THE ROMAN EMPIRE 117 one, on lines entirely different from anything that had been anticipated. Marcus Aurelius was succeeded by his son Commodus, one of the worst emperors in the whole series, a painful contrast to his great father. After a few years of debauchery 3 The and tyranny he was murdered ; and there was a Later scramble for the- throne among the leaders of the Em P ire - legions, just as there had been on the fall of Nero. Success fell to Septimius Severus, a soldier who claimed to be of Carthaginian descent. Severus was carried into office by the legions of Pannonia, the frontier province lying between Italy and the Danube, where the troops were now composed to an immense extent of barbarians, in other words tribes mainly Teutonic. This was owing to a step which Marcus Aurelius E n ii 8 t me nt had found himself compelled to take. It had been of necessary hastily to enrol a large number of recruits. BarDanans - Theoretically, the legions could only be recruited from Roman citizens; consequently, the bestowal of citizenship had accom- panied enlistment. Hence, it was habitually the case from this time that the hardiest legions with the most experience in war and the most effective power of deciding succession to the empire were in fact largely made up of barbarians. Severus proved a vigorous emperor, but his energies were chiefly devoted to warfare on the frontiers. Like Hadrian he visited both the east and the west, and died at York. His son and successor Caracalla was notable for his vices and his cruel- ties, and also for having at one stroke bestowed Roman citizenship on all the provincials. One emperor after another succeeded by the favour of the legions. In a.d. 249 their choice was Decius, in whom we find once more a member of a family which had been • , Decius, 249. famous in the days of the Roman republic. His reign was brief, and was notable for a severe persecution of the Christians. Throughout this third century of the Christian era the barbarians were bursting in over the frontiers. The appear- ance begins of the Franks of whom we shall hear The Bar- more later j of the Allemanni, who supplied one of Darians. the general names applied to the German tribes ; and of the Goths,
