Tigris, and when that was forced he seems
to have despaired, and to have made no further effort. His towns and
strongholds were taken one after another, without their offering any
serious resistance. Nineveh, Arbela, and Gaugamala fell into the enemy's
hands. Adenystrse, a place of great strength, was captured by a small
knot of Roman prisoners, who, when they found their friends near, rose
upon the garrison, killed the commandant, and opened the gates to their
countrymen. In a short time the whole tract between the Tigris and the
Zagros mountains was overrun; resistance ceased; and the invader was
able to proceed to further conquests.

It might have been expected that an advance would have at once been
directed on Ctesiphon, the Parthian capital; but Trajan, for some reason
which is not made clear to us, determined otherwise. He repassed the
Tigris into Mesopotamia, took Hatra (now el-Hadhr), at that time one of
the most considerable places in those parts, and then, crossing to the
Euphrates, descended its course to Hit and Babylon. No resistance was
offered him, and he became master of the mighty Babylon without a blow.
Seleucia seems also to have submitted; and it remained only to attack
and take the capital in order to have complete possession of the entire
region watered by the two great rivers. For this purpose a fleet was
again necessary, and, as the ships used on the upper Tigris had, it
would seem, been abandoned, Trajan conveyed a flotilla, which had
descended the Euphrates, across Mesopotamia on rollers, and launching it
upon the Tigris, proceeded to the attack of the great metropolis. Here
again the resistance that he encountered was trivial. Like Babylon and
Seleucia, Ctesiphon at once opened its gates. The monarch had departed
with his family and his chief treasures,6 and had placed a vast space
between himself and his antagonist. He was prepared to contend with
his Roman foe, not in battle array, but by means of distance, natural
obstacles, and guerilla warfare. He had evidently determined neither
to risk a battle nor stand a siege. As Trajan advanced, he retreated,
seeming to yield all, but no doubt intending, if it should be necessary,
to turn to bay at last, and in the meantime diligently fomenting that
spirit of discontent and disaffection which was shortly to render the
further advance of the Imperial troops impossible.

But, for the moment, all appeared to go well with the invaders. The
surrender