Polybius, Histories

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The Battle of Issus

Now it is difficult to understand how he could have drawn up these troops in front of his phalanx, considering that the river ran immediately under the camp:¹ especially as their numbers were so great, amounting, on Callisthenes's own showing, to thirty thousand cavalry and thirty thousand mercenaries. Now it is easy to calculate how much ground such a force would require. At the most cavalry in a regular engagement is drawn up eight deep, and between each squadron a clear space must be left in the line to enable them to turn or face about. Therefore eight hundred will cover a stade of front; eight thousand, ten stades;² three thousand two hundred, four stades; and so eleven thousand two hundred would cover the whole of fourteen stades. If therefore he were to put his whole thirty thousand on the ground, he would have to mass his cavalry alone nearly three times the usual depth; and then what room is left for his large force of mercenaries? None, indeed, unless on the rear of the cavalry. But Callisthenes says this was not the case, but that these latter engaged the Macedonians first. We must therefore understand half the front, that nearest the sea, to have been occupied by the cavalry; the other half, that nearest the mountains, by the mercenaries. We may by these data easily calculate the depth of the cavalry, and the distance the river must have been from the camp to allow of it.

Again, he says that "on the approach of the enemy Darius himself, who was on the centre, ordered up the mercenaries from the wing." It is difficult to see what he means by this: for the point of junction of the mercenaries and the cavalry must have been at the centre. Where and how then, and to what point could Darius, who was himself actually among the mercenaries, be said to "order them up"?

Lastly, he says that "the cavalry on the right wing charged Alexander; and that his men stood the charge gallantly, and, making a counter charge, kept up an obstinate fight." But he quite forgets that there was a river between them, a river, too, of the nature that he had just himself described.³