f the Tigris. But
the gains made were slight; and in the ensuing year (A.D. 338) Sapor
took the field in greater force than before, and addressed himself to
an important enterprise. He aimed, it is evident, from the first, at
the recovery of Mesopotamia, and at thrusting back the Romans from the
Tigris to the Euphrates. He found it easy to overrun the open country,
to ravage the crops, drive off the cattle, and burn the villages and
homesteads. But the region could not be regarded as conquered, it could
not be permanently held, unless the strongly fortified posts which
commanded it, and which were in the hands of Rome, could be captured.
Of all these the most important was Nisibis. This ancient town, known to
the Assyrians as Nazibina, was, at any rate from the time of Lucullus,
the most important city of Mesopotamia. It was situated at the distance
of about sixty miles from the Tigris, at the edge of the Mons Masius, in
a broad and fertile plain, watered by one of the affluents of the river
Khabour, or Aborrhas. The Romans, after their occupation of Mesopotamia,
had raised it to the rank of a colony; and its defences, which were of
great strength, had always been maintained by the emperors in a state
of efficiency. Sapor regarded it as the key of the Roman position in
the tract between the rivers, and, as early as A.D. 338, sought to make
himself master of it.

The first siege of Nisibis by Sapor lasted, we are told, sixty-three
days. Few particulars of it have come down to us. Sapor had attacked the
city, apparently, in the absence of Constantius, who had been called off
to Pannonia to hold a conference with his brothers. It was defended,
not only by its garrison and inhabitants, but by the prayers and
exhortations of its bishop, St. James, who, if he did not work miracles
for the deliverance of his countrymen, at any rate sustained and
animated their resistance. The result was that the bands of Sapor were
repelled with loss, and he was forced, after wasting two months before
the walls, to raise the siege and own himself baffled.

After this, for some years the Persian war with Rome languished. It is
difficult to extract from the brief statements of epitomizers, and the
loose invectives or panegyrics of orators, the real circumstances of the
struggle; but apparently the general condition of things was this. The
Persians were constantly victorious in the open field; Constantius was
again and again defeated; but no per