At which battle did Alexander decisively defeat Darius III in 331 BC?

The Battle of Gaugamela was the battle in which Alexander the Great decisively defeated Darius III in 331 BC. It was the second and final direct battle between the Macedonian king and the Persian ruler.

The battle took place on 1 October 331 BC near Gaugamela, probably close to modern Erbil in Iraqi Kurdistan. Darius prepared a broad, level battlefield that allowed his much larger army and scythed chariots to manoeuvre. Alexander’s force was heavily outnumbered, but its disciplined infantry and coordinated cavalry were decisive.

Alexander advanced obliquely toward the Persian left, drawing parts of Darius’s line out of position. When a gap opened near the Persian centre, Alexander personally led the Companion cavalry through it. Darius fled, and although the Persian army continued fighting elsewhere, the loss of its king’s position turned the battle into a decisive Macedonian victory.

Granicus and Issus were earlier victories over Persian forces; Hydaspes was fought later in India against King Porus.