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 of Ctesiphon brought with it the submission of the whole region on the lower courses of the great rivers, and gave the conqueror access to the waters of a new sea.  Trajan may be excused if he overrated his successes, regarded himself as another Alexander, and deemed that the great monarchy, so long the rival of Rome, was now at last swept away, and that the entire East was on the point of being absorbed into the Roman Empire.  The capture by his lieutenants of the golden throne of the Parthian kings may well have seemed to him emblematic of this change; and the flight of Chosroes into the remote and barbarous regions of the far East may have helped to lull his adversary into a feeling of complete security.  Such a feeling is implied in the pleasure voyage of the conqueror down the Tigris to the Persian Gulf, in his embarkation on the waters of the Southern Sea, in the inquiries which he instituted with respect to Indian affairs, and in the regret to which he gave utterance, that his advanced years prevented him from making India the term of his labors.  No shadow of his coming troubles seems to have flitted before the eyes of the Emperor during the weeks that he was thus occupied—­weeks which he passed in self-complacent contemplation of the past and dreams of an impossible future.