XXIII. It is said that on that day Crassus did not appear, as is the custom of Roman generals, in a purple dress, but in black, which he immediately changed on observing what he had done: and it is also said that the men who carried the standards had much difficulty in raising some of them up, for they stuck in the ground as if they were firmly rooted there. Crassus ridiculed all these omens, and quickened his march, urging the infantry to follow after the cavalry, till at last a few of those who had been sent forward as scouts came up, and reported that the rest of them had been cut off by the enemy, and they had escaped with difficulty, and that the Parthians were advancing with a large force, and full of confidence. This threw all the army into confusion, and Crassus was completely confounded, and began to put his men in order hastily, and with no great presence of mind: at first, as Cassius recommended, he extended the line of the legionary soldiers as far as possible in the plain, and making it of small depth, in order to prevent the enemy from attacking them on the flank, he distributed the cavalry on the wings; but he changed his plan and, drawing his men together, formed them into a deep square of four fronts, with twelve cohorts on each side. By the side of each cohort he placed a body of horse, in order that no part of the army might be without the aid of the cavalry, but might make the attack equally protected on all sides. He gave one of the wings to Cassius, and the other to young Crassus; he himself took his station in the centre. Thus advancing, they came to a stream called Balissus,[70] which was neither large nor copious; but it was a joyful sight to the soldiers in the midst of the drought and heat, and by comparison with the rest of their laborious march through a country without water. Now most of the commanders thought that they ought to encamp and spend the night there, and learn what was the number of the enemy, and the nature and disposition of their force, and so advance against them at daybreak; but Crassus, being prevailed upon by the importunity of his son, and the cavalry with him, to advance immediately, and engage with the enemy, gave orders for the men who required it to eat and drink in their ranks. And before this could be well accomplished all through the ranks, he led on his men, not slowly, nor halting at intervals, as is usual when men are marching to battle, but he kept them up to a quick, unbroken pace, until the enemy were in sight, who, contrary to expectation, did not appear to the Romans to be either numerous or formidable; for Surena disguised his numbers by placing the mass of his force behind the front ranks, and he prevented their bright armour from being seen by ordering his men to cover themselves with cloaks and skins. But when they were near the Romans, and the standard was raised by the general, first of all they filled the plain with a deep sound and a terrific noise; for the Parthians do not excite themselves to battle with horns or trumpets, but they have hollow instruments,[71] made of skin, and furnished with brass bells, on which they strike at the same time in various parts; and these instruments produce a kind of deep and dismal sound, compounded of the roaring of wild beasts and the harsh crash of thunder; for the Parthians rightly judge that of all the senses the hearing is that which causes the greatest alarm in the mind, and that, when this sense is affected, there is the speediest and greatest disturbance in the judgment.