In the valley of the Hermus, near Magnesia at the foot of Mount Sipylus not far from Smyrna, the Roman troops fell in with the enemy late in the autumn of 564. The force of Antiochus numbered close on 80,000 men, of whom 12,000 were cavalry; the Romans--who had along with them about 5000 Achaeans, Pergamenes, and Macedonian volunteers --had not nearly half that number, but they were so sure of victory, that they did not even wait for the recovery of their general who had remained behind sick at Elaea; Gnaeus Domitius took the command in his stead. Antiochus, in order to be able even to place his immense mass of troops, formed two divisions. In the first were placed the mass of the light troops, the peltasts, bowmen, slingers, the mounted archers of Mysians, Dahae, and Elymaeans, the Arabs on their dromedaries, and the scythe-chariots. In the second division the heavy cavalry (the Cataphractae, a sort of cuirassiers) were stationed on the flanks; next to these, in the intermediate division, the Gallic and Cappadocian infantry; and in the very centre the phalanx armed after the Macedonian fashion, 16,000 strong, the flower of the army, which, however, had not room in the narrow space and had to be drawn up in double files 32 deep. In the space between the two divisions were placed 54 elephants, distributed between the bands of the phalanx and of the heavy cavalry. The Romans stationed but a few squadrons on the left wing, where the river gave protection; the mass of the cavalry and all the light armed were placed on the right, which was led by Eumenes; the legions stood in the centre. Eumenes began the battle by despatching his archers and slingers against the scythe-chariots with orders to shoot at the teams; in a short time not only were these thrown into disorder, but the camel-riders stationed next to them were also carried away, and even in the second division the left wing of heavy cavalry placed behind fell into confusion. Eumenes now threw himself with all the Roman cavalry, numbering 3000 horse, on the mercenary infantry, which was placed in the second division between the phalanx and the left wing of heavy cavalry, and, when these gave way, the cuirassiers who had already fallen into disorder also fled. The phalanx, which had just allowed the light troops to pass through and was preparing to advance against the Roman legions, was hampered by the attack of the cavalry in flank, and compelled to stand still and to form front on both sides--a movement which the depth of its disposition favoured. Had the heavy Asiatic cavalry been at hand, the battle might have been restored; but the left wing was shattered, and the right, led by Antiochus in person, had driven before it the little division of Roman cavalry opposed to it, and had reached the Roman camp, which was with great difficulty defended from its attack. In this way the cavalry were at the decisive moment absent from the scene of action.