a hill (modern name, Tell Gōmel) and settlement (near modern Gōmel-sū) in Mesopotamia, northwest of the city of Arbela. On Oct. 1, 331 B.C., a decisive battle took place near Gaugamela between Alexander of Macedonia (40,000 infantry, 7,000 cavalry) and the Persian king Darius III Codomannus (60,000-80,000 infantry, up to 15,000 cavalry, 200 war chariots, and 15 battle elephants). Smashing the Persians’ covering force on the Euphrates River, Alexander moved toward Gaugamela, where the Persian army had taken position. The Persians attacked both flanks of the Macedonians and broke through their left flank to the camp, where the Macedonian infantry stopped them. Alexander struck a decisive blow to the left wing of the Persian army with the right flank of his army, consisting mainly of crack cavalry. He smashed the Persian left wing and broke through to the rear of the attacking Persian right wing. The Persian troops fled, and the Macedonian cavalry pursued them for 50 km.