Three months later, Maximus and Balbinus, on July 15, 238, fell victims to their own virtues at the hands of the Praetorian guard, Gordian became emperor.  At the end of six years, he, too, after an innocent and virtuous reign, succumbed to the ambition of the prefect Philip, while engaged in a war with Persia, and in March 244, the Roman world recognized the sovereignty of an Arabian robber.

Returning to Rome, Philip celebrated the secular games, on the accomplishment of the full period of a thousand years from the foundation of Rome.  From that date, which marked the fifth time that these rites had been performed in the history of the city, for the next twenty years the Roman world was afflicted by barbarous invaders and military tyrants, and the ruined empire seemed to approach the last and fatal moment of its dissolution.  Six emperors in turn succeeded to the sceptre of Philip and ended their lives, either as the victims of military licence, or in the vain attempt to stay the triumphal eruption of the Goths and the Franks and the Suevi.  In three expeditions the Goths seized the Bosphorus, plundered the cities of Bithynia, ravaged Greece, and threatened Italy, while the Franks invaded Gaul, overran Spain and the provinces of Africa.

Some sparks of their ancient virtue enabled the senate to repulse the Suevi, who threatened Rome herself, but the miseries of the empire were not assuaged by this one triumph, and the successes of Sapor, king of Persia, in the East, seemed to foreshadow the immediate downfall of Rome.  Six emperors and thirty tyrants attempted in vain to stay the course of disaster.  Famine and pestilence, tumults and disorders, and a great diminution of the population marked this period, which ended with the death of the Emperor Gallienus on March 20, 268.

V.—­Restorers of the Roman World

The empire, which had been oppressed and almost destroyed by the soldiers, the tyrants, and the barbarians, was saved by a series of great princes, who derived their obscure origin from the martial provinces of Illyricum.  Within a period of about thirty years, Claudius, Aurelian, Probus, Diocletian and his colleagues triumphed over the foreign and domestic enemies of the state, re-established, with a military discipline, the strength of the frontier, and deserved the glorious title of Restorers of the Roman world.

Claudius gained a crushing victory over the Goths, whose discomfiture was completed by disease in the year 269.  And his successor, Aurelian, in a reign of less than five years, put an end to the Gothic war, chastised the Germans who invaded Italy, recovered Gaul, Spain, and Britain from the Roman usurpers, and destroyed the proud monarchy which Zenobia, Queen of Palmyra, had erected in the East on the ruins of the afflicted empire.

The murder of Aurelian in the East (January 275) led to a curious revival of the authority of the senate.  During an interregnum of eight months the ancient assembly at Rome governed with the consent of the army, and appeared to regain with the election of Tacitus, one of their members, all their ancient prerogatives.  Their authority expired, however, with the death of his successor, Probus, who delivered the empire once more from the invasions of the barbarians, and succumbed to the too common fate of assassination in August 282.