The Battle of Gaugamela, 331 BC, was a decisive victory in the conquest of the Persian Empire by Alexander the Great, when he defeated the Persian king Darius III. after this battle, the Achaemenid Empire ceased to exist.
Before the Battle
The Macedonian king Alexander the Great started his conquest of Asia by passing through the Hellespont Strait in the spring of 334 BC. First, he defeated Persian satraps, at the Battle on the Granicus River. With that he captured all of Asia Minor. One year later, in the Battle of Issus, he managed to defeat a Persian army led by the Persian king Darius III. The Persian Emperor had to flee to the center of his Empire to try to collect a new army. After that, Alexander captured Syria and Egypt. Alexander first had to destroy the Persian Navy that controlled the sea. The Persian Emperor did not aspire to regain his possessions quickly, but he adopted a new strategy; lure the enemy deep into his territory, wear them down and then finish the enemy. The Persian Emperor tried to propose a peace and divide the Empire, but he was declined.
In 331 BC, Alexander made the necessary preparations and secured his rear. He was ready to lead the army into the center of the Persian Empire. The Persian satrap Mazes left his land undefended, leaving it to the Macedonians. On the Tigris, the Persians didn’t attack Alexander, and he, with no opposition, managed to take a large part of the Empire. After the crossing of the Tigris, Alexander was confronted with a large Persian army, led by Darius on the plain, near the town of Arbela, at the intersection of strategic roads that connected the Empire. On October 1, 331 BC, a battle was fought at Gaugamela, that concluded with the end of the 200-year-old Persian Empire that stretched from the Aegean Sea in the west to India in the east.
Forces
Alexander’s army numbered 47,000 men. The Macedonian army was put in the same battle situation as in the past battles. Darius’ troops numbered 45,000 cavalry and 200,000 infantry according to the ancient sources, while the modern estimates are much smaller.
The Battle
When the opposing armies met on the battlefield, Alexander had given an order to his troops to rest in camp. The Persians, fearing a Macedonian surprise attack, stood tensely in battle formation all day and night. In the morning, they were weakened with fatigue and fear of the Macedonian army.
The battle started with the attack of Persian chariots, in which the Persian Emperor Darius had placed his hopes. The Macedonians were prepared for their attack. The horses that were pulling the chariots were distracted by the screaming and noise raised by the phalanxes, they turned back and ran through their own troops. In the next attack wave, the horses and drivers were killed by the light Macedonian infantry that stood in the main formation. Chariots that managed to break into the ranks of the Macedonian infantry were killed by long Macedonian spears. Only a few chariots succeeded in sowing any death in the Macedonian ranks.
Mazey, the Persian commander, managed to get around the left flank of the Macedonian army and squeeze between the lines of cavalry. Parmenion (Macedonian commander) fought bravely, surrounded by a superior Persian cavalry. Mazey broke through to the lines of the Macedonians with his cavalry, then a bloody battle ensued in isolation from the rest of the army. The Persians plundered the rear, and in order to repel them, Macedonians had to send part of the main army.
Alexander decided to make a tactical maneuver on the right flank (one of the greatest moves in military history). Alexander made this maneuver and managed to bypass the terrain where Persians had put iron spikes in the ground, to try to prevent a cavalry charge. It is not known in which formation he led his troops in this moment. Persians tried to attack Alexander from the right. They sent their infantry to attack the Macedonian cavalry with long spears.
The Persian cavalry was engaged in the battle with the 2nd line of the Macedonian army. As a result of Alexander’s maneuver, a gap had appeared in the front line of the Persian army; Alexander then attacked that gap in the line with all his might. The attack was aimed to kill the Persian Emperor Darius.
In the midst of battle, the driver of Darius’ chariot was killed by a dart; but the Persians mistook his death as the death of the Persian Emperor. Panic swept over the ranks of the Persian soldiers near the event. The left flank of the Persian army started to fall apart and retreat. Seeing this, Darius had no choice but to flee; after which his troops, who were nearby, fled also. Due to a cloud of dust and the large area of battle, the Persians of the right wing did not see the flight of their king; and continued to press Parmenion who was in great danger of being killed himself. Alexander had to turn his cavalry and attack the Persian army to ease his commander’s situation. Soon, after learning about Darius flight, Mazey left the battlefield, and Alexander tried to catch the Persian Emperor, but it was too late.
Results of the battle
Alexander’s elite cavalry lost almost 100 men, and the rest of cavalry was cut in half. The infantry lost around 2,000 men but those are only estimates. The Persians lost 30,000 men, and even more were taken prisoner by the Macedonians.
After the Battle of Gaugamela, most of the cities of the old Persian Empire surrendered to Alexander, with Persian nobility swearing their allegiance to Alexander, the new ruler of Asia. The Persian King Darius III fled to the east in the hope of building an army there; but was captured and then killed by his own men. After this, the Persian Empire ceased to exist. This battle had become a legendary victory that demonstrates a smaller army with a better chain of command can outmaneuver and destroy a larger enemy.