After the death of Commodus at the end of 192 AD, assassinated following a conspiracy organized by his Praetorian Prefect, Aemilius Laetus, the latter proclaimed Publius Helvius Pertinax as the new emperor. Pertinax, the son of a wealthy freed merchant and at that time a consul alongside the slain emperor, had been chosen for his long political and military career and for his excellent relations with the Senate, from which the imperial office needed to regain legitimacy after the reign of terror imposed by Commodus. However, the Praetorians mainly hoped he would soon distribute among them the riches confiscated from the late emperor and his associates. Yet, faced with severe financial difficulties caused by his predecessor’s extravagance, Pertinax steered his rule toward strict frugality, thereby arousing the resentment of the Praetorian Guard. Furthermore, he decided to pardon those who had been forced to comply with Commodus’s whims in the name of reconciliation.

After an initial failed conspiracy, the most subversive elements of the Praetorian Guard infiltrated the imperial palace at the end of March 193 AD and assassinated the emperor. It was then that Marcus Didius Julianus entered the scene, a politician and career soldier like Pertinax, but far wealthier. This allowed him to purchase the imperial purple, auctioned off by the Praetorians, for 25,000 sesterces. Though his accession was ratified by the Senate, the people disapproved of Julianus for obtaining power in such a dishonorable manner, especially in contrast with the moderation of his predecessor. Most importantly, his elevation was openly rejected by the commanders of the main frontier legions. These leaders revolted against his authority, having themselves proclaimed emperors by their troops: among them, Clodius Albinus in Britain, Septimius Severus in Illyricum and Pannonia, and Pescennius Niger in Syria. It was the prelude to a new civil war.

The closest to Italy was Septimius Severus, who advanced toward the peninsula without major resistance. After losing his fleet in the Adriatic, Julianus attempted to negotiate a joint rule with Severus, but his proposal was rejected. Consequently, he was not only stripped of legitimacy by a Senate fearful of the Severan legions but was ultimately abandoned by his own guard. Julianus had alienated them by ordering the execution of Prefect Laetus, whom he suspected of siding with Severus. In June 193 AD, the Praetorians beheaded him.