Battle of Gaugamela (331 BCE): Alexander’s Achaemenid Armageddon

Following his defeat at the hands of Alexander at the battle of Issus in 333 BCE, Darius III withdrew to Babylon. Here he worked to rebuild his army and gather his forces from across the empire.

Rather than marching straight to Babylon, Alexander moved to subdue Egypt and the Levant. He did so to protect his rear and to remove the threat of the Achaemenid navy. The ships were useless without their ports. In the meantime, Darius also attempted to negotiate a settlement with Alexander. In exchange for agreeing to a peace treaty Alexander would receive half of the Achaemenid Empire, a vast sum of money, and Darius’ daughter in marriage. Alexander refused and the Battle of Gaugamela followed.

Having secured Egypt, Alexander marched northwards toward the Tigris and Euphrates rivers. Darius III dispatched a force of around 3,000 cavalry to block Alexander from crossing the Euphrates, but they instead fled when the Macedonians approached. Alexander followed a northern route so that his left flank was protected by the Euphrates and the mountains of Armenia. While this was not the most direct route to Babylon, it made it easier for his army to forage for supplies.

Crossing the Tigris proved far more difficult due to the deepness of the river. On the other side, the Macedonians began to suffer from Achaemenid scorched-earth tactics and the increasing levels of heat. Captured Achaemenid scouts eventually revealed that Darius and his army were encamped at a place called Gaugamela. At this point, the armies were a mere eight miles away from each other.

The Achaemenids appear to have been caught off guard by Alexander’s choice to follow the northern route. They failed to either harass Alexander’s army or cut off its very long and vulnerable supply lines. It has been argued that Darius III was expecting Alexander to follow the shorter, southern route. This was the route that Cyrus the Younger had taken with his Greek mercenaries in 401 BCE. Others have argued that Darius III essentially led the Macedonians to Gaugamela, which was where he preferred to give battle.

Gaugamela—which means “the camel’s house or hump,” named after the large mound or hill that dominated the area—was a large flat plain. Here Darius III would be able to bring his superior numbers to bear without having to worry about the terrain.

The army that Darius III gathered for the battle of Gaugamela was truly enormous. While Alexander was dealing with Egypt and the Levant, Darius drew troops from across the empire. Modern estimates based on the ancient texts range from 52,000 to over 200,000. According to the sources there were 40,000-200,000 Achaemenid infantry, 10,000 Persian Immortals, 8,000-10,000 Greek mercenaries, 1,500 archers, 12,000-45,000 Achaemenid cavalry, 1,000-2,000 Bactrian cavalry, 200 scythed chariots, and 15 war elephants. However, despite their numbers, Darius troops were by and large of a lower quality than their Macedonian enemies. Additionally, since the army was assembled from across the empire there were serious language barriers which made communication difficult.

Alexander’s army was much smaller. His forces consisted of his own Macedonians, Greeks of the Hellenic League, additional Greek mercenaries, and levies from his Paeonian and Thracian vassals. The Macedonian army numbered between 30,000 and 50,000 soldiers. Our best estimate of Alexander’s forces comes from the ancient historian Arrian. According to Arrian, Alexander had a force of 31,000 heavy infantry, 9,000 light infantry and archers, and some 7,000 cavalry. Although this was a significantly smaller force, the soldiers were all experienced veterans with several hard campaigns under their belts.

Preparations and Deployment

Following their arrival in the vicinity of Gaugamela, Alexander realized that the Achaemenids intended to fight. He therefore erected a fortified encampment and allowed his men to rest for four days before marching out to give battle. The Achaemenids were not idle during this time, they continued their efforts to level the battlefield and eliminate any obstacles that might hinder their actions.

On the day of the battle the Achaemenids were deployed and waiting for the Macedonians. The Achaemenids were deployed in essentially two lines. Darius III took up his position in the center of the first line with his elite infantry and cavalry. The rest of the cavalry was divided between the left and right wing of the first line, along with the Persian scythed chariots. The second line consisted of the rest of the Achaemenid infantry, which was of lower quality. For whatever reason, the war elephants appear to have remained in the Achaemenid camp on the day of the battle.

The Macedonian army was essentially divided in two, with Alexander commanding the right, and old General Parmenion commanding the left. Alexander placed his heavy infantry form in two lines, with his Macedonians in the front and a reserve of Greek mercenaries. Since the Achaemenid army was so much larger and had a longer line, the reserve was necessary to prevent the Macedonians from being outflanked.

Alexander took up position on the right with his Companion cavalry and the lighter Greek and Paeonian cavalry. Parmenion was similarly positioned on the left with the Thessalian and Thracian cavalry. The light infantry was divided between the two wings to help support the cavalry and form a link with the heavy infantry in the phalanx.

Alexander initiated the battle by ordering his phalanx to advance in echelon to attack the Achaemenid infantry deployed around Darius. An echelon attack is when each unit advances in succession rather than at the same time. In this instance, the purpose was to lure the Achaemenid cavalry into attacking the perceived gaps in the Macedonian line. With the infantry now engaged, Darius III ordered a massive attack consisting of cavalry and infantry on the opposite end of the Macedonian line where Parmenion was in command.

