his troops,
having attempted nothing, and quietly returned to his capital! It is by
no means difficult to understand the motives which actuated Constantius.
He was, month after month, receiving intelligence from the West of steps
taken by Julian which amounted to open rebellion, and challenged him
to engage in civil war. So long as Sapor threatened invasion he did not
like to quit Mesopotamia, lest he might appear to have sacrificed the
interests of his country to his own private quarrels; but he must have
been anxious to return to the seat of empire from the first moment that
intelligence reached him of Julian's assumption of the imperial name and
dignity; and when Sapor's retreat was announced he naturally made all
haste to reach his capital. Meanwhile the desire of keeping his army
intact caused him to refrain from any movement which involved the
slightest risk of bringing on a battle, and, in fact, reduced him
to inaction. So much is readily intelligible. But what at this time
withheld Sapor, when he had so grand an opportunity of making an
impression upon Rome--what paralyzed his arm when it might have struck
with such effect it is far from easy to understand, though perhaps
not impossible to conjecture. The historian of the war ascribes his
abstinence to a religious motive, telling us that the auguries were not
favorable for the Persians crossing the Tigris. But there is no other
evidence that the Persians of this period were the slaves of any such
superstition as that noted by Ammianus, nor any probability that a
monarch of Sapor's force of character would have suffered his military
policy to be affected by omens. We must therefore ascribe the conduct
of the Persian king to some cause not recorded by the historian--same
failure of health, or some peril from internal or external enemies which
called him away from the scene of his recent exploits, just at the time
when his continued presence there was most important. Once before in
his lifetime, an invasion of his eastern provinces had required his
immediate presence, and allowed his adversary to quit Mesopotamia and
march against Magnentius. It is not improbable that a fresh attack of
the same or some other barbarians now again happened opportunely for the
Romans, calling Sapor away, and thus enabling Constantius to turn his
hack upon the East, and set out for Europe in order to meet Julian.

The meeting, however, was not destined to take place. On his way from
An