The Roman senate recognised the deeds of Odenathus by granting him the title of Augustus, A.D. 263. In the following year the royal pair undertook a second expedition against Sapor. New triumphs were added to the glories of the last campaign. The Persian king was once more forced to take refuge in Ctesiphon, which would no doubt have fallen had not the incursion of a horde of Scythian Goths into Syria compelled Odenathus to raise the siege. Surrounding nations soon learned to respect the brave prince of Palmyra and his no less warlike consort. Even Sapor, humiliated though he had been, was glad, not merely to make peace, but to join in close alliance with his conquerors, who were threatened by the underhand machinations of the contemptible emperor Gallienus. But the brilliant career of Odenathus was unexpectedly brought to a close by the hand of his nephew, who, believing himself insulted by the monarch, assassinated him, together with his son Herod, at a banquet in the city of Emesa, A.D. 267. The murderer gained nothing but the empty pleasure of revenge. Scarcely had he assumed the title of Augustus ere he was sacrificed by the royal widow to the memory of her husband, though some historians have accused her of being an accomplice in the double murder. Zenobia was proclaimed queen; and, passing over Timolaus and Herennius, her sons by Odenathus, she arrayed Vhaballathus in the purple, and showed him to the troops as their emperor. With the death of Odenathus ceased that authority granted him as a personal favour by the emperor and senate of Rome; and Gallienus despatched an army to dethrone Zenobia. But the queen soon compelled the Roman general to retreat into Europe with the loss of both army and reputation. Zenobia governed the East for more than five years; and by successive conquests she extended her dominions from the Euphrates to the Mediterranean and the borders of Bithynia; and added, besides, the land of the Ptolemies. Her power became so great that the warlike Claudius II., who succeeded Gallienus, was satisfied that while he was occupied in the defence of Italy from the Goths and Germans, Zenobia should assert the dignity of the Roman power in the East. Palmyra, the capital of the warrior queen, almost rivalled the Eternal City in the magnificence of its temples, its mansions, its public monuments, and the luxury of its citizens. It became the great centre of commerce between Europe and India, and its merchants grew wealthy through the trade of East and West. Arcades of lofty palms shadowed its streets of marble palaces; purling fountains, fed by icy springs, rendered it a perfect Elysium in the midst of burning arid sands. Schools, museums, libraries, fostered by the care of Zenobia, encouraged and aided the arts and literature.