A son of Decius, Hostilianus, together with Gallus, an experienced soldier, were now made emperors. They concluded a disgraceful, but probably necessary peace with the Goths. But Hostilianus soon after died, and Gallus was defeated and slain by Æmilianus, who was himself assassinated, and Valerian, the Censor, in A.D. 253, was made emperor. A very high character is given of this ruler, whose reign, however, was filled with disasters. Having joined his son Gallienus with him, Valerian vainly sought to repel the attacks of innumerable enemies on every side of the empire—the Goths, the Franks, the Scythians, and the Persians. In a campaign against the latter Valerian was taken prisoner, and for nine years languished in captivity, his unnatural son making no effort for his liberation.
The Allemanni, meanwhile, had entered Italy, ravaged its northern territory, and even threatened Rome. They withdrew, loaded with plunder. To gain allies among the barbarians, Gallienus now married the daughter of the king of the Marcomanni. Every part of the empire seems now to have been laid open to the invaders. Greece was ravaged by the Goths; the famous Temple of Diana at Ephesus was burned by them, together with that fine city; and Sapor, king of the Persians, overran Syria and Asia. He was, however, finally repelled by the brave Odenatus, who, with his queen Zenobia, ruled at Palmyra.
Valerian died in captivity, while a crowd of usurpers rose in arms against the weak Gallienus. There were nineteen pretenders to the throne according to Gibbon, but this period is usually known as that of the Thirty Tyrants. This melancholy period was also marked by a pestilence, which raged for fifteen years in every province. Five thousand persons are said to have died daily at Rome for some time; cities were depopulated, and the number of the human species must have sensibly declined. A famine preceded and attended the pestilence, earthquakes were common, and the third century is, no doubt, the most melancholy period in the history of Europe.
Gallienus was murdered in A.D. 268, and was succeeded by Marcus Aurelius Claudius, who died of a pestilence which had broken out in his army in Egypt. Aurelian, a native of Pannonia, was the next emperor. His reign lasted four years and nine months, but was filled with remarkable events. He abandoned Dacia to the Goths, defeated the Alemanni, and drove them out of Italy. But he foresaw the danger of future invasions, and surrounded Rome with new walls about twenty-one miles in extent. In A.D. 272 he marched against Zenobia, queen of Palmyra, who ventured to defy the power of Rome. This illustrious woman was not only learned, beautiful, and an agreeable writer, but governed the East for five years with discretion and success. Aurelian was amazed at her warlike preparations upon the fall of Palmyra, and treated her beautiful city with lenity; but the Palmyrenians having rebelled, the city was taken by storm, and its people put to death. The ruins of Palmyra are still among the most remarkable of the ancient world.
Aurelian now returned to Rome to celebrate his triumph. The spoils of every climate were borne before him; his captives were from Germany, Syria, and Egypt, and among them were the Emperor Tetricus and the beautiful Zenobia, bound with fetters of gold. A whole day was consumed in the passage of the triumphal procession through the streets of Rome. But Aurelian, who was illiterate, unpolished, and severe, failed to win the regard of his people, and was plainly more at his ease at the head of his army than in the cultivated society of Rome. He returned, therefore, to the East, where he died, as was usual with so many of the emperors, by the hand of an assassin, in A.D. 275. He restored vigor to the empire, and preserved it from instant destruction.
The army, filled with sorrow for the loss of the emperor, revenged his death by tearing his assassin in pieces; and they then wrote a respectful letter to the Senate, asking the Senators to select his successor. The Senate, however, passed a decree that the army should name the new emperor. The soldiers, in their turn, refused, and thus for eight months an interregnum prevailed while this friendly contest continued. At last the Senate appointed the virtuous Tacitus, who claimed a descent from his namesake, the famous historian. Tacitus, however, who was seventy years old, sank under the hardships of his first campaign, and died A.D. 276, at Tyania, in Cappadocia.
His brother Florian then ascended the throne, but was defeated and put to death by Probus, the best soldier of the age, who, in six years, once more repelled the barbarians from every part of the empire. He delivered Gaul from the ravages of the Germans, pursued them across the Rhine, and every where defeated them. He suppressed, also, several insurrections, and employed his soldiers in various useful works. But at length, weary of these labors, they put Probus to death, A.D. 282.
Carus, the next emperor, was singularly frugal in his mode of life. When the Persian embassadors visited him in his tent they found him sitting upon the grass, clothed in a coarse robe, and eating his supper of bacon and hard pease. Carus gained many victories over the Persians, but died suddenly in A.D. 283. His two sons, Carinus and Namerian, succeeded him, but were soon assassinated, giving place to the more famous Diocletian.