Immediately he prepared for battle.

Passing a force of horse and foot across the stream in his front, to keep his adversary in check if he advanced too rapidly, he drew up his best troops along the line of the river in a continuous solid mass, the ranks of which must have been at least twenty deep.
Thirty thousand Greek mercenaries formed the centre of the line, while on either side of them were an equal number of Asiatic "braves"-- picked probably from the mass of the army.

Twenty thousand troops of a lighter and inferior class were placed upon the rough hills on the left, the outskirts of the Amanian range, where the nature of the ground allowed them to encircle the Macedonian right, which, to preserve its ranks unbroken, kept the plain.

The cavalry, to the number of 30,000, was massed upon the other wing, near the sea.
The battle began by certain movements of Alexander against the flank force which menaced his right.

These troops, assailed by the Macedonian light-armed, retreated at once to higher ground, and by their manifest cowardice freed Alexander from all anxiety on their account.