In this way had Alexander marshalled his army in front; but he also posted a second array, so that his phalanx might be a double one.[410] Directions had been given to the commanders of these men posted in reserve, to wheel round and receive the attack of the foreigners, if they should see their own comrades surrounded by the Persian army. Next to the royal squadron on the right wing, half of the Agrianians, under the command of Attalus, in conjunction with the Macedonian archers under Briso’s command, were posted angular-wise (_i.e._ in such a way that the wings were thrown forward at an angle with the centre, so as to take the enemy in flank) in case they should be seized anyhow by the necessity of folding back the phalanx or of closing it up (_i.e._ of deepening it by countermarching from front to rear). Next to the archers were the men called the veteran mercenaries, whose commander was Cleander. In front of the Agrianians and archers were posted the light cavalry used for skirmishing, and the Paeonians, under the command of Aretes and Aristo. In front of all had been posted the Grecian mercenary cavalry under the direction of Menidas; and in front of the royal squadron of cavalry and the other Companions had been posted half of the Agrianians and archers, and the javelin-men of Balacrus who had been ranged opposite the scythe-bearing chariots. Instructions had been given to Menidas and the troops under him to wheel round and attack the enemy in flank, if they should ride round their wing. Thus had Alexander arranged matters on the right wing. On the left the Thracians under the command of Sitalces had been posted angular-wise, and near them the cavalry of the Grecian allies, under the direction of Coeranus. Next stood the Odrysian cavalry, under the command of Agatho, son of Tyrimmas. In this part, in front of all, were posted the auxiliary cavalry of the Grecian mercenaries, under the direction of Andromachus, son of Hiero. Near the baggage the infantry from Thrace were posted as a guard. The whole of Alexander’s army numbered 7,000 cavalry and about 40,000 infantry. CHAPTER XIII. THE BATTLE OF ARBELA.