Meanwhile, Alexander began to ride with his Companion cavalry to the extreme end of his right flank and possibly even beyond. His plan was to draw off a large portion of the Achaemenid cavalry which would ride after him. This would in turn create a gap in the Achaemenid line that Alexander could exploit. When the gap opened, Alexander and his Companion cavalry would turn to attack the gap, threatening Darius’ position, while the rest of the Macedonian cavalry held off their Achaemenid counterparts. Following his defeat at Issus, Darius appears to have hoped to fight a more defensive battle. However, when he realized what was happening, he launched an attack of his own.

Cavalry and Chariots

The Achaemenid cavalry from the left wing rode to attack the Macedonian cavalry on the extreme right of the Macedonian army. Though greatly outnumbered by the Achaemenids, the Macedonians fought on and stoutly resisted. By carefully feeding in reserves and launching repeated charges they were able to prevent the Achaemenid cavalry from getting around the flank of the Macedonian army. The fight was long and hard in this sector, and only turned in favor of the Macedonians when the last of the cavalry reserves were sent in. By now, Alexander had effectively won the battle. However, on the Macedonian left flank, the fighting favored the Achaemenid cavalry. Slowly, they encircled the Macedonians, threatening to destroy them.

It was at this point that Darius launched his scythed chariots at the troops under Alexander’s command. Though often derided, scythed chariots could be deadly in the right circumstances. In this instance, however, most of the Achaemenid chariots were intercepted by Alexander’s light infantry, who killed and disabled many with their javelins. Those who made it through charged the Macedonian lines. The Macedonian infantry responded by opening their ranks, allowing the chariots to pass through harmlessly. The few chariots that made it through were then dispatched by the Macedonian reserves and those guarding the camp.

The movement of the Achaemenid cavalry working its way around both flanks of the Macedonian army gradually drew it away from the infantry. This was further exacerbated by the Macedonian infantry, which, advancing in echelon, engaged the infantry at the center of the Achaemenid army. As a result, a dangerous gap opened up on the left flank of the Achaemenid line. It was this moment that Alexander had been waiting for. Slowly, he brought up his reserves and withdrew his Companion cavalry from the fighting. Alexander then arranged his troops in a giant wedge and prepared to attack.

The Macedonian wedge charged straight through the gap in the Achaemenid line, with Alexander in the lead. Since the infantry of the Achaemenid center was still engaged with the Macedonian phalanx, there was little they could do to hinder the attack. The Macedonian charge slammed into Darius’ royal guard and Greek mercenaries went scattering before them.

The fighting was short, but fierce. Realizing that he was in danger of being cut off, Darius turned and fled. While many have criticized this decision, had Darius been killed or captured, the Achaemenid resistance would have collapsed. Even now, the Achaemenid Empire still had vast resources to draw on. Yet when Darius fled the rest of his army soon followed. Alexander was poised to vigorously pursue Darius, but it was at this point that he received a disturbing message from Parmenion who was commanding the Macedonian left wing.

Achaemenid Armageddon

While Alexander’s tight wing was driving Darius from the battlefield, the rest of his army was in mortal danger. The Macedonian infantry was hard-pressed and had not been able to follow after Alexander when he charged after Darius. Meanwhile, the Achaemenid cavalry was fighting very well against the troops under Parmenion, pushing them back and encircling them. This now created a gap in the Macedonian line between the phalanx and the cavalry, and the light troops of the Macedonian left. This gap was exploited by the Achaemenid cavalry of the center, who broke through the Macedonian lines. Rather than attacking the phalanx or Parmenion’s troops from the rear, these troops attacked the Macedonian camp, which they began to loot.

Alexander thus faced an existential threat to the very survival of his army. He, therefore, broke off his pursuit of Darius and rode to the rescue of his men. According to ancient sources, the cavalry fight that followed Alexander’s ride to Parmenion’s aid was the fiercest of the battle. At the same time, the Macedonian infantry reserve marched to drive the Achaemenids from their camp.

The Achaemenid cavalry had dispersed to loot the Macedonian camp and search for Sisygambis, the Queen Mother who had been captured following the Battle of Issus. While they located Sisygambis, she refused to escape with them and the dispersed Achaemenid cavalry was no match for the Macedonian reserves. With the situation now firmly in the Macedonians’ favor the Achaemenids were in full retreat. Parmenion secured the Achaemenid camp and baggage, while Alexander resumed his pursuit of Darius.

The Battle of Gaugamela was one of Alexander’s finest battles. Afterward, the loot gathered by Parmenion included 4,000 talents, Darius’ personal bow, and nearly a dozen war elephants. Alexander now controlled half of the Achaemenid Empire. The only disappointment for the Macedonians was the failure to capture Darius.

When Alexander rode to the rescue of the rest of his army, Darius made good his escape and crossed the mountains to the safety of Ecbatana. Since he was unable to immediately continue his pursuit of Darius, Alexander instead marched on the great city of Babylon, which he occupied.

For the Achaemenids, Gaugamela was an absolute disaster. Vast resources had been gathered to oppose Alexander’s advance but to no avail. Instead, the entire Western half of the empire had been lost to the invading Macedonians. The army was in tatters and thoroughly demoralized following its continuous defeats at the hands of the Macedonians.

Darius still intended to continue the fight, but his credibility had been all but lost. For a second time, he had been forced to flee from the battlefield by a numerically inferior foe. Though Darius was the legitimate king the loyalty of his remaining satraps was wavering. Led by Bessus, the satrap of Sogdia, the Achaemenid nobility began to plot Darius’ downfall.