Philip II of Macedon began an attack on the Achaemenid Empire after the death of Artaxerxes (Artaxšaçrā) III Ochus in 338 BCE. His son, Alexander the Great, renewed the attack beginning in 334 BCE. Darius III was already an old man and he was defeated by Alexander at Gaugamela (331 BCE). Alexander proceeded to capture the capital city of Susa. The Achaemenid Empire was now in his hands.