On 1 October 331 BC Alexander the Great defeated the army of the Persian king Darius III on the plain of Gaugamela, northeast of Nineveh in today's northern Iraq. Darius had chosen open ground to suit his larger cavalry and his scythed chariots, but a single charge by Alexander through a gap in the Persian line broke the center and Darius fled. The victory ended the Achaemenid Empire as a power and left Alexander master of southwest Asia.
How we know the date
The day is fixed by the sky. A total eclipse of the moon was seen on the evening of 20 September 331 BC, when Alexander's army had crossed the Tigris, and the battle followed eleven days later. A Babylonian astronomical diary, written by officials of the Esagila temple in Babylon and now in the British Museum, records the battle under the 24th day of the sixth month, which corresponds to 1 October. Like all ancient dates, this one is given in the Julian calendar.1
The diary is the only account written at the time. It says that the king's troops deserted him and went back to their cities, while the Greek and Roman historians, writing much later, say that Darius fled from the field.2
The battle in brief
Darius had leveled the plain in front of his line so his chariots could run, and he placed himself in the center with cavalry under Bessus on his left and Mazaeus on his right. The ancient figures for the size of his army vary and some are fantastic, but every source agrees that the Persians outnumbered the Macedonians. Alexander led the Companion cavalry on his right and edged away from the leveled ground; his archers and javelin men shot down most of the charioteers, and the infantry opened ranks to let the rest through.3
When the fighting on the Persian left opened a gap, Alexander wheeled into it with his cavalry and part of the phalanx, the Persian center broke, and Darius led the flight. On the other wing Parmenio was hard pressed by Mazaeus, and Alexander broke off the pursuit to help him. Persian losses were heavy. Arrian gives only 100 Macedonian dead, while Diodorus and Curtius give higher figures. Darius escaped east and was murdered by Bessus the next year.4
The full story of the campaign, the ground and the charge is in our article on the Battle of Gaugamela. The battle that came before it is told in our article on Issus, and the man who won both in our biography of Alexander the Great.5
Also on this day
- 1756: Battle of Lobositz. At Lobositz in northern Bohemia, Frederick the Great's Prussians fought Count Browne's Austrians, who were marching to aid the Saxons trapped at Pirna, in the first land battle of the Seven Years' War.
