How to retrace their steps was now the problem, apparently insoluble. As to the military force of Persia in the field, indeed, not merely the easy victory at Kunaxa, but still more the undisputed march throughout so long a space, left them no serious apprehension. In spite of this great extent, population, and riches, they had been allowed to pass through the most difficult and defensible country, and to ford the broad Euphratês, without a blow: nay, the King had shrunk from defending the long trench which he had specially caused to be dug for the protection of Babylonia. But the difficulties which stood between them and their homes were of a very different character. How were they to find their way back, or obtain provisions, in defiance of a numerous hostile cavalry, which, not without efficiency even in a pitched battle, would be most formidable in opposing their retreat? The line of their upward march had all been planned, with supplies furnished, by Cyrus:--yet even under such advantages, supplies had been on the point of failing, in one part of the march. They were now, for the first time, called upon to think and provide for themselves; without knowledge of either roads or distances--without trustworthy guides--without any one to furnish or even to indicate supplies--and with a territory all hostile, traversed by rivers which they had no means of crossing. Klearchus himself knew nothing of the country, nor of any other river except the Euphratês; nor does he indeed in his heart seem to have conceived retreat as practicable without the consent of the King. The reader who casts his eye on a map of Asia, and imagines the situation of this Greek division on the left bank of the Euphratês, near the parallel of latitude 33° 30'--will hardly be surprised at any measure of despair, on the part either of general or soldiers. And we may add that Klearchus had not even the advantage of such a map, or probably of any map at all, to enable him to shape his course. In this dilemma, the first and most natural impulse was to consult Ariæus; who (as has been already stated) pronounced, with good reason, that return by the same road was impracticable; and promised to conduct them home by another road--longer indeed, yet better supplied. § 2. Commencement of the Retreat.