Persians, with their very
numerous force, made no attempt to hinder them from crossing so very
considerable a river; for Xenophon estimates the Zab at 400 feet
broad,--and this seems below the statement of modern travellers, who
inform us that it contains not much less water than the Tigris; and
though usually deeper and narrower, cannot be much narrower at any
fordable place. It is to be recollected that the Persians, habitually
marching in advance of the Greeks, must have reached the river first,
and were therefore in possession of the crossing, whether bridge or
ford. Though on the watch for every opportunity of perfidy, Tissaphernes
did not dare to resist the Greeks, even in the most advantageous
position, and ventured only 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, heavy-armed
foot-soldiers and light-armed foot-soldiers, 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[51] 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.[52] 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.

"Thank Heaven" (said Xenophon in the evening, when Cheirisophus
reproached him for imprudence in quitting the main body to charge
cavalry, whom yet he could not reach), "Thank Heaven, that our enemies
attacked us with a small detachment only, and not with their great
numbers. They have given us a valuable lesson, without doing us any
serious harm." Profiting by the lesson, the Greek leaders organized
during the night and during the halt of the next day, a small body of
fifty cavalry; with 200 Rhodian[53] slingers, whose slings, furnished
with leaden bullets, both carried farther and struck harder than those
of the Persians hurling large stones. On the ensuing morning, they
started before daybreak, si