Appian, The Syrian Wars 7
Appian of Alexandria (c.95-c.165): one of the most underestimated of all Greek historians, author of a Roman History in twenty-four books.
Although only his books on the Roman Civil Wars survive in their entirety, large parts of Appian's book on the Syrian War, or Syriaca, have also come down to us. This book deals with the war that the Romans and the Seleucid king Antiochus III the Great fought in 192-188, but also discusses, as an appendix, the history of the Seleucid Empire. The Syriaca is a valuable source for the history of the ancient Near East between the reign of Alexander the Great and the Roman conquest.
The translation was made by Horace White; notes by Jona Lendering.
The battle of Magnesia (cont'd)
 Both marched out about the last watch, just before daylight. The ordering of the troops on either side was as follows. The Roman legionaries, to the number of 10,000, formed the left wing resting on the river. Behind these were 10,000 Italian allies, and both these divisions were in files in triple line of battle. Behind the Italians came the army of Eumenes and about 3000 Achaean peltasts. Thus stood the left, while on the right wing were the Roman and Italian cavalry and those of Eumenes, not more than 3000 in all. Mingled with all these were light-armed troops and bowmen, and around Domitius himself were four troops of horse. Altogether they were about 30,000 strong. Domitius took his station on the right wing and placed the consul in the center. He gave the command of the left wing to Eumenes. Considering his African elephants of no use, being few in number and of small size, as those of Africa usually are (and the small ones are afraid of the larger), he placed them in the rear of all. Such was the Roman line of battle.
 The total force of Antiochus was 70,000 and the strongest of these was the Macedonian phalanx of 16,000 men, still arrayed after the fashion of Alexander and Philip. These were placed in the center, divided into ten sections of 1600 men each, with fifty men in the front line of each section and thirty-two deep. On the flanks of each section were twenty-two elephants.note[The Roman historian Livy says that there were two elephants added to each of Antiochus' ten divisions. This is more plausible.] The appearance of the phalanx was like that of a wall, of which the elephants were the towers. Such was the arrangement of the infantry of Antiochus.
His horse were stationed on either wing, consisting of the mail-clad Galatians and the Macedonian corps called the agema, so named because they were picked horsemen. An equal number of these were stationed on either side of the phalanx. Besides these the right wing had certain light-armed troops, and other horsemen with silver shields, and 200 mounted archers. On the left were the Galatian bands of the Tectosagi, the Trocmi, the Tolistoboii, and certain Cappadocians furnished by king Ariarathes, and a mingling of other tribes. There was another body of horse, mail-clad but light-armed, called the Companion cavalry. In this way Antiochus drew up his forces.
He seems to have placed most reliance on his cavalry, whom he stationed in large numbers on his front. The serried phalanx, in which he should have placed most confidence, on account of its high state of discipline, was crowded together unskillfully in a narrow space. Besides the forces enumerated there was a great multitude of slingers, archers, javelin throwers, and peltasts from Phrygia, Lycia, Pamphylia, Pisidia, Crete, Tralles, and Cilicia, armed after the Cretan fashion. There were also other mounted archers from the Dahae, Mysia, Elymais, and Arabia, riding on swift dromedaries, who shot arrows with dexterity from their high position, and used very long thin knives when they came to close combat. Antiochus also placed scythe-bearing chariots in the space between the armies to begin the battle, with orders to retire after the first onset.
 The appearance of his formation was like that of two armies, one to begin the fight, the other held in reserve. Each was arranged in a way to strike terror into the enemy both by numbers and equipment. Antiochus commanded the horse on the right wing in person; his son Seleucus commanded the left. Philip, the master of the elephants, commanded the phalanx, and Mendis and Zeuxis the skirmishers.
The day was dark and gloomy so that the sight of the display was obscured and the aim of the missiles of all kinds impaired by the misty and murky atmosphere. When Eumenes perceived this he disregarded the remainder of the enemy's force, and fearing only the onset of the scythe-bearing chariots, which were mostly ranged against him, he ordered the slingers, archers, and other light-armed under his command to circle around the chariots and aim at the horses, instead of the drivers, for when a horse becomes unmanageable in a chariot all the chariot becomes useless. He often breaks the ranks of his own friends, who are afraid of the scythes.
So it turned out. The horses being wounded in great numbers charged with their chariots upon their own ranks. The dromedaries were thrown into disorder first, as they were next in line to the chariots, and after them the mail-clad horse who could not easily dodge the scythes on account of the weight of their armor. Great was the tumult and various the disorder started chiefly by these runaways and spreading along the whole front, the apprehension being even worse than the fact. For, as by reason of distance and multitude, discordant cries and manifold fears, the truth was not clearly grasped even by those near the danger, so these transmitted the alarm constantly magnified to those beyond.
 Eumenes, having succeeded admirably in his first attempt and cleared the ground held by the dromedaries and chariots, led his own horse and those of the Romans and Italians in his division against the Galatians, the Cappadocians, and the other collection of mercenaries opposed to him, cheering loudly and exhorting them to have no fear of these inexperienced men who had been deprived of their advance supports. They obeyed him and made so heavy a charge that they put to flight not only those, but the adjoining squadrons and the mail-clad horse, who were already thrown into disorder by the chariots. The greater part of these, unable to turn and fly quickly, on account of the weight of their armor, were captured or killed. While this was the state of affairs on the left of the Macedonian phalanx, Antiochus, on the right, broke through the Roman line of battle, dismembered it, and pursued a long distance.
 The Macedonian phalanx, which had been stationed between the two bodies of horse in a narrow space in the form of a square, when denuded of cavalry on either side, had opened to receive the light-armed troops, who had been skirmishing in front, and closed again. Thus crowded together, Domitius easily enclosed them with his numerous light cavalry. Having no opportunity to charge or even to deploy their dense mass, they began to suffer severely; and they were indignant that military experience availed them nothing, exposed as they were on all sides to the weapons of the enemy. Nevertheless, they presented their thick-set pikes on all four sides.
They challenged the Romans to close combat and preserved at all times the appearance of being about to charge. Yet they did not advance, because they were foot-soldiers and heavily armed, and saw that the enemy were mounted. Most of all they feared to relax their close formation lest they might not readily bring it together again.
The Romans did not come to close quarters nor approach them because they feared the discipline, the solidity, and the desperation of this veteran corps; but circled around them and assailed them with javelins and arrows, none of which missed their mark in the dense mass, who could neither turn the missiles aside nor dodge them.
After suffering severely in this way they yielded to necessity and fell back step by step, but with a bold front, in perfect order and still formidable to the Romans. The latter kept their distance and continued to circle around and wound them, until the elephants inside the Macedonian phalanx became excited and unmanageable. Then the phalanx broke into disorderly flight.