In his government Niger acquired the esteem of the soldiers and the love of the provincials. His rigid discipline foritfied the valor and confirmed the obedience of the former, whilst the voluptuous Syrians were less delighted with the mild firmness of his administration, than with the affability of his manners, and the apparent pleasure with which he attended their frequent and pompous festivals. As soon as the intelligence of the atrocious murder of Pertinax had reached Antioch, the wishes of Asia invited Niger to assume the Imperial purple and revenge his death. The legions of the eastern frontier embraced his cause; the opulent but unarmed provinces, from the frontiers of Æthiopia to the Hadriatic, cheerfully submitted to his power; and the kings beyond the Tigris and the Euphrates congratulated his election, and offered him their homage and services. The mind of Niger was not capable of receiving this sudden tide of fortune: he flattered himself that his accession would be undisturbed by competition and unstained by civil blood; and whilst he enjoyed the vain pomp of triumph, he neglected to secure the means of victory. Instead of entering into an effectual negotiation with the powerful armies of the West, whose resolution might decide, or at least must balance, the mighty contest; instead of advancing without delay towards Rome and Italy, where his presence was impatiently expected, Niger trifled away in the luxury of Antioch those irretrievable moments which were diligently improved by the decisive activity of Severus.

The country of Pannonia and Dalmatia, which occupied the space between the Danube and the Hadriatic, was one of the last and most difficult conquests of the Romans. In the defence of national freedom, two hundred thousand of these barbarians had once appeared in the field, alarmed the declining age of Augustus, and exercised the vigilant prudence of Tiberius at the head of the collected force of the empire. The Pannonians yielded at length to the arms and institutions of Rome. Their recent subjection, however, the neighborhood, and even the mixture, of the unconquered tribes, and perhaps the climate, adapted, as it has been observed, to the production of great bodies and slow minds, all contributed to preserve some remains of their original ferocity, and under the tame and uniform countenance of Roman provincials, the hardy features of the natives were still to be discerned. Their warlike youth afforded an inexhaustible supply of recruits to the legions stationed on the banks of the Danube, and which, from a perpetual warfare against the Germans and Sarmazans, were deservedly esteemed the best troops in the service.

The Pannonian army was at this time commanded by Septimius Severus, a native of Africa, who, in the gradual ascent of private honors, had concealed his daring ambition, which was never diverted from its steady course by the allurements of pleasure, the apprehension of danger, or the feelings of humanity. On the first news of the murder of Pertinax, he assembled his troops, painted in the most lively colors the crime, the insolence, and the weakness of the Prætorian guards, and animated the legions to arms and to revenge. He concluded (and the peroration was thought extremely eloquent) with promising every soldier about four hundred pounds; an honorable donative, double in value to the infamous bribe with which Julian had purchased the empire. The acclamations of the army immediately saluted Severus with the names of Augustus, Pertinax, and Emperor; and he thus attained the lofty station to which he was invited, by conscious merit and a long train of dreams and omens, the fruitful offsprings either of his superstition or policy.

The new candidate for empire saw and improved the peculiar advantage of his situation. His province extended to the Julian Alps, which gave an easy access into Italy; and he remembered the saying of Augustus, That a Pannonian army might in ten days appear in sight of Rome. By a celerity proportioned to the greatness of the occasion, he might reasonably hope to revenge Pertinax, punish Julian, and receive the homage of the senate and people, as their lawful emperor, before his competitors, separated from Italy by an immense tract of sea and land, were apprised of his success, or even of his election. During the whole expedition, he scarcely allowed himself any moments for sleep or food; marching on foot, and in complete armor, at the head of his columns, he insinuated himself into the confidence and affection of his troops, pressed their diligence, revived their spirits, animated their hopes, and was well satisfied to share the hardships of the meanest soldier, whilst he kept in view the infinite superiority of his reward.