The Battle of Gaugamela, 1 October 331 BCE

After losing the Battle of Issus in 333 BCE, Darius III fled the battlefield in such haste that his army headquarters staff was captured, including the royal family, his wife and two daughters. He retreated eastward into the Achaemenid Persian Empire’s heartlands, where he could set about raising new armies to face Alexander’s anticipated advance. Meanwhile, after the Battle of Issus, Alexander consolidated his control of most of Asia Minor, the Levantine coast and Egypt, the latter surrendering at his approach. After this was achieved Alexander continued his campaign in the spring of 331 BCE, marching northeast across Syria, crossing the Euphrates and Tigris rivers and facing little resistance. Darius, who was following Alexander’s progress, chose to deploy his army of around 100,000 men on the Plain of Gaugamela in what is now northern Iraq. Alexander’s army of 47,000, heavily outnumbered, deployed to meet Darius for the second battle with the Persian king. Alexander’s army was by now battle hardened and experienced; Darius relied more on overwhelming numbers, made up of some professional units and many less well trained troops. The Macedonians began with an oblique advance toward the Persian centre and, despite the odds, the Macedonians and their allies demonstrated their superior tactics, gradually defeating the less flexible Persians. Again Darius fled the battlefield, only to be murdered by Bessus, satrap of Bactria. Alexander executed Bessus for this fearful deed in 329 BCE.