Why was Trajan popular with the Roman army?

Trajan was widely regarded as the "soldier-emperor par excellence," earning the deep respect and loyalty of the Roman army through his active leadership and military success.1

His popularity was rooted in several key factors:

• Military Leadership: Unlike many of his predecessors who maintained static frontiers, Trajan was a dynamic commander who personally led his troops in major campaigns. He successfully expanded the empire's borders, most notably by conquering Dacia and conducting extensive military operations against the Parthians in the east.21
• Proven Competence: Before becoming emperor, Trajan was a distinguished soldier and the governor of Upper Germany. His background as an experienced military professional gave him credibility with the legions, who favored a leader with proven tactical expertise.1
• Active Engagement: By consistently engaging in large-scale warfare and territorial expansion, Trajan provided the army with the active, aggressive leadership they valued, contrasting with the more cautious policies of earlier emperors.21

These efforts solidified his reputation as a strong, effective commander, leading to his official designation as Optimus (the Best) by 114 CE.1