How Alexander the Great Ended the Achaemenid Empire at the Battle of Gaugamela

Tristan Hughes

4 mins

01 Oct 2018

On 1 October 331 BC, Alexander the Great won a definitive victory at Gaugamela against the Persian empire. Alexander’s charismatic leadership and brilliant use of cavalry secured his immortality, and signalled the end for his wily foe, the Persian ruler Darius III.

Alexander the Great (356-323 BC) was the son of Philip, King of Macedon, a kingdom just north of Greece. He first saw battle in his father’s campaigns against the Greek states including Sparta and Athens.

Upon the death of his father, Philip II, he turned his eyes towards the huge and powerful Persian Empire, which then extended from modern-day Libya to the north of India.

Alexander marched across the Hellespont into Asia and met with initial success against the Persians in a series of battles and sieges, securing his reputation as a superb commander.

Alexander the Great formed a huge empire from the Adriatic to the Punjab, with one of his most important conquests being Egypt. Discover some of its secrets in the documentary Egypt: What Lies Beneath on HistoryHit.TV. Watch Now

Following his stunning victory at Issus and the completion of the gruelling siege of Tyre, Macedonian invader Alexander controlled much of the Middle East and Egypt. However, his enemy, Darius III, remained at large and was raising a huge army in the eastern part of his empire.

Truce falls flat

Alexander rejected Darius’ attempts to negotiate a truce, rejecting even the offer of becoming a co-ruler of Asia, insisting that there could be only one king of Asia, and instead advanced towards Babylon, taking a northerly route across both the Euphrates and the Tigris.

Darius rode out from Babylon to face Alexander. After being enclosed by a narrow battlefield at Issus two years before, Darius chose a large flat battlefield in present-day Iraq with few obstacles and little cover, and proceeded to flatten it further for his war chariots.

Bust of Alexander the Great from the Hellenistic era.

Modern estimates put his army at 50-100,000, including War Elephants and 10,000 of the famous Persian Immortals. Alexander’s army was around 47,000 strong, including 7,000 cavalry.

The battle

Despite being outnumbered, Alexander remained confident and devised an ingenious battle plan. With himself at the helm, Alexander led his elite Companion cavalry far out to the right. Fearing that Alexander intended to outflank his force, Darius ordered his own cavalry on the left to check Alexander’s movements and then encircle the Macedonian army.

Meanwhile the heavy Macedonian infantry engaged the Persian centre – which included an elite Persian regiment called the Immortals – in phalanx formation.

This was exactly what Alexander had hoped his foe would do. Both by drawing out the Persian cavalry and the advance of Darius’ crack infantry, a vulnerable gap in the Persian line now presented itself to Alexander. Slowly he filtered his best troops back from the right, forming a giant wedge and striking at the newly-created gap at the heart of the Persian line, straight at Darius. Losing his nerve, Darius turned tail and fled, just as he had at Issus.

A diagram of the key events of the Battle of Gaugamela.

As soon as Darius fled, so too did many of the Persians fighting nearby. The outflanking force on the right, too, was successfully repulsed.

On the left flank of Alexander’s army, however, a different story was occurring. This part of Alexander’s army, under the command of Parmenion, his second in command, was beginning to buckle, overwhelmed by the sheer mass of Persian cavalry opposing them.

Hearing of this struggle, Alexander turned his horsemen around and charged into the back of the Persian force, leaving Darius free to escape. After a fierce fight the Persian cavalry was routed and Alexander’s victory was complete.

A Flemish tapestry of the Battle of Gaugamela from the first half of the 18th century.

The aftermath

The victory brought the Macedonian army huge amounts of plunder from Darius’ camp and low casualties of below a thousand, while Persian casualties have been estimated to have been as high as 40,000.

Alexander subsequently marched his army to Babylon where he was received as the legitimate King of Asia.

Darius fled yet further east in an attempt to raise another army from his Satraps but one of them, Bessus, murdered him. Alexander was said to have been saddened by such an end for his greatest enemy and gave Darius a lavish burial at the Persian capital of Persepolis, as well as capturing and executing Bessus.

With his death most historians agree that the Persian Empire, the world’s first superpower, was no more, replaced by the growing empire of the victor of Gaugamela. Alexander would later go on to invade parts of India, leading to his untimely death at the age of 33.