On October 1, 331 BC, Alexander the Great’s army defeated the Persian army led by Darius III at the Battle of Gaugamela to complete the conquest of the mighty Persian Empire.
It was an extraordinary victory achieved against a larger army. The superior tactics and the heroism displayed by the Macedonian cavalry led by Alexander carried the day.
Attempting to stop Alexander’s incursion into the Persian empire, Darius prepared a battleground on the Plain of Gaugamela, a village on the banks of the river Bumodus near Arbela—present-day Irbīl in northern Iraq—and deployed his troops to await Alexander’s advance.
Darius had the terrain of the prospective battlefield smoothed out so that his many chariots could operate with maximum effectiveness against the Macedonians.
His total forces greatly outnumbered those of Alexander, whose forces amounted to about forty thousand infantry and 7,000 cavalry. Modern historians say that “the odds were enough to give the most experienced veteran pause.”
Despite the overwhelming odds, Alexander’s army emerged victorious due to the employment of superior tactics and the clever usage of light infantry forces.
Alexander the Great’s campaign at the Persian Empire
Following the assassination of Phillip II, in 336 BCE, his father, Alexander, and his army left their home of Macedonia for the last time and set out on a campaign aimed at conquering the Persian Empire.
After crossing the Hellespont, Alexander traveled northward where he met and defeated the Persians under the leadership of the Greek mercenary Memnon at the Battle of River Granicus. As in future battles with Alexander, Darius and his generals continually underestimated the abilities of the young Alexander. He was considered by many—even those in Greece—to be nothing more than an upstart veteran.
Alexander moved southward along the coast of Asia Minor to Halicarnassus, where he defeated Memnon for the second time. Finally, after waiting for over a year, Alexander and his forces met Darius at Issus in November of 333 BCE where, again, the Persians suffered defeat.
Alexander then captured Darius’ family—his mother, wife, and daughters. Wishing to avoid further conflict and with hopes that he would regain his family, Darius offered Alexander half of his kingdom and even his daughter’s hand in marriage. However, Alexander rejected the offer by simply saying there could never be two suns as it would upset the world order.
Alexander challenged the Persian king to once again face him in battle. Following the battle at Issus, Alexander continued his campaign and moved along the Mediterranean coast, capturing the coastal city of Tyre in a seven-month siege.
As he traveled southward, he was welcomed in both Jerusalem and Egypt, for they had felt the wrath of the Persian army. After laying out the plans for the future city of Alexandria and visiting the temple at Siwa, Alexander prepared for his next military engagement with Darius.
Victory at Gaugamela
Alexander had planned to march straight to Babylon, but when he learned of Darius’ presence at Gaugamela, he instead turned northward to meet and battle the Persian king. He realized a victory at Gaugamela meant the conquest of all of Persia, including Babylon, Persepolis, and Susa.
Darius who had learned his lesson at the Battle of Issus had carefully chosen Gaugamela for his next battle against Alexander. This time, his army was quite more advanced, having brought together men from all over his empire—even Indian mercenaries.
Estimates of his army vary from fifty thousand to almost a million. The terrain of Gaugamela was also significant, as it was much wider, so he could deploy his cavalry more effectively. For Darius it was clear that the size of his army and the terrain gave him a significant advantage against Alexander.
Alexander’s well-trained army of about forty thousand faced Darius’ massive battle line and organized for the attack, charging the left of the Persians’ line with archers, javelin throwers, and cavalry while defending against Darius’ outflanking cavalry with reserve flank guards.
While Alexander was challenging the Persians on the right, Darius sent his scythed chariots towards the center, a move that failed to have the effect Darius had hoped. As the chariots approached, the phalanx merely opened ranks, allowing the chariots to pass through. Alexander and his personal cavalry immediately wheeled half left and penetrated this gap and then wheeled again to attack the Persians’ flank and rear.
Alexander, spying Darius, seized upon the opportunity and threw a spear at the shocked king, missing him by merely a few inches. Just like at Issus, Darius realized that victory was hopeless and fled. Panic then spread through his entire army, which began a headlong retreat.
Plutarch, in his Life of Alexander, spoke of Darius’s flight:
Darius now seeing all was lost, that those who were placed in front of him were broken and beat back upon him, that he could not turn or disengage his chariot without great difficulty, the wheels being clogged and entangled among the dead bodies…was glad to quit his chariot and his arms, and mounting, it is said, upon a mare that had been taken from her foal, betook himself to flight.
Darius was later murdered by one of his satraps, and Alexander conquered the Persian capital of Babylon. The victory signified the end of the Persian Empire founded by Cyrus II, commonly known as Cyrus the Great, and made Alexander the master of southwest Asia.