Diocletian was not the only challenger to Carinus ' rule: the usurper M. Aurelius Julianus, Carinus ' corrector Venetiae, took control of northern Italy and Pannonia after Diocletian's accession.

The officers were killed and Julianus ' head was sent back to the emperor.

Flavius Claudius Julianus, born in May or June 332 or 331 in Constantinople, was the son of Julius Constantius ( consul in 335 ), half brother of Emperor Constantine I, and his second wife, Basilina, a woman of Greek origin.

His maternal grandfather was Julius Julianus, praetorian prefect of the East under emperor Licinius from 315 to 324 and consul after 325.

Pertinax's successor in Rome was Didius Julianus, who had bought the emperorship in an auction.

Julianus was condemned to death by the Senate and killed, and Severus took possession of Rome without opposition.

Commodus took the loss of Saoterus badly, and Perennis now seized the chance to advance himself by implicating Paternus in a second conspiracy, one apparently led by Publius Salvius Julianus, who was the son of the jurist Salvius Julianus and was betrothed to Paternus's daughter.

Didius Julianus, the future emperor, a relative of Salvius Julianus, was dismissed from the governorship of Germania Inferior.

For instance, Caracalla's maternal grandfather was Julius Bassianus, but Caracalla's cognomen was not Julianus, but rather Bassianus as well.

It was at this time that Valentinian fell ill and a battle for succession broke out between Severus, a representative of the army, and Rusticus Julianus, magister memoriae and a representative of the Gallic nobility.

His election caused considerable surprise, and it is suggested by Ammianus Marcellinus that he was wrongly identified with another Jovianus, chief notary ( primicerius notariorum ), whose name also had been put forward, or that during the acclamations the soldiers mistook the name Jovianus for Julianus, and imagined that the latter had recovered from his illness.

He claimed the imperial throne in response to the murder of Pertinax and the elevation of Didius Julianus, but was defeated by a rival claimant, Septimius Severus and killed while attempting to flee from Antioch.

He was still serving in Syria when news came through firstly of the murder of Pertinax, followed by the auctioning off of the imperial title to Didius Julianus.

Niger was a well regarded public figure in Rome and soon a popular demonstration against Didius Julianus broke out, during which the citizens called out for Niger to come to Rome and claim the imperial title for himself.

Although imperial propaganda issued on behalf of Septimius Severus later claimed that Niger was the first to rebel against Didius Julianus, it was Severus who beat Niger to it, claiming the imperial title on April 9.

Upon his death he was succeeded by Didius Julianus, whose reign was similarly short.

Didius Julianus (; 30 January 133 or 2 February 137 – 1 June 193 ), was Roman Emperor for three months during the year 193.

Julianus was ousted and sentenced to death by his successor, Septimius Severus.

The Roman Emperor Didius Julianus was buried by the fifth milestone on the Via Labicana, after being executed in 193.

* The Praetor's Edict is definitively codifed by Salvius Julianus on Hadrian's orders.

* 542-Julian ( or Julianus ) from Constantinople begins evangelizing Nubia, accompanied by an Egyptian named Theodore

The praetorian guards auctioned off the imperial position, which Senator Didius Julianus won and became the new Emperor, an act which triggered a brief civil war over the succession, won later in the same year by Septimius Severus.

Didius Julianus was raised by Domitia Lucilla, mother of Roman Emperor Marcus Aurelius.

Titus Flavius Claudius Sulpicianus, prefect of the city, father-in-law of the murdered emperor, being at that moment in the camp to which he had been sent to calm the troops, began making offers, when Julianus, having been roused from a banquet by his wife and daughter, arrived in all haste, and being unable to gain admission, stood before the gate, and with a loud voice competed for the prize.

The guards immediately closed with the offer of Julianus, threw open the gates, saluted him by the name of Commodus, and proclaimed him emperor.

Julianus was deserted by all except one of the prefects and his son-in-law, Repentinus.

Julianus was killed in the palace by a soldier in the third month of his reign ( 1 June 193 ).

When Didius Julianus was put to death by order of the Senate, who dreaded the power of Septimius Severus, the latter turned his arms against Pescennius Niger.

* 173 campaign against the Chauci of Gallia Belgica, commanded by governor Didius Julianus

Didius Julianus, after becoming emperor by winning an auction the Praetorian Guard held for the title, experienced difficulty in garnering support even within the ranks of his own troops and, in a desperate attempt to save himself, asked Pompeianus to be co-regent with him, but this offer too was declined.

As a result, the same year, Julianus ben Sabar led a pro-Samaritan revolt, and by 530 had captured most of Samaria, destroying churches and killing the priests and officials.

All Christian sects were officially tolerated by Julianus, persecution of heretics was forbidden, and non-Christian religions were encouraged, some Christians even being compelled to make restitution for pagan property stolen or destroyed.

Caesarius was highly influenced by his teacher, Julianus Pomerius.

Eventually Sulpicianus promised 20, 000 sesterces to every soldier ; Julianus, fearing that Sulpicianus would gain the throne, then offered 25, 000.

As Niger began bolstering his support in the eastern provinces, Severus marched on Rome which he entered in early June 193 after Julianus had been murdered.

The old-established Praetorian Guard was based at the Castra Praetoria in Rome, and had frequently proved disloyal, making and deposing emperors and even on one occasion in 193 putting the Imperial throne up for auction to the highest bidder ( cf: Didius Julianus ).

The consular Didius Julianus was installed by Pertinax's murderers, and was himself murdered on June 1 by a partisan of the rebellious governor of Pannonia Superior, Septimius Severus ( see below ).

It depicts the tale of Roderick, the last Visigoth king of Spain, and his general Julianus, based on the legendary Julian, count of Ceuta.

As a consequence, it is alleged that Julianus dispatched a centurion to the east with orders to assassinate Niger at Antioch.

* June 1 – Septimius Severus enters the capital and has Julianus put to death.

When news of the public anger in Rome spread across the Empire, the generals Pescennius Niger in Syria, Septimius Severus in Pannonia, and Clodius Albinus in Britain, each having three legions under his command, refused to recognize the authority of Julianus.

After the short reigns of Pertinax and Didius Julianus, Septimius Severus becomes emperor.

In the civil war of 193, this legion supported Septimius Severus and helped him defeat his opponents first Pertinax and Didius Julianus, then Pescennius Niger and Clodius Albinus.

Septimius Severus commanded the Pannonian legions, and led them successfully against Didius Julianus near Rome in 193, and defeated Pescennius Niger in 194.

# Public Sale of the Empire to Didius Julianus by the Praetorian Guards – Clodius Albinus in Britain, Pescennius Niger in Syria, and Septimius Severus in Pannonia, declare against the Murderers of Pertinax – Civil Wars and Victory of Severus Over his Three Rivals – Relaxation of Discipline – New Maxims of Government

The new self-proclaimed Emperor in Rome, Didius Julianus, had to face the commander of the Pannonian legions, Septimius Severus.