Julianus had a promising political career, governing several provinces, including Dalmatia and Germania Inferior, and defeated the Chauci and Chatti, two invading Germanic tribes.

Septimius Severus, commander of the legions in Pannonia and the nearest of the generals to Rome, marched on the capital, gathering support along the way and routing cohorts of the Praetorian Guard Julianus sent to meet him.

[12] After repelling an invasion by the Chauci,[12] a tribe dwelling in the drainage basin of the river Weser, the northwestern coastal area of present-day Germany, he was raised to the consulship in 175 along with Pertinax.

[16] Modern historians generally consider this a demotion for political reasons, as Commodus, the Roman Emperor at the time, feared Julianus' growing power.

[20] Titus Flavius Claudius Sulpicianus, prefect of Rome and Pertinax's father-in-law, who was in the Praetorian camp ostensibly to calm the troops, began making offers for the throne.

[27] Pertinax had increased the silver content of the denarius to 87%, whereas Didius Julianus ordered it reduced to 75%, nearly the adulterated amount that was present during the reign of Commodus.

[30] When news of the public anger in Rome spread across the Empire, three influential generals, Pescennius Niger in Syria, Septimius Severus in Pannonia, and Clodius Albinus in Britain, each able to muster three legions, rebelled.

After seizing the ringleaders and killing them, the soldiers reported what they had done to Marcus Silius Messala, the consul, who summoned the senate to inform them of the proceedings.

[43] The Senate passed a motion proclaiming Severus emperor, awarded divine honours to Pertinax, and sentenced Julianus to death.

From arguably the reign of M. Aurelius, Rome would be constantly subject to incursions from the descendants of these tribes (see Crisis of the Third Century and Migration Period).

The trend he started, which would continue under the Severan dynasty on a far larger scale, destroyed confidence in Rome's currency, led to rampant hyperinflation, and caused widespread economic upheaval.

[51] In the movie The Fall of The Roman Empire, Julianus is played by Eric Porter and depicted as a scheming henchman of Commodus.

At the end of the movie, Julianus and Pescennius Niger, played by Douglas Wilmer, another crony of Commodus, compete against each other in the auction for the throne of Rome.