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# Battle of Gaugamela

## Overview
The Battle of Gaugamela (1 October 331 BCE) was the decisive battle in which Alexander the Great defeated the Persian King Darius III, effectively ending the Achaemenid Persian Empire. @t[=331 BCE] The date is confirmed by Babylonian astronomical diaries. [^3]

## Key Facts
- Date: 1 October 331 BCE @t[=331 BCE]
- Location: Gaugamela, near the Jomel River east of Mosul (exact site uncertain; near modern Erbil/Mosul region, Iraq) [^3]
- Belligerents: Macedon vs. Persian Empire
- Commanders: Alexander the Great vs. Darius III; Persian right commanded by Mazaeus
- Result: Decisive Macedonian victory [^1]

## The Battle
- Alexander: ~47,000 troops (including ~7,000 cavalry [^3]); Darius: ancient sources give wildly varying figures (40,000–200,000 cavalry; 200,000–1,000,000 infantry) regarded as unreliable by modern scholars [^3]
- Darius leveled the battlefield to give his scythed chariots and cavalry a decisive advantage; some Persian forces were equipped with Macedonian-style sarissae [^3]
- A lunar eclipse on 20 September was interpreted as an omen of Darius' defeat [^3]
- Alexander used an oblique advance to the right, threatening to outflank Darius' left and leave the prepared ground
- Darius launched scythed chariots and sent his best cavalry left, creating a gap near his center
- A wedge of Macedonian cavalry poured through the gap while the phalanx attacked frontally, both driving toward Darius
- Darius fled; the Persian army collapsed, though Persian and Indian troops briefly penetrated the Macedonian camp [^3]

## Aftermath
- Mazaeus, who commanded the Persian right, surrendered Babylon to Alexander ~20 days after the battle and was appointed its satrap [^3]
- Alexander captured Susa and Persepolis (by January 330 BCE) @t[=330 BCE] [^3]
- Darius III fled to Ecbatana, then was murdered by his own satrap Bessus (330 BCE) @t[=330 BCE] [^1]
- Marked the end of the Achaemenid dynasty after ~220 years [^2]

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[^1]: Arrian, *Anabasis of Alexander* 3.8–15
[^2]: Heckel, W. *The Conquests of Alexander the Great* (Cambridge, 2008)
[^3]: Badian, Ernst. "Gaugamela." *Encyclopaedia Iranica* Vol. X, Fasc. 3 (2000, updated 2015). https://www.iranicaonline.org/articles/gaugamela/ — citing Sachs, A.J. and Hunger, H. *Astronomical Diaries and Related Texts from Babylonia* (Vienna, 1988), pp. 178–79 for the date; Arrian 3.12.5 for cavalry numbers; Diodorus 17.53.1 for sarissae; Bosworth, A.B. *Conquest and Empire* (Cambridge, 1988) pp. 76–85
