Trajan was Roman Emperor

Roman Emperor

The Roman emperor was the ruler of the Roman State during the imperial period . The Romans had no single term for the office although at any given time, a given title was associated with the emperor...

 from 98 to 117 AD. Born into a non-patrician family in the province of Hispania Baetica

Hispania Baetica

Hispania Baetica was one of three Imperial Roman provinces in Hispania, . Hispania Baetica was bordered to the west by Lusitania, and to the northeast by Hispania Tarraconensis. Baetica was part of Al-Andalus under the Moors in the 8th century and approximately corresponds to modern Andalucia...

, in Spain

Spain

Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 Trajan rose to prominence during the reign of emperor Domitian

Domitian

Domitian was Roman Emperor from 81 to 96. Domitian was the third and last emperor of the Flavian dynasty.Domitian's youth and early career were largely spent in the shadow of his brother Titus, who gained military renown during the First Jewish-Roman War...

. Serving as a legatus legionis

Legatus legionis

Legatus legionis was a title awarded to legion commanders in Ancient Rome.-History:By the time of the Roman Republic, the term legatus delegated authority...

 in Hispania Tarraconensis

Hispania Tarraconensis

Hispania Tarraconensis was one of three Roman provinces in Hispania. It encompassed much of the Mediterranean coast of Spain along with the central plateau. Southern Spain, the region now called Andalusia, was the province of Hispania Baetica...

, in Spain

Spain

Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

, in 89 Trajan supported the emperor against a revolt on the Rhine led by Antonius Saturninus

Lucius Antonius Saturninus

Lucius Antonius Saturninus was the Roman governor of the province Germania Superior during the reign of the Emperor Domitian. In the spring of 89, motivated by a personal grudge against the Emperor, he led a rebellion known as the Revolt of Saturninus, involving the legions Legio XIV Gemina and...

. In September 96, Domitian was succeeded by Marcus Cocceius Nerva

Nerva

Nerva , was Roman Emperor from 96 to 98. Nerva became Emperor at the age of sixty-five, after a lifetime of imperial service under Nero and the rulers of the Flavian dynasty. Under Nero, he was a member of the imperial entourage and played a vital part in exposing the Pisonian conspiracy of 65...

, an old and childless senator who proved to be unpopular with the army.