They selected for the service large and powerful animals, chiefly of the Nisaean breed, and cased them almost wholly in mail.

The head was guarded by a frontlet, and the neck and chest by a breast-piece; the sides and flanks had their own special covering and cuisses defended the thighs.

These defences were not merely, like those of the later Assyrian heavy cavalry, of felt or leather, but consisted, like the cuirasses worn by the riders, of some such material covered with metal scales.

The weight which the horse had to sustain was thus very great, and the movements of the cavalry force were, in consequence, slow and hesitating.

Flight was difficult; and, in a retreat, the weaker animals were apt to sink under their burdens, and to be trampled to death by the stronger ones.
There can be no doubt that, besides these heavy horsemen, the Persians employed, even in the latest times, and much more in the earlier, a light and agile cavalry force.