Battle Of Gaugamela
For good cause, the Battle of Gaugamela, also known as the Battle of Arbela, which is now Erbil in Iraq, is occasionally referred to as the most significant battle in Alexander's military career. It was the pivotal battle of the Macedonian war in Persia, fought in October 331 BC.
The outcome may have seemed certain at the time, but the Persian contingent, which included battle-tested troops of scythed chariots and war elephants, outnumbered Alexander's forces by at least a 2:1 margin. The Persians also selected the open field of combat because it greatly suited their particular fighting strategy.
Although the exact specifics of the conflict are difficult to discover because it took place a long time ago, later accounts reveal that Alexander's cavalry ultimately determined the victory. In total, 700 Macedonian warriors died that day, as opposed to more than 20,000 Persian soldiers.
Darius himself was compelled to leave the area of combat, albeit one of his own province governors later assassinated him. The conflict brought the mighty Persian empire to an abrupt end, opening the door for further Hellenization of West Asia.
Date: 1 October 331 BC
Location: Probably Tel Gomel (Gaugamela) near Erbil, modern Iraqi Kurdistan
Result: Macedonian victory
Territorial changes: Alexander gains Babylon, half of Persia and all other parts of Mesopotamia