The epic of Alexander the Great brought the character into the pantheon of the great conquerors in history. The confrontation of Gaugamèles constitutes the decisive battle, that which assures him definitively the throne of Persia. Darius III, the king of the Achaemenid dynasty, the unrecognized and unfortunate adversary of the young king of Macedonia, has already been defeated at Issus. The two armies, very different in many aspects, each benefit from assets that could guarantee them a lasting and definitive success on the battlefield. Gaugamèles represents in this respect the test of truth for two dissimilar military organizations, for two contrasting tactical systems and for two styles of command...