Affairs had now reached a point when it was necessary to form a definite resolution as to what should be the further aim and course of the expedition.  Hitherto all had indicated an intention on the part of Julian to occupy Ctesiphon, and thence dictate a peace.  His long march, his toilsome canal-cutting, his orders to his second army, his crossing of the Tigris, his engagement with the Persians in the plain before Ctesiphon, were the natural steps conducting to such a result, and are explicable on one hypothesis and one hypothesis only.  He must up to this time have designed to make himself master of the great city, which had been the goal of so many previous invasions, and had always fallen whenever Rome attacked it.  But, having overcome all the obstacles in his path, and having it in his power at once to commence the siege, a sudden doubt appears to have assailed him as to the practicability of the undertaking.  It can scarcely be supposed that the city was really stronger now than it had been under the Parthians; much less can it be argued that Julian’s army was insufficient for the investment of such a place.  It was probably the most powerful army with which the Romans had as yet invaded Southern Mesopotamia; and it was amply provided with all the appurtenances of war.  If Julian did not venture to attempt what Trajan and Avidius Cassius and Septimius Severus had achieved without difficulty, it must have been because the circumstances under which he would have had to make the attack were different from those under which they had ventured and succeeded.  And the difference—­a most momentous one—­was this.  They besieged and captured the place after defeating the greatest force that Parthia could bring into the field against them.  Julian found himself in front of Ctesiphon before he had crossed swords with the Persian king, or so much as set eyes on the grand army which Sapor was known to have collected.  To have sat down before Ctesiphon under such circumstances would have been to expose himself to great peril; while he was intent upon the siege, he might at any time have been attacked by a relieving army under the Great King, have been placed between two fires, and compelled to engage at extreme disadvantage.  It was a consideration of this danger that impelled the council of war, whereto he submitted the question, to pronounce the siege of Ctesiphon too hazardous an operation, and to dissuade the emperor from attempting it.

But, if the city were not to be besieged, what course could with any prudence be adopted?  It would have been madness to leave Ctesiphon unassailed, and to press forward against Susa and Persepolis.  It would have been futile to remain encamped before the walls without commencing a siege.  The heats of summer had arrived, and the malaria of autumn was not far off.  The stores brought by the fleet were exhausted; and there was a great risk in the army’s depending wholly for its subsistence on the supplies