Reform of Praetorian Guards

Once Septimius Severus became emperor in 193CE, Severus discharged the Praetorian Guard, who had murdered previous emperor Pertinax and auctioned the Roman Empire to Didius Julianus.
Its members were stripped of their ceremonial armor and forbidden to come within 160 kilometers (99 mi) miles of the city on the pain of death.
Severus replaced the old guard with 10 new cohorts recruited from veterans of his Danubian legions.
He garrisoned Legio II Parthica at Albanum, only 20 kilometers (12 mi) from Rome.
Severus was the first Roman emperor to station some of the imperial army in Italy. He realized that Rome needed a military central reserve with the capability to be sent anywhere.

Bigger & Wealthier Army

Around 197CE he increased the number of legions from 30 to 33, with the introduction of the three new legions: I, II and III Parthica.
He gave his soldiers a donative of a thousand sesterces (250 denarii) each, and raised the annual wage for a soldier in the legions from 300 to 400 denarii.