The succession to the imperial throne continued to be the weak point of the whole system. The throne itself passed through unspeakable degradations. The guards who murdered Pertinax formally put the succession up to auction in the prætorian camp. Septimius Severus (193-198) gave a brief respite of strong government which almost destroyed the fiction of senatorial authority, for Severus held the proconsular power even over Rome and Italy. Caracalla was probably the worst of all the emperors in personal vice and brutality, but he was the author of that famous decree which conferred the citizenship on all the western provinces. In Elagabalus (218-222) Rome had for master the vile and effeminate priest of the Sungod, who brought the fetish-stone of Emesa into the city and attempted to make all the gods bow down to it. Alexander Severus was a blameless prince, and Maximin the Thracian drove the barbarians back behind the _limites_ of the Rhine and Danube. After the Gordians the senate enjoyed for a brief space the opportunity of governing Rome through their nominee Pupienus, but the disorders of the period may be gauged from the fact that in the eighteen years following Alexander Severus, who died in 235, twelve persons wore the purple. Then Gallienus assumed it, having for his colleague that Valerian who was the first of Roman emperors to be taken prisoner by the enemy. Strange and horrible tales hung about his mysterious fate when taken captive by Shapur, the Persian king. In the latter years of Gallienus the Empire was practically divided, for his rebellious general Postumus was recognised as emperor throughout Gaul, Spain, and Britain. In this period, too, Palmyra rose into independent power as the meeting-place of the caravan routes across the Syrian plains. Under the famous Queen Zenobia it practically ruled over the eastern parts of the Empire, and its splendid ruins prove its wealth and magnificence. Gallienus then almost allowed the Empire to disintegrate under his feeble grasp, but his successor Claudius Gothicus (268) was a man and a soldier. He smote the Goths and would have restored the Empire in full, but the plague, which had never wholly disappeared since the time of Marcus Aurelius, carried him off in the third year of his reign. The task was left for Aurelian, that Pannonian peasant whose brilliant generalship hurled back the enemy on every side, while his statesmanship restored the authority of the emperor and even the financial credit of the Empire. The mighty wall with which he surrounded Rome is, however, a sad testimony of the dark days upon which the imperial city had fallen. The Palmyrene kingdom was defeated and the rich city plundered. The rebel Empire of the Gauls was destroyed for ever. The grandest triumph ever witnessed in Rome was that of Aurelian in 274. It is thus described by Vopiscus: