The hostile feeling of Odenathus against Sapor did not cease with the retreat of the latter across the Euphrates. The Palmyrene prince was bent on taking advantage of the general confusion of the times to carve out for himself a considerable kingdom, of which Palmyra should be the capital. Syria and Palestine, on the one hand, Mesopotamia, on the other, were the provinces that lay most conveniently near to him and that he especially coveted. But Mesopotamia had remained in the possession of the Persians as the prize of their victory over Valerian, and could only be obtained by wresting it from the hands into which it had fallen. Odenathus did not shrink from this contest. It has been, with some reason, conjectured that Sapor must have been at this time occupied with troubles which had broken out on the eastern side of his empire. At any rate, it appears that Odenathus, after a short contest with Macrianus and his son, Quietus, turned his arms once more, about A.D. 263, against the Persians, crossed the Euphrates into Mesopotamia, took Carrhæ and Nisibis, defeated Sapor and some of his sons in a battle, and drove the entire Persian host in confusion to the gates of Ctesiphon. He even returned to lay siege to that city; but it was not long before effectual relief arrived; from all the provinces flocked in contingents for the defence of the western capital; several engagements were fought, in some of which Odenathus was defeated; and at last he found himself involved in difficulties through his ignorance of the localities, and so thought it best to retire. Apparently his retreat was undisturbed; he succeeded in carrying off his booty and his prisoners, among whom were several satraps, and he retained possession of Mesopotamia, which continued to form a part of the Palmyrene kingdom until the capture of Zenobia by Aurelian, A.D. 273.