Battle of Gaugamela

The Battle of Gaugamela, also called the Battle of Arbela, was fought on 1 October 331 BCE on the plains of northern Mesopotamia, near modern Erbil in Iraq. Alexander the Great defeated the Persian king Darius III for the second and last time. The battle broke the military power of the Achaemenid Empire and opened its heartland, with the great royal cities of Babylon, Susa and Persepolis, to Macedonian conquest.

Alexander had begun his campaign against Persia by crossing into Asia in 334 BCE and beating Persian forces at the Granicus River. In 333 BCE he defeated Darius himself at Issus, capturing the king's family. He then spent nearly two years taking the coast of the Levant, including a long siege of Tyre, and entering Egypt. Darius used the time to raise a new army from the eastern provinces of his empire. He reportedly offered Alexander large concessions of territory in exchange for peace, which Alexander refused. In 331 BCE Alexander marched east, crossed the Euphrates and the Tigris, and found the Persian army waiting for him.

Darius chose a broad, level plain where he could use his numerical advantage. He had the ground cleared so that his scythed chariots could charge, and he deployed elephants as well. Ancient writers gave fantastic figures for the Persian army, up to a million men; modern estimates range from about 50,000 to 250,000, still far larger than Alexander's force. The Macedonian army, including Greek allies and mercenaries, probably numbered about 40,000 infantry and 7,000 cavalry.

Expecting to be outflanked, Alexander arranged his army with a second line behind the first that could turn to face an attack from the rear. He led the right wing himself, with his Companion cavalry, while his veteran general Parmenion held the left. As the battle began, Alexander moved his line obliquely towards the right, drawing Persian cavalry after him and pulling the Persian line out of shape. The scythed chariots were largely neutralised by light troops, who struck at the drivers and horses or let the chariots pass through gaps in the ranks.

When a gap opened in the Persian centre, Alexander turned and led a wedge of cavalry and infantry straight towards Darius. The Persian king fled, as he had at Issus, and his centre gave way. Meanwhile the Macedonian left under Parmenion was under heavy pressure, and Persian horsemen broke through to the baggage camp. Alexander broke off his pursuit to help, and by nightfall the Persian army had dissolved. Casualty figures in the ancient accounts are unreliable, but Persian losses were clearly far heavier than Macedonian ones.

Darius escaped into the Iranian highlands, hoping to raise yet another army. Alexander instead marched south: Babylon surrendered without a fight, Susa yielded its treasury, and Persepolis was occupied and, in 330 BCE, its palaces burned. That summer Darius was murdered by Bessus, one of his own satraps, as Alexander closed in. Alexander then presented himself as the successor of the Achaemenid kings.

Gaugamela is often studied as a model of how a smaller, disciplined army can defeat a larger one through manoeuvre and the decisive use of a striking force. Politically, it marked the end of two centuries of Achaemenid rule over the Near East and the beginning of a Greek-speaking ruling class across the region, which lasted long after Alexander's death.

Our 400 BCE map shows the Achaemenid Empire at its height. The 323 BCE map shows the Macedonian Empire that replaced it, as it stood when Alexander died.