upon sending Mithridates to harass the rear; which he executed with considerable effect. The bowmen and darters of the Greeks, few in number, were at the same time inferior to those of the Persians; and when Xenophon employed his rear guard, hoplites and peltasts, to charge and repel them, he not only could never overtake any one, but suffered much in getting back to rejoin his own main body. Even when retiring, the Persian horseman could discharge his arrow or cast his javelin behind him with effect; a dexterity which the Parthians exhibited afterwards still more signally, and which the Persian horsemen of the present day parallel with their carbines. This was the first experience which the Greeks had of marching under the harassing attack of cavalry. Even the small detachment of Mithridates greatly delayed their progress; so that they accomplished little more than two miles, reaching the villages in the evening, with many wounded, and much discouragement.[154] [152] Xen. Anab. iii, 3, 6; iii, 5, 43. [153] Xen. Anab. ii, 5, 1. Ainsworth. Travels and Researches in Asia Minor, etc. vol. ii, ch. 44, p. 327; also his Travels in the Track of the Ten Thousand, p. 119-134. Professor Koch, who speaks with personal knowledge both of Armenia and of the region east of the Tigris, observes truly that the Great Zab is the only point (east of the Tigris) which Xenophon assigns in such a manner as to be capable of distinct local identification. He also observes, here as elsewhere, that the number of parasangs specified by Xenophon is essentially delusive as a measure of distance (Zug der Zehn Tausend, p. 64). [154] Xen. Anab. iii, 3, 9.