253—He was put to death by Emilianus, who attempted to seize the reins of government, but the army elected Valerian, governor of Gaul. The empire was invaded by the Goths on the north and the Persians under their king, Sapor, on the east. From this time, it had to 259—fight for its life. Valerian was defeated by Sapor and remained nine years in captivity, Gallienus, his son, becoming emperor. He was extremely incompetent and a multitude of rival claimants for the supreme authority arose in all directions. They were called the “Thirty Tyrants.” One of them, Odenatus, king of Palmyra, in the Syrian desert, defeated Sapor, and Gallienus proclaimed him his colleague. On the death of Odenatus, his wife, Zenobia, assumed the title of “Queen of the East,” conquered Egypt and ruled a wide region with success and splendor. Both Goths 262—and Persians invaded Asia Minor. Gallienus was murdered 268—and Claudius succeeded. He defeated the Goths 270—but died in a pestilence. Aurelian succeeded. He was an able general. He subdued the Germans and 272—Goths, and conquered Zenobia, one of the most remarkable 275—women of history. Aurelian was assassinated by some victims of his severity, and Tacitus, a Roman senator succeeded, but died in seven months, and was followed by Probus. He was a vigorous general, and drove back the barbarians on all sides, but attempting to employ his soldiers in labor on public works, they 282—revolted and murdered him. Carus, the captain of the 283—imperial guard, was raised to the throne. Dying the next year, his sons, Carinus and Numerianus, inherited his authority, but Numerianus was assassinated in a 284—few months by his father-in-law, and Diocletian, said to have been formerly a slave, was proclaimed emperor by the army. This was called “The Era of the Martyrs,” from the long and bloody persecutions against the Christians. This was the tenth general attack on them, and proved to be the last. The barbarians pressing in great force on all sides, Diocletian appointed several colleagues, and their united ability drove the invaders back. 305—Diocletian resigned his power to Galerius, who appointed three associates, making a division of the empire. One of these, Constantius, died in Britain, and was succeeded 306—by his son, Constantine. For a time, there were six emperors, but one was killed, Galerius died, and Constantine conquered the others.