us 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 had 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 Macriarius
and his son, Quietus, turned his arms once more, about A.D. 263, against
the Persians, crossed the Euphrates into Mesopotamia, took Oarrhee 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
ventured to form the siege of 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).

The successes of Odenathus in A.D. 263 were followed by a period of
comparative tranquillity. That ambitious prince seems to have been
content with ruling from the Tigris to the Mediterranean, and with
the titles of "Augustus," which he received from the Roman emperor,
Gallienus, and "king of kings," which he assumed upon his coins. He did
not press further upon Sapor; nor did the Roman emperor make any serious
attempt to recover his father's person or revenge his defeat upon the
Persians. An expedition which he sent out to the East, professedly
with this object, in the year A.D. 267, failed utterly, its commander,
He