5 – Battle of Issus (333 BC)
Given the extraordinary leadership ability shown by Alexander the Great during his conquests, you could say that the Achaemenid Empire was doomed as soon as the Macedonian general decided to include it in his list of conquests. Alexander had already defeated the Persians at Granicus and Halicarnassus, and by now, the Persian King Darius III believed his empire was at grave risk. This was a stark reversal of his attitude a year earlier when Alexander invaded. Darius believed the youthful invader was no real threat then but now knew the strength of the enemy.
Ancient estimates of the Persian strength are greatly overestimated; modern historians believe that Darius had an army of up to 108,000 and not the 600,000 reported by Arrian. Nonetheless, he still outnumbered Alexander who brought 40,000 men to the Battle of Issus. Darius had the advantage of choosing the battlefield, so he picked an area where a river ran through the middle, the Gulf of Issus to the West and mountains in the East.
Darius divided his forces into two staggered lines stretching to the mountains from the Gulf. The Persian king surrounded himself with the royal bodyguards and these men were flanked by around 30,000 Greek mercenaries. Also, Darius had his mobile light infantry to call upon while he placed his entire cavalry force on the right flank. Alexander countered by sending a relatively small force into the mountains to handle the enemy infantry. Ultimately, Alexander’s army stretched the length of the river.
On a wet and cold day, the armies faced off at the River Penarus. It was the ideal location for Alexander as it significantly reduced the mobility of the Persians. Not only did Darius refuse to listen to one of his best generals, the Greek Charidamus, who advised the king to split up his forces and allow him to face Alexander, but he also executed him!
Regarding the battlefield, Darius clearly chose poorly because his army was hampered from the start yet Alexander could use his tried and trusted Phalanx formation. Darius tried and failed to break through the enemy right flank, and Alexander used his cavalry to smash through the Persian left. Alexander saw Darius and tried to kill him, but the Persian king fled the battlefield on a chariot. At that stage, the Persian right flank was holding firm, but once they saw their leader flee, the men lost heart, and the line disintegrated.
Approximately 20,000 Persians died at Issus compared to 7,000 of Alexander’s men. Alexander found Darius’ wife and child in a tent, and while he didn’t harm them, he would not return them even though the Persian king offered half of his kingdom. Instead, Alexander wanted to meet his rival in battle again and got his wish with a significant win at Gaugamela in 331 BC.