How Alexander the Great Won the Battle of the Granicus

With Greece and the Balkans secure, Alexander the Great led his army across the Hellespont into Asia Minor. A revolt in Egypt had drawn away the new Achaemenid king, Darius III, and his army. However, the local Achaemenid satraps were not about to let Alexander do as he pleased. The satraps of Asia Minor had plenty of experience fighting Greeks and had driven back an earlier Macedonian expedition launched by Alexander’s father, Philip II. Now, the satraps marched to confront Alexander on the banks of the Granicus River in 334 BCE.

Having secured control of the Greek city-states, in 336 BCE Philip II of Macedon dispatched an advance guard across the Hellespont into Asia Minor. This force was led by Parmenion, Philip’s best general, and was tasked with establishing a base of operations so that the rest of the army could cross over later. Most of the Greek cities of Asia Minor went over to the Macedonians. At the same time, a massive revolt broke out in Egypt. The situation soon turned against the Macedonians when word arrived that Philip had been murdered.

Philip’s son, Alexander, rose to take control of the Macedonian throne. However, the Greek city-states and Thracian tribes to the north revolted, threatening Alexander’s power. This meant that for the time being, the Macedonian expeditionary force in Asia Minor was on its own. Darius III suppressed the Egyptian revolt in 335 BCE and dispatched an army of Greek mercenaries led by Memnon of Rhodes to deal with the Macedonians. In short order, they dealt the Macedonians two defeats. By the end of 335 BCE, the Macedonians retained control of only a small area. However, they had held on, and in early 334 BCE, Alexander was able to cross over the Hellespont with the main Macedonian army.

Clash of Empires: Alexander’s Army vs. Persia’s Forces

Opposing the Macedonians were the forces of the Achaemenid satraps of Asia Minor. Information about the size and composition of the Achaemenid army is inconsistent or unavailable. The army was primarily drawn from the troops available to the satraps, along with some soldiers of the regular Achaemenid army, and a large contingent of Greek mercenaries. Estimates place the Achaemenid infantry at about 20,000, with 4,000–5,000 of these being the Greek mercenaries and the rest local levies. The Achaemenid cavalry was of higher quality than the infantry and is estimated at around 5,000–10,000. Most modern historians, therefore, have the Achaemenid army at 25,000 to 30,000, though some estimates have been much lower.

There are three main accounts of the battle of the Granicus that have come down to us from antiquity by the historians Arrian, Plutarch, and Diodorus Siculus. The major point of contention is whether the battle was fought after Alexander’s army crossed the river and deployed on the other side, as in Diodorus’ account, or if the armies deployed and fought with the river between them, as with Arrian and Plutarch’s accounts. Both versions have the commanders making inexplicable decisions in their deployments and subsequent actions. Therefore, we will follow the accounts of Arrian and Plutarch, suggesting that the Achaemenids may not have intended to fight a battle at that juncture. Their questionable deployment may have been intended as a show of force, assuming Alexander would not attempt a contested river crossing.

As the armies approached, they deployed on opposite banks of the Granicus River. The Achaemenids deployed with their cavalry atop the steep bank of the river, likely to intimidate the Macedonians. While some of the infantry may have been present, the majority, including the elite Greek mercenaries, were deployed behind the cavalry—apparently too far back to adequately support the Achaemenid cavalry. On the other side of the river, Alexander deployed with his Companion cavalry, Paeonian cavalry, and prodromoi on his right, along with the archers and Agrianians. His left consisted of the Thracian cavalry, as well as the allied Greek cavalry and Thessalian cavalry. The center was made up of the pike-wielding Foot Companions of the phalanx, with the elite hypaspists in the place of honor on the right.

The commander of the Achaemenid forces at the Granicus was the satrap Arsites, who shared command with several other satraps and members of Darius III’s family. However, the most influential figure in the Achaemenid army at the time of the battle was the Greek mercenary commander Memnon of Rhodes. Memnon (ca. 380–333 BCE) entered the service of the satrap of Phrygia in 358 BCE and participated in a failed revolt against the Persian king. Following the revolt, Memnon fled to Pella, the capital of Macedonia. There, Memnon became acquainted with both Philip II of Macedon and his son, Alexander. According to Plutarch, Memnon and Alexander had lengthy discussions of military matters. Both came away with an understanding of the other side’s military capabilities, political strengths, and weaknesses.

In 343 BCE, Memnon was able to reenter Achaemenid service and soon found himself facing off against Philip and the Macedonians. At Byzantium in 339 BCE, Memnon helped to defend the city from Philip’s assaults before being recalled to deal with the Macedonian expedition of Parmenion in Asia Minor. With the arrival of Alexander and the Macedonian army, Memnon advocated a scorched earth policy. He knew that the Greeks were unhappy with Macedonian rule and that Alexander’s army would have difficulty maintaining its supplies.

However, Memnon’s counsel was overruled by the satraps, who did not want to damage their lands. At Granicus, Memnon appears to have been with the cavalry rather than his Greek mercenaries. While this may have been because the satraps distrusted him, a more likely explanation is that Memnon intended a show of force to intimidate the Macedonians and had not expected to fight at this point.

