historiandaily:

“For a short time there ensued a hand-to-hand fight; but when the Macedonian cavalry, commanded by Alexander himself, pressed on vigorously, thrusting themselves against the Persians and striking their faces with their spears…all things together appeared full of terror to Darius, who had already long been in a state of fear, so that he was the first to turn and flee.” -Arrian of Nicomedia

October 1, 331 BC- Alexander the Great inflicts his final defeat on Darius III and his Persian army at the Battle of Gaugamela. As Darius fled east to raise another army, he was murdered by Bessus, one of his satraps, ending the 220 year old Achaemenid Empire. 

Picture- Battle of Gaugamela, unknown artist, 18th century