The battle of Gaugamela (also known as Arbela) was one of the decisive battles fought by Alexander the Great during his invasion of Persia taking place on 1 October in 331 BC. Alexander had crossed the Hellespont in 334 BC with approximately 50,000 soldiers to start his conquest of the Persian Empire.
Darius’ forces had made it to the battlefield of Gaugamela before the Macedonians they used this advantage in order to prepare the battlefield. The Persians had brought scythed chariots to Gaugamela which required open, flat terrain. Darius had the ground prepared by removing impediments that would interfere with the chariots’ charge.
Darius sent a messenger to the Macedonian army before the battle with a third peace proposal he offered to give Alexander all the lands west of the Euphrates and a marriage bound between them. After the many defeats the Persians had faced at the hands of Alexander Persian morale must have been low. Alexander rejected the offer of peace.
Alexander’s forces were drawn up with the phalanx under the leadership of Craterus in the centre, the right wing consisted of the Hypaspist infantry, commanded by Nicanor (Parmenio’s son), the Companion cavalry commanded by Alexander and Philotas (Nicanor’s brother) and light cavalry. The left wing commanded by Parmenio were the Thessalian and Thracian horse. A second line of troops hidden from Persian view was made up of Greek troops and light infantry.
The ancient sources provide a variety of (unreliable) figures putting the Persian forces at about 1,000,000. Darius’ army at Gaugamela probably numbered between 50,000 and 80,000 troops, it certainly outnumbered the army of Alexander. Even though the Persian forces had the numerical advantage at Gaugamela, the Macedonians clearly had the troop quality advantage. The Macedonian forces had been in a consistent state of war for a number of years, in a disciplined mixed force.
As per Persian tradition Darius placed himself in the centre with his best infantry. He was surrounded by, on his right, the Carian cavalry, Greek mercenaries, and the Persian horse guards. In the right-centre he placed the Persian foot guards on both flanks were the cavalry. Bessus commanded the left flank with the Bactrians, Dahae cavalry, Arachosian cavalry, Persian cavalry, Susian cavalry, Cadusian cavalry, and Scythians. The Chariots were placed in front with a small group of Bactrians. Mazaeus commanded the right flank with the Syrian, Median, Mesopotamian, Parthian, Sacian, Tapurian, Hyrcanian, Caucasian Albanian, Sacesinian, Cappadocian, and Armenian cavalry.
On the day of the battle Darius forces had been kept up for the night, standing in battle formation, not wanting to be caught off guard. Conversely, Alexander ensured his troops were rested and well fed, delaying the onset of the battle in order to further fatigue the Persian army.
Although details of the battle are somewhat sketchy we know that Alexander’s forces marched forward with the phalanx set to engage the Persian infantry, whilst Alexander took his cavalry to the far right, Darius fell for Alexander’s ruse and tried to flank the Macedonian forces using his cavalry.
Arrian tells us:
“The Scythian cavalry rode along the line, and came into conflict with the front men of Alexander’s army; but he nevertheless still continued to march towards the right, and almost entirely got beyond the ground which had been cleared and levelled by the Persians. Then Darius, fearing that his chariots would become useless, if the Macedonians advanced into the uneven ground, ordered the front ranks of his left wing to ride round the right wing of the Macedonians, where Alexander was commanding, to prevent him from marching his wing any further. This being done, Alexander ordered the cavalry of the Grecian mercenaries under the command of Menidas to attack them. But the Scythian cavalry and the Bactrians, who had been drawn up with them, sallied forth against them, and being much more numerous they put the small body of Greeks to rout. Alexander then ordered Aristo at the head of the Paeonians and Grecian auxiliaries to attack the Scythians; and the barbarians gave way. But the rest of the Bactrians, drawing near to the Paeonians and Grecian auxiliaries, caused their own comrades who were already in flight to turn and renew the battle; and thus they brought about a general cavalry engagement, in which more of Alexander’s men fell, not only being overwhelmed by the multitude of the barbarians, but also because the Scythians themselves and their horses were much more completely protected with armour for guarding their bodies. Notwithstanding this, the Macedonians sustained their assaults, and assailing them violently squadron by squadron, they succeeded in pushing them out of rank.”
Darius launched his chariots into the Macedonian force, fearing that if he waited they would be of no use in the battle. As things turned out the chariots had very little effect anyway as Alexander’s forces had been prepared and opened ranks to allow them through where they were dealt with by the Hypaspists and the cavalry’s grooms. Alexander turned the companion cavalry and attacked the centre of the Persian line (still heavily engaged with the phalanx) and made a concerted push for Darius himself.
Darius, facing personal danger fled the field which sapped any remaining morale of the Persian forces who seeing their king flee routed. Alexander was not able to finish Darius as the Macedonian left flank needed to be supported or risked destruction. After the battle Darius made his intentions to flee further east clear but before he could he was murdered by one of his own Bessus, who was himself executed by Alexander in the following year.