The battle began with Alexander launching a cavalry attack across the river at the Achaemenid left flank. The attack consisted of a squadron of the Companion cavalry, the Paeonian cavalry, and prodromoi, along with an unspecified unit of infantry. From their position atop the riverbank, the Achaemenid cavalry rained missile fire down on the attacking Macedonians, blunting their attack. Outnumbered and suffering casualties, the Macedonians pulled back. Sensing an opportunity, the Achaemenid cavalry left the height of the riverbank to pursue the Macedonians into the river.

Modern historians have argued that the Macedonian retreat was a ruse. It was intended to lure the Achaemenid cavalry down from their position on the riverbank and disrupt their formation. Whether intentional or not, the Achaemenid cavalry was now vulnerable. Alexander launched an attack with the rest of his Companion cavalry and the entire right wing of the infantry phalanx. With the Achaemenid cavalry formation disrupted, Alexander was able to lead his own cavalry across the river and ascend the riverbank. Such an attack would have required skillful maneuvering on Alexander’s part, as his cavalrymen would have been vulnerable until they deployed on the opposite side of the river. This has led to a great deal of debate amongst modern scholars. Having reached the opposite side of the river, Alexander charged directly at the massed Achaemenid cavalry.

Clash of Champions: Alexander’s Personal Battles at Granicus

Having crossed the river, the Macedonian cavalry, led by Alexander, closed in on their Achaemenid opponents. The Macedonians now held the advantage. Their longer lances were far more deadly at close range than the shorter Achaemenid javelins. It has also been suggested that Alexander’s cavalry may have charged the Achaemenids in a wedge or diamond formation. This would have enabled them to penetrate deep into the Achaemenid formation, disrupting it. Alexander, as was his usual practice, was leading his cavalry from the front, actively participating in the battle and exposing himself to danger.

Cavalry battles were fluid, swirling affairs, as it was imperative for riders to remain mobile since standing still negates all the advantages of the cavalryman. According to Arrian and Plutarch, Alexander engaged in a series of duels in the finest Homeric tradition. During the fighting, Alexander came face-to-face with Mithradates, Darius III’s son-in-law and one of the Achaemenid cavalry commanders. Charging straight for him, Alexander killed Mithradates by thrusting his lance into his face. This exposed Alexander to an attack from the Achaemenid noble Rhosaces, who swung his sword at Alexander’s head.

Rhosaces’ blow connected, though his helmet saved him. Alexander killed Rhosaces with a thrust of his lance into the chest, but was then attacked by Spithridates, the satrap of Ionia and Lydia. Before Spithridates could strike Alexander from behind, he was killed by the Macedonian commander Cleitus the Black. By now, the Macedonian cavalry had established itself on the riverbank and was driving the Achaemenids back.

The left flank of the Achaemenid cavalry broke and fled, with the center following shortly thereafter. According to the sources, there appears to have been some fighting between the Achaemenid and Macedonian infantry. However, exactly which units were involved and the extent of the fighting were not recorded. With the flight of the Achaemenid cavalry and whatever other infantry may have been engaged, Alexander turned his attention to the Greek mercenaries serving under Memnon. Up to this point, they had taken no part in the battle despite being the best infantry the Achaemenids had. Unfortunately, they were deployed too far back from the cavalry to provide support. Additionally, their commander, Memnon, was forward with the cavalry when the battle began and was unable to issue orders.

The Greek mercenaries still represented a dangerous force, so Alexander directed his attacks towards them. With the rest of the Achaemenid army in flight, the mercenaries retreated to a more defensible position on a rise. They then attempted to negotiate their surrender with Alexander, who refused. The Macedonian Foot Companions attacked the mercenaries from the front, while the cavalry circled to attack from the flanks and the rear. The Greek mercenaries fought back bitterly. Eventually, they were defeated, and few managed to escape the battlefield. Most of the Macedonian casualties occurred during the fight with the mercenaries.

Granicus’s Legacy: A Gate Opened for Alexander the Great’s Empire

Determining casualties in ancient battles is notoriously difficult. Based on the source material, it is estimated that between 100–120 Macedonians were killed, mostly among the cavalry. Achaemenid casualties are even more difficult to estimate, but modern historians place them around 5,000–6,000. Additionally, around 2,000 Greek mercenaries were captured. Alexander viewed them as having betrayed their fellow Greeks, so they were sent to Macedon to work as slaves. He also sent a votive offering of 300 suits of armor to the temple of Athena in Athens.

Following the battle, the Achaemenids withdrew their garrisons from several cities across the region, which went over to Alexander. The Macedonians now occupied Dascylium, Magnesia, Tralles, Ephesus, and most importantly, Sardis. Only Miletus resisted and was besieged. The western half of Asia Minor had effectively fallen. However, the Achaemenid army had not suffered disastrous losses and was able to regroup at Halicarnassus. Resistance was still possible as the Achaemenids had unimaginable resources at their disposal. Yet the strategic situation was precarious. Alexander’s Macedonians had established a base of operations and could march inland at any moment. The stage had been set for the conquest of the Achaemenid Empire.