Gaugamela, 331 BC, in Arrian's account and a Babylonian diary
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TL;DR — At Gaugamela on October 1, 331 BC, Alexander’s charge broke Darius III’s army; Arrian says Darius fled first, a Babylonian diary that his troops deserted him.
The battle of Gaugamela, fought on October 1, 331 BC east of the Tigris, ended the Persian king Darius III’s last great army. The fullest account is Arrian’s, written centuries later: Alexander drew the Persian line to the right until it opened, then charged at Darius, who “was the first to turn and flee.” A Babylonian astronomical diary written at the time tells it differently, and the historian Jona Lendering warns, “We simply have no idea what happened.”
Quick facts
- When
- October 1, 331 BC
- Where
- Gaugamela, on a plain east of the Tigris, in what is now northern Iraq
- Who
- Alexander III of Macedon; Darius III of Persia
- Outcome
- Darius's army broke and he fled east; Babylon and Susa fell to Alexander that autumn, and Darius was murdered the next year
How many men?
Arrian gives Alexander’s army as “7,000 cavalry and about 40,000 infantry.” For Darius he gives a figure he does not vouch for: the Persian army “was said to contain 40,000 cavalry, 1,000,000 infantry, and 200 scythe-bearing chariots.”
The other ancient writers disagree. Diodorus says Darius marched out of Babylon with “eight hundred thousand infantry and no less than two hundred thousand cavalry.” A note in the Chinnock translation of Arrian collects the rest: Curtius gives 200,000 infantry and 45,000 cavalry, Justin 400,000 foot and 100,000 horse, and Plutarch “a million of men.” The infantry figures alone range from 200,000 to a million.
A plain made for chariots
Darius chose his ground after his defeat at Issus. He camped at Gaugamela “in a district everywhere level,” Arrian writes, “for whatever ground thereabouts was unlevel and unfit for the evolutions of cavalry, had long before been levelled by the Persians, and made fit for the easy rolling of chariots and for the galloping of horses.” Some of his advisers had persuaded him that he lost at Issus because the field there was narrow.
The march to the right and the gap
Alexander did not fight on that prepared ground if he could help it. “Alexander led his own army more towards the right,” Arrian writes, “and the Persians marched along parallel with him, far outflanking him upon their left.” He kept moving right until he “almost entirely got beyond the ground which had been cleared and levelled.” Darius, “fearing that his chariots would become useless,” sent cavalry around Alexander’s right wing to stop him.
That move opened the Persian line. “When the Persians had made a break in the front line of their army,” Arrian continues, “Alexander wheeled round towards the gap, and forming a wedge as it were of the Companion cavalry and of the part of the phalanx which was posted here, he led them with a quick charge and loud battle-cry straight towards Darius himself.”
Who fled first?
In Arrian’s version Darius broke. When the Macedonian cavalry and phalanx pressed in, “all things at once appeared full of terror to Darius, who had already long been in a state of fear, so that he was the first to turn and flee.”
The Babylonian Astronomical Diary, quoted by Lendering, records the same day from the other side: “The troops abandoned their king and headed back to their cities. They fled to the lands in the east.” Lendering points out that “this contradicts the Greek source that is often accepted as the best, Arrian,” and that reversing the sentence to make it fit “will not make Arrian right.”
An eclipse before the battle
Lendering’s own reading puts the decision before the fighting. A lunar eclipse had occurred, and “the omens were extremely unfavorable: the precise circumstances predicted a defeat for the ruler of Babylonia and Persia.” In his view this “proved to be a self-fulfilling prophecy.” On the battle itself, he concludes, “What actually happened lies concealed for ever in the dust clouds of the battlefield.”
What followed is not in doubt. Alexander reached Babylon and Susa that autumn and spent the winter at Persepolis. Darius was murdered in 330 BC, ending the line of kings that Lendering traces to Cyrus the Great’s victory over the Medes in 550 BC.
Key facts
- Gaugamela was fought on October 1, 331 BC (Lendering).
- Arrian gives Alexander 7,000 cavalry and about 40,000 infantry (Arrian 3.12).
- Arrian says Darius’s army “was said to contain” 40,000 cavalry, 1,000,000 infantry and 200 scythed chariots (Arrian 3.8).
- Diodorus gives 800,000 infantry and 200,000 cavalry; Curtius 200,000 infantry (Diodorus 17.53; Chinnock’s note).
- Arrian says Alexander charged through a gap in the Persian line at Darius, who fled first (Arrian 3.13–14).
- The Babylonian Astronomical Diary says Darius’s troops abandoned him (Lendering).
FAQ
When was the Battle of Gaugamela?
On October 1, 331 BC, on a plain east of the Tigris.
How big were the armies at Gaugamela?
Arrian gives Alexander about 47,000 men. Figures for Darius range from Curtius's 200,000 infantry to the million Arrian reports he "was said" to have.
How did Alexander win at Gaugamela?
In Arrian's account, he moved his army to the right until the Persian cavalry, sent to stop him, opened a gap; he then led a wedge of Companion cavalry and infantry through it at Darius.
Did Darius run away at Gaugamela?
Arrian says Darius was the first to flee. The Babylonian Astronomical Diary, written at the time, says his troops abandoned him.
Why did Darius choose the plain at Gaugamela?
Arrian writes that the Persians leveled the ground for chariots and cavalry, after advisers persuaded Darius that the narrow field at Issus had cost him that battle.
Sources
- Arrian, The Anabasis of Alexander, translated by E. J. Chinnock (1884), Book 3, Project Gutenberg
- Diodorus Siculus, Library of History 17.53, translated by C. Bradford Welles (1963), LacusCurtius, University of Chicago
- Jona Lendering, "Gaugamela (331 BCE)," Livius.org
- Jona Lendering, "Alexander the Great," Livius.org
- Jona Lendering, "Achaemenids," Livius.org
Cite this article
- APA
- Song Letter. (2026, October 11). Gaugamela, 331 BC, in Arrian's account and a Babylonian diary. Our Earth's History. https://ourearthshistory.com/europe/classical/gaugamela-half-an-army/
- Chicago
- Song Letter. “Gaugamela, 331 BC, in Arrian's account and a Babylonian diary.” Our Earth's History, October 11, 2026. https://ourearthshistory.com/europe/classical/gaugamela-half-an-army/.
- MLA
- Song Letter. “Gaugamela, 331 BC, in Arrian's account and a Babylonian diary.” Our Earth's History, 11 Oct. 2026, https://ourearthshistory.com/europe/classical/gaugamela-half-an-army/.
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