How did Hadrian become Trajan’s successor?

Hadrian’s succession to the throne was a process marked by political maneuvering and his long-standing relationship with the emperor Trajan.

Hadrian’s path to power was supported by influential figures, most notably Trajan’s wife, Plotina, and the powerful advisor Lucius Licinius Sura. Through their favor, Hadrian advanced through a series of traditional senatorial posts, including the consulate in 108. Although his career faced a period of stagnation following Sura's death, he eventually regained Trajan’s confidence.1

By 117, Trajan had entrusted Hadrian with the command of the army in Syria. On August 9, 117, Hadrian received word that Trajan had adopted him, which served as the formal designation of his successor. Following the report of Trajan’s death on August 11, the army proclaimed Hadrian emperor. While some historical accounts have suggested that Plotina may have orchestrated a conspiracy to ensure this outcome, the exact circumstances remain a subject of historical uncertainty.1