed the Prefect by doing just that. 3) Most importantly, Nerva took out an insurance policy of sorts, by adopting a son with a strong military reputation. This was Trajan, a legion commander in upper Germany. The adoption was a brilliant move in that it calmed down Rome and removed anxiety about the future. As well, it solved the problem of succession in an extremely popular manner. Nerva's adoption of Trajan was so popular, in fact, it set a trend: several subsequent emperors adopted their successors as son shortly before their deaths. Though the Julio-Claudians had adopted heirs on a few occasions, the practice of adopting powerful men as successors became common practice throughout the second century.
Nerva died in 98. Trajan was on the Rhine and returned to Rome in a leisurely manner. He made a good impression on the capital city elites by entering Rome on foot. He was a significant departure, in that his family was neither from Rome nor Italy. He was from Iberia, and this trend of non-Roman born emperors would expand in the future, indicating a more cosmopolitan era in Roman elite- formation. Trajan was the most famous Emperor in Roman historical memory after Augustus. From a traditionally equestrian lineage, his family only moved into senatorial ranks under Vespasian. The new Emperor had followed the normal elite cursus honorum, but had a penchant for long-term military service, and spent ten years as a military tribune. By the beginning of his rule he was already a rather eminent general. He expressed his military side of himself early on in his Principate: he conquered Dacia for Rome. Supposedly the campaigns against Dacia were undertaken as an effort to restore Roman honor after Domitian's failures, but it is also clear that Trajan wanted a conquest- based military reputation, and wanted the booty that would come from control of this relatively wealthy region. The campaigns may also have been a preventative strike, as the Barbarians of the region had become more popular in the second century CE. To conquer Dacia, it was necessary to cross the Danube and then traverse open country in a forced march. Dacia proper was a fortress surrounded by mountains. In 102 CE, Trajan took an army across the Danube and fought his way into Dacia. Decebalus gave up and became a client king, but the settlement did not last, as the Dacians were not entirely conquered. In 105, Decebalus massacred a Roman garrison in the region and began raiding Moesia again. Thus, in 106 Trajan took thirteen legions into Dacia, ransacked Transylvania, and stormed the Dacian capital. Decbaulus committed suicide, after which the entire area was annexed directly to the Empire. The conquest was extremely profitable in terms of slaves and gold, and the Emperor opened the region up to settlement. Thousands of Latin-speaking peasants settled there, beginning the full-fledged process of Latinization of the region, completed over the next 150 years. It was from this point that the Roman people and aristocracy came to view themselves as world-conquerors par excellence. At the same time, Romans under Trajan received good government. Trajan's methods were as autocratic as Domitian's, but the former sought the advice of the Senate, reported back to it, and socialized with senators. Though he did not at all need senatorial support, this smoothed elite relations in Rome, and the aristocracy quieted down, beginning a trend that was to last for some time, and exempting Emperors from the fear of a senatorial conspiracy. In the process, government became increasingly smooth—imperial legates were professional, the Alimenta was expanded, and Trajan cared for the bankrupt cities which had overspent on public building programs. Imperial curatores were sent to these areas to take over financial responsibility, and to reestablish fiscal soundness. This was a good idea in that the curatores were efficient, but over time, it would cause growing local resentment towards an increasingly obnoxious imperial bureaucracy.
The next decade reinforced the conviction of Roman grandeur, particularly in the East. Since the 50s BCE Rome had been attracted to eastward expansion at Parthia's expense. In the early 100s CE, the Parthian king Chosroes had acted without tact, installing his nephew as king of Armenia and ignoring the arrangement going back to Nero. Furthermore, he had communicated with Decebalus during the Roman-Dacian war. In 113, Trajan slowly moved east, remaining noncommittal in response to Chosroes' peace envoys. In Syria, Trajan retrained the legions, after which he annexed Armenia in 114. 115 saw Roman troops east of the Euphrates, and Trajan took Edessa and marched 150 miles more to Nisibis, annexing mesopotamia in the North and Assyria to the South. In the winter of 115-116, Roman legions built barges and wagons, which they used in the spring to float down the Tigris. The Parthian capital Ctesiphon was then captured and sacked, with Chosroes fleeing and Trajan annexing the area. The Emperor then proceeded to the Persian Gulf. During 116, however, difficulties emerged. The northern Mesopotamian cities began to revolt, and a Parthian army appeared in the South. Trajan was equal to the challenge, however, and maintained realistic advances. By promising the province of Parthia to Chosroes' son Parthamaspates, the Emperor won him over. Parthamaspates fought for Trajan, and won back for him a fair portion of those areas that had rebelled against Rome. Still, persistent difficulties in 116-117 weakened Trajan in terms of manpower and some prestige. Northern Mesopotamia was never fully restored, and a new revolt broke out, this time among the Jewish communities of Cyprus and Egypt. Jewish groups in these areas had expected Trajan not to return West from Parthia, and broke out in opposition to the Hellenistic communities surrounding them. Jewish- Hellenistic animosity had simmered for the past century-and-a-half. In 116, the Jews massacred their Hellenistic neighbors in several areas; in Cyprus in particular they were able to get control of the island and killed up to 250,000 people. In Cyrene, Egypt, the Praetorian Prefect was put under siege. While turning to deal with this in 117, Trajan suddenly had a stroke and died.
At this point, the Praetorian Prefect Plotina stepped forward to attest that Trajan had adopted Hadrian as successor. He was from the same town as Trajan and was of the appropriate aristocratic background. He had completed the proper cursus honorum, had done military service, and had governed two provinces. In 117 he was in Syria, but feeling himself insecure, Hadrain gave a double donative, or accension gift, to his legions. He went back on Trajan's policies in the realm of military expansion: 1) instead of making war on the Sarmatian tribes in the Danube area, he negotiated with them. 2) He opposed the eastern expansion too, and withdrew Roman troops from northern Mesopotamia, returning to Parthian rule the lands east of the Euphrates. This was a reasonable move in that Rome had never been able to convincingly maintain its power there. 3) Hadrian also wanted out of Dacia, but since it had begun the process of Romanization, he was convinced to desist from further withdrawal here. A conspiracy of two generals against him early in his reign illustrated the mounting elite dissatisfaction with such policies.
Hadrian was now at peace with his neighbors, so the question was what to do with his time and the Empire's wealth? He went on a tour, paying particular attention to Greek culture. From 120-123 he visited the western and central provinces, while from 123-125 he looked at the East. In 127 he toured Italy, and then went East again, visiting its great Hellenistic cities, temples, historical markers. He also visited the army camps and would climb mountains just to see the sun rise. He went without a large retinue, however, with little fuss, and impressed the provincials, who had been accustomed to not seeing emperors unless they were passing through on their way to war.