Publius Julius Geminius Marcianus

Marcianus was a native of Cirta in North Africa. Debrowa considers that he "was probably the first representative of his family in the Roman senate", making him a novus homo.[2] Professor Edward Champlin included him as a member of "a Cirtan community at Rome" he infers existed there, whose members included: Quintus Lollius Urbicus, consul in either 135 or 136; Gaius Arrius Antoninus, consul c. 170; and the rhetorician Fronto. Champlin speculates Marcianus may be the "Marcianus noster" who assisted Fronto in his prosecution of Herodes Atticus.[3]

The beginning of his senatorial career was not impressive. As a member of the vigintiviri, a preliminary and required first step toward gaining entry into the Roman Senate, Marcianus was allocated to the tresviri capitalis, which was not a prestigious office. Following this he held the typical series of offices: a hitch as military tribune in Legio IV Scythica, then another hitch as military tribune in Legio X Fretensis. He returned to Rome to serve as quaestor, then plebeian tribune, praetor, legate to the proconsul of Africa, and legate or commander of Legio X Gemina.[2]

The outbreak of the Roman–Parthian War of 161–166 provided Marcianus with the opportunity to show his abilities. He was commissioned as commander of a collection of vexillations from Pannonia that was sent to the Parthian front, and showed he was successful as legate of Legio X Gemina. He was promoted to govern the imperial province of Roman Arabia, then returned to be appointed consul.[2]

Shortly after his consulship, Marcianus was appointed proconsular governor of Macedonia. This is unusual, since Macedonia was considered a province whose administration was allocated to senators before they achieved the consulship. Dabrowa explains this oddity "because of the danger of Marcomanni and Germans attacking the province was really serious."[2] The last office Marcianus is known to have held is the proconsular governorship of Asia around 182.