Anabasis VII

In spite of their concerns caused by the lengthy delay, the Greeks abide by the truce and wait to be led out by the Persian forces. This march begins in conditions of mutual suspicion, at least between the Greeks and the Persians. The Persian allies of Cyrus begin to camp with their relatives, mending fences as is the normal way after the war. That only makes the Greeks feel more isolated. 

Nevertheless there have been arrangements made for food, and after a while the Greeks come to the Median Wall. 

This wall was built of burnt bricks, laid in bitumen ; it was twenty feet in thickness, and a hundred in height, and the length of it was said to be twenty parasangs; and it was not far distant from Babylon.

"Not the least remarkable of the discoveries," says the Rev. J. F. Macmichael in the Appendix to his Xenophon, "which of late years have marked the progress of geographical inquiry in this most interesting - but, till of late, unexplored region, is the actual existence at the present time of an ancient wall stretching across Mesopotamia at the head of the Babylonian plain. Mr. Ross, who first examined it at its eastern terminus, in 1836, described it under the name of Khalu or Sidd Nimrud, (wall or embankment of Nimrod,) and as a straight wall 25 long paces thick, and from 35 to 40 feet high, running S. W. :} N. as far as the eye could reach, to two mounds called Ramelah, (Sifairah, Ainswr. p. 81-2,) on the Euphrates, some hours above Felujah. The eastern extremity was built of the small pebbles of the country, cemented with lime of great tenacity; and farther inland, his Bedwin guides told him it was built of brick, and in some places worn down level with the desert, and was built by Nimrod to keep off the people of Nineveh, with whom he had an implacable feud. (Journal of R. Geog. S. ix. p. 446.)

So we are north of Fallujah, which is in Anbar province, but somewhere east of it. Xenophon says that the armies "passed over to the other side of it," which is not very adequate detail for a wall a hundred feet wide and maybe seventy miles long. (Remember that a 'parasang' is not strictly a measure of distance, but a rough measure of time spent traveling.) It would be interesting to know more about how one passed this wall, whether by wooden ramps that could be pulled up, or dirt ramps that had to be destroyed if enemies were approaching, or in some other way. By tradition, there were towers constructed and manned at intervals during the era that the wall was a defensive structure.

An 1877 illustration imagines the wall.

We end up learning very little from Xenophon about this wonder of the world, which I might have thought would make a larger impression upon him. I suppose he was focused on the problem of getting out more than the enjoyment of the sights.

There are reports of plotted attacks by native forces, which the Greeks analyze sensibly and don't get too excited about, although they take due precautions. None materialize during this period.

For some reason, however, they are marching east and not north or west. They come to the Tigris, and eventually to the ancient city of Opis. This is very near to modern Baghdad, but east of it. The reason is hinted at when we learn that the country they are marching through belonged to Cyrus' family, including his mother and his bastard brother. They meet the brother in passing, going with an army to report to the King for service -- doubtless to prove his loyalty after his brother's betrayal. The Persian commander, Tissaphernes, allows them to plunder two villages belonging to Cyrus' mother as a way of insulting his family and provisioning the Greeks. 

They now turn north along the Tigris and march another sixty miles, passing a city called Caenae and then coming to a river called Zapatas. It is not clear to me precisely where these would be from my knowledge of the area.