Thapsakus appears to have been the most frequented and best-known passage over the Euphrates, throughout the duration of the Seleukid kings, down to 100 B.C. It was selected as a noted point, to which observations and calculations might be conveniently referred, by Eratosthenes and other geographers (see Strabo, ii, p. 79-87). After the time when the Roman empire became extended to the Euphrates, the new Zeugma, higher up the river near Bir or Bihrejik (about the 37th parallel of latitude) became more used and better known, at least to the Roman writers. The passage at Thapsakus was in the line of road from Palmyra to Karrhæ in Northern Mesopotamia; also from Seleukeia (on the Tigris below Bagdad) to the other cities founded in Northern Syria by Seleukus Nikator and his successors, Antioch on the Orontes, Seleukeia in Pieria, Laodikeia, Antioch ad Taurum, etc. The ford at Thapsakus (says Mr. Ainsworth, p. 69, 70) “is celebrated to this day as the ford of the Anezeh or Beduins. On the right bank of the Euphrates there are the remains of a paved causeway leading to the very banks of the river, and continued on the opposite side.” Cyrus remained at Thapsakus five days. He was now compelled formally to make known to his soldiers the real object of the march, hitherto, in name at least, disguised. He accordingly sent for the Greek generals, and desired them to communicate publicly the fact, that he was on the advance to Babylon against his brother,—which to themselves, probably, had been for some time well known. Among the soldiers, however, the first announcement excited loud murmurs, accompanied by accusation against the generals, of having betrayed them, in privity with Cyrus. But this outburst was very different to the strenuous repugnance which they had before manifested at Tarsus. Evidently they suspected, and had almost made up their minds to, the real truth; so that their complaint was soon converted into a demand for a donation to each man, as soon as they should reach Babylon; as much as that which Cyrus had given to his Grecian detachment on going up thither before. Cyrus willingly promised them five minæ per head (about £19 5_s._), equal to more than a year’s pay, at the rate recently stipulated of a daric and a half per month. He engaged to give them, besides, the full rate of pay until they should have been sent back to the Ionian coast. Such ample offers satisfied the Greeks, and served to counterbalance at least, if not to efface, the terrors of that unknown region which they were about to tread.