Gordian III
Priscus was probably older than Philip, since the latter's political career was pushed by the former's own influence. According to several inscriptions, Priscus was Praefectus of the province of Mesopotamia a frontier province at the border of Persia, therefore highly militarized. He was the Procurator of Macedonia, second in command to Egypt's governor and held judicial responsibilities in Alexandria. Priscus became a member of the Praetorian Guard around 242 during Gordian III Persian campaign, and, when Timesitheus – the praetorian prefect – died in 243, he convinced the young emperor to substitute him with his own brother Philip. For a year, Priscus and Philip served as "de facto" regents of Gordian III.