Aristarchus could ask him: "Won't you do something of the sort, oh Son of Zeus?" But the crazy notion was, nevertheless, present henceforth in his brain, ready to be inflamed by wine or flattery.
Next spring (331 B.C.) he returned to Tyre, and marched thence round towards Assyria, leaving the Syrian desert on his right. Near the ruins of forgotten Nineveh he found a great Persian army, that had been gathering since the battle of Issus, awaiting him. It was another huge medley of contingents, and it relied for its chief force upon that now antiquated weapon, the war chariot. Of these Darius had a force of two hundred, and each chariot had scythes attached to its wheels and to the pole and body of the chariot. There seem to have been four horses to each chariot, and it will be obvious that if one of those horses was wounded by javelin or arrow, that chariot was incapacitated. Against broken footmen or a crowd of individualist fighters such vehicles might be formidable; but Darius began the battle by flinging these instruments against the cavalry and light infantry. Few reached their objective, and those that did were readily disposed of. There was some manœuvring for position. The well-drilled Macedonians moved obliquely across the Persian front, keeping good order; the Persians, following this movement to the flank, opened gaps in their array. Then suddenly the disciplined Macedonian cavalry charged at one of these torn places and smote the centre of the Persian host. The infantry followed close upon their charge. The centre and left of the Persians crumpled up. For a while the light cavalry on the Persian right gained ground against Alexander's left, only to be cut to pieces by the cavalry from Thessaly, which by this time had become almost as good as its Macedonian model. The Persian forces ceased to resemble an army. They dissolved into a vast multitude of fugitives streaming under great dust clouds and without a single rally across the hot plain towards Arbela. Through the dust and the flying crowd rode the victors, slaying and slaying until darkness stayed the slaughter. Darius led the retreat.
Such was the battle of Arbela. It was fought on October the 1st, 331 B.C. We know its date so exactly, because it is recorded that, eleven days before it began, the soothsayers on both sides had been greatly exercised by an eclipse of the moon.