afterwards named M.DidiusCommodusSeverusJulianus, the successor of Pertinax, was the son of Petronius Didius Severus and Clara Aemilia, the grandson or great-grandson of Salvius Julianus, so celebrated as a jurisconsult under Hadrian. Educated by Domitia Lucilla, the mother of M. Aurelius, by her interest he was appointed at a very early age to the vigintivirate, the first step towards public distinction. He then held in succession the offices of quaestor, aedile, and praetor, was nominated first to the command of a legion in Germany, afterwards to the government of Belgica, and in recompense for his skill and gallantry in repressing an insurrection among the Chauci, a tribe dwelling on the Elbe, was raised to the consulship. He further distinguished himself in a campaign against the Catti, ruled Dalmatia and Lower Germany, and was placed at the head of the commissariat in Italy. About this period he was charged with having conspired against the life of Commodus, but had the good fortune to be acquitted, and to witness the punishment of his accuser. Bithynia was next consigned to his charge; he was consul for the second time in A. D. 179, along with Pertinax, whom he succeeded in the proconsulate of Africa, from whence he was recalled to Rome and chosen praefectus vigilum.

Upon the death of Pertinax, the Praetorian assassins publicly announced that they would bestow the purple on the man who would pay the highest price. Flavius Sulpicianus, praefect of the city, father-in-law of the murdered emperor, being at that moment in the camp, to which he had been despatched for the purpose of soothing the troops, proceeded at once to make liberal proposals, 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 contended for the prize. The bidding went on briskly for a while, the soldiers reporting by turns to each of the two competitors, the one within the fortifications, the other outside the rampart, the sum tendered by his rival. At length, Sulpicianus having promised a donative of twenty thousand sesterces a head, the throne was about to be knocked down to him, when Julianus, no longer adding a small amount, shouted that he would give twenty-five thousand. The guards thereupon closed with the offers of Julianus, threw open their gates, saluted him by the name of Commodus, and proclaimed him emperor. The senate was compelled to ratify the election. But the populace, after the first confusion had subsided, did not tamely submit to the dishonour brought upon the state. Whenever the prince appeared in public he was saluted with groans, imprecations, and shouts of "robber and parricide." The mob endeavoured to obstruct his progress to the Capitol, and even ventured to assail him with stones. This state of public feeling having become known, Pescennius Niger in Syria, Septimius Severus in Illyria, and Clodius Albinus in Britain, each having three legions under his command, refused to acknowledge the authority of Julianus, who for a time made vigorous efforts to maintain his power. Severus, the nearest and therefore most dangerous foe, was declared a public enemy; deputies were sent from the senate to persuade the soldiers to abandon him; a new general was nominated to supersede him, and a centurion despatched to take his life. The praetorians, long strangers to active military operations, were marched into the Campus Martius, regularly drilled, and exercised in the construction of fortifications and field works. Severus, however, having secured Albinus by declaring him Caesar, advanced steadily towards the city, made himself master of the fleet at Ravenna, defeated Tullius Crispinus, the praetorian praefect, who had been sent forward to arrest his progress, and gained over to his party the ambassadors commissioned to seduce his troops. On the other hand, the praetorians, destitute of discipline, and sunk in debauchery and sloth, were alike incapable of offering any effectual resistance to an invader, and indisposed to submit to restraint. Matters being in this desperate state, Julianus now attempted negotiation, and offered to share the empire with his rival. But Severus turned a deaf ear to these overtures, and still pressed forwards, all Italy declaring for him as he advanced. At last the praetorians, having received assurances that they should suffer no punishment, provided they would give up the actual murderers of Pertinax and offer no resistance, suddenly seized upon the ringleaders of the late conspiracy, and reported what they had done to Silius Messala, the consul, by whom the senate was hastily summoned and informed of these proceedings. Forthwith a formal decree was passed proclaiming Severus emperor, awarding divine honours to Pertinax, and denouncing death to Julianus, who, deserted by all except one of his praefects and his son-in-law, Repentinus, was slain in the palace by a common soldier in the 61st year of his age and the third month of his reign.

Niebuhr, in his lectures on Roman history published by Dr. Schmitz, treats the common account that, after the death of Pertinax, the praetorians offered the imperial dignity for sale to the highest bidder, as a sad exaggeration or misrepresentation, and declares, that he is unable to believe that Sulpicianus and Julianus bid against one another, as at an auction. With all respect for his opinion, no event in ancient history rests upon surer evidence. Setting aside the testimony of Herodian, Capitolinus, and Spartianus, we have given the narrative of that strange exhibition almost in the words of Dio Cassius, who was not only in Rome at the period in question, but actually attended the meeting of the senate held on the very night when the bargain was concluded. We cannot suppose that he was ignorant of the real facts of the case. We cannot imagine any motive which could induce him to fabricate a circumstantial and improbable falsehood.