Which Persian king did Alexander defeat at the Battle of Issus?

Alexander defeated the Persian king Darius III at the Battle of Issus. Fought on 5 November 333 BC in southern Anatolia, the battle was the first direct encounter between Alexander and Darius during Alexander’s invasion of the Achaemenid Empire.

The narrow coastal plain near Issus limited the Persian army’s numerical advantage. Alexander attacked aggressively while his Macedonian phalanx and allied troops held the line. When Alexander’s cavalry threatened Darius’s position, the Persian king fled, causing much of his army to collapse. Darius left behind his family and royal baggage, which Alexander captured.

Issus was Alexander’s second major battle against Persia, following the Battle of the Granicus in 334 BC. It is often confused with Gaugamela, where Alexander defeated Darius again in 331 BC. Darius escaped from Issus but was later killed by the Persian satrap Bessus.