hessalian cavalry,
commanded by Philippus, were next, and held the extreme left of the
whole army. The whole left wing was intrusted to the command of
Parmenio, who had round his person the Pharsalian regiment of cavalry,
which was the strongest and best of all the Thessalian horse regiments.

The centre of the second line was occupied by a body of phalangite
infantry, formed of companies which were drafted for this purpose from
each of the brigades of their phalanx. The officers in command of this
corps were ordered to be ready to face about if the enemy should succeed
in gaining the rear of the army. On the right of this reserve of
infantry, in the second line, and behind the royal horse-guards,
Alexander placed half the Agrian light-armed infantry under Attalus, and
with them Brison's body of Macedonian archers and Cleander's regiment of
foot. He also placed in this part of his army Menidas' squadron of
cavalry and Aretes' and Ariston's light horse. Menidas was ordered to
watch if the enemy's cavalry tried to turn their flank, and, if they did
so, to charge them before they wheeled completely round, and so take
them in flank themselves.

A similar force was arranged on the left of the second line for the same
purpose. The Thracian infantry of Sitalces were placed there, and
Coeranus' regiment of the cavalry of the Greek allies, and Agathon's
troops of the Odrysian irregular horse. The extreme left of the second
line in this quarter was held by Andromachus' cavalry. A division of
Thracian infantry was left in guard of the camp. In advance of the right
wing and centre was scattered a number of light-armed troops, of
javelin-men and bowmen, with the intention of warding off the charge of
the armed chariots.[51]

[Footnote 51: Kleber's arrangement of his troops at the battle of
Heliopolis, where, with ten thousand Europeans, he had to encounter
eighty thousand Asiatics in an open plain, is worth comparing with
Alexander's tactics at Arbela. See Thiers' _Histoire du Consulat_.]

Conspicuous by the brilliancy of his armor, and by the chosen band of
officers who were round his person, Alexander took his own station, as
his custom was, in the right wing, at the head of his cavalry; and when
all the arrangements for the battle were complete, and his generals were
fully instructed how to act in each probable emergency, he began to lead
his men toward the enemy.

It was ever his custom to expose his life freely in battle,