How did Septimius Severus turn Rome into a military monarchy?

Septimius Severus transformed the Roman government into a military monarchy by centering his authority on the army rather than constitutional sanction. Recognizing that his power relied on military might, he implemented several key reforms to secure the loyalty of his troops and consolidate his control:1

• Military Reorganization: He replaced the existing Praetorian Guard with a new 15,000-man force recruited from his own loyal Danubian legions. He also increased the size of the praetorian cohorts and installed a new legion, the Second Parthica, near Rome.12
• Soldier Incentives: To ensure support, he significantly increased military pay—raising the base rate from 300 to 500 denarii—and granted soldiers the right to marry, a privilege previously denied to them.21
• Career Advancement: He opened new horizons for noncommissioned officers, allowing them to attain the tribunate and enter the equestrian order, effectively making the army a seedbed for social advancement.2
• Administrative Shifts: He marginalized the Senate, favoring the equestrian order for government appointments and recruiting officials from provincial and peasant backgrounds. Additionally, he placed Italian courts under the control of the praetorian prefect, further diminishing senatorial influence.21