At last the stern, the inflexible Aurelian ascended the throne of the Cæsars. Firmly resolved to rid the empire of every usurper, great or small, he began by re-conquering Gaul and making prisoner the Western usurper, Tetricus. He then passed into Asia, A.D. 272, when his presence alone was sufficient to bring back Bithynia to its allegiance. Of course Zenobia did not indolently permit an invader to approach within a hundred miles of her capital without taking measures to arrest his progress. She marched with all her forces to oppose him; but was signally defeated in two battles, the first near Antioch, the second near Emesa. In both engagements the queen animated the soldiers by her presence, though the actual command devolved on Zabdas, the conqueror of Egypt. The latter, Zenobia's principal general, has been by many supposed to have been Zabba, the queen's sister; this, however, is mere surmise. After the second defeat, Zenobia was unable to raise a third army. She retired within the walls of her capital, prepared to make a gallant defence, and boldly declared that her reign and her life should end together. Aurelian arrived before Palmyra, after a toilsome march over the sandy desert which separated the city from Antioch. His proposals being rejected with scorn, he was obliged to begin the siege; and, while superintending the operations, he was wounded by a dart. "The Roman people," he wrote in a letter, "speak with contempt of the war which I am waging against a woman. They are ignorant both of the character and of the power of Zenobia. It is impossible to enumerate her warlike preparations of stones, of arrows, and of every species of missile weapons. Every part of the walls is provided with two or three balistæ, and artificial fires are thrown from her military engines. The fear of punishment has armed her with a desperate courage." Zenobia was at first supported in her determined resistance by the hope that the Roman army, having no means of getting provisions, would soon be compelled to retreat, and also by the expectation that Persia would come to her aid. Disappointed in both calculations, she mounted her swiftest dromedary and fled towards the Euphrates. But the Roman light cavalry pursued, and soon overtook the queen, who was brought back prisoner. Palmyra surrendered almost immediately after, and was treated with unexpected clemency by the victor. The courage of Zenobia entirely deserted her when she heard the angry cries of the soldiers, who clamoured for her immediate execution. She threw the entire guilt of her obstinate resistance upon her friends and counsellors, and the celebrated Longinus, amongst others, fell a victim to the emperor's rage. Vhaballathus, the only surviving son of Zenobia, withdrew into Armenia, where he ruled over a small principality granted him by Aurelian.