The Battle of the Granicus River: Alexander the Great’s First Major Success Against the Persians
The Battle of the Granicus River, fought in May 334 BC, was the first major victory of Alexander the Great against the Persian Empire. The battle set the stage for Alexander the Great‘s conquest of Asia Minor (modern-day Turkey) and paved the way for his later victories over the Persian Empire.

Alexander the Great
Alexander III of Macedon, known as Alexander the Great, began his campaign against the Persian Empire by crossing the Hellespont, a narrow strait that separates Europe from Asia, with a large army in 334 BC. The Persian satraps (governors) of Asia Minor assembled a significant force to counter the Macedonian threat.
The Battle

“The Battle of the Granicus” (1665) by French painter Charles Le Brun
The Persian army decided to confront Alexander and his troops near the Granicus River in northwestern Asia Minor. The Persians took a defensive position on the high bank of the river.
The Persian army’s frontline was made up mainly of cavalry, with their infantry (mainly Greek mercenaries) held as a second line at the rear. Alexander’s forces were composed of both heavy infantry (phalanx) and elite Companion cavalry, among other units.
Despite the challenging position and the fast-flowing river, Alexander launched an attack. He led his Companion cavalry on the right flank, charging the Persian left. The initial assault faced stiff resistance, but Alexander’s tactics, audacity, and the competence of the Macedonian phalanx eventually broke the Persian lines.
Aftermath of the Battle
The Persians suffered heavy casualties, especially among their nobles and satraps. The Greek mercenaries fighting for Persia, who were not part of the initial fighting at the river, were later surrounded by Alexander.
Instead of showing them leniency, Alexander, wanting to send a message to other Greeks who might consider fighting against him, treated them as traitors. Many were killed, and others were sent to do hard labor in Macedonia.
The victory at the Granicus opened up Asia Minor to Alexander. City after city surrendered to him, and he methodically took control of the region.
The Battle of the Granicus River showcased Macedonian ruler’s tactical brilliance and set the tone for the subsequent battles against the Persians, ultimately leading to the downfall of the Persian Empire, which was a major superpower of the ancient world.
Questions & Answers

“Alexander the Great in the battle against the Persians at the Granicus”. Painting by Dutch painter Cornelis Troost, 1737.
How old was Alexander the Great at the Battle of the Granicus?
During the Battle of the Granicus, Alexander was only 22 years old but had significant military experience.
Under his father Philip II‘s rule, who had sought to conquer Greek cities that were in the orbit of the Persian Empire, a young 16-year-old Alexander led the cavalry. He was present when Philip expressed intentions to confront the Persians, whose Achaemenid dynasty was a threat to the Greeks from across the Aegean for more than a century.
What were some of the major events leading up to the Battle of the Granicus?
Before putting his plan to conquer the Persian Empire into action, the boy-king Alexander first needed to secure his European territories.
As he ascended to the throne in 336 BC, many perceived a potential vulnerability in the young king, leading to uprisings in the Balkans. He knew he had to be ruthless in quelling those revolts.
Take the case of Thebes, an ancient Greek city; it’s said that Alexander completely leveled the city before distributing its wealth and territories among neighboring cities.
This act and many others signaled Alexander’s unwavering determination and ambition. It suggested he was even more relentless than his father.

While Alexander’s army mainly comprised Macedonian and allied Greek forces, the Persian forces were a mix of Greek mercenaries and Persian levies. Image: A Roman copy of an original 3rd century BC Greek bust depicting Alexander the Great, Ny Carlsberg Glyptotek, Copenhagen
What was the size of Alexander’s forces at the battle?
According to ancient accounts, Alexander led between than 20,000 and 36,000 soldiers to the Granicus. His forces included Macedonians and Greeks.
What was the size of the Persian opposition?
Alexander’s forces faced off against armies of Persian satrapies, which included Greek auxiliaries and hoplite mercenaries. All in all, the Persians had more than 15,000 men. In some account, it’s said that the Persians had close to 40,000 men.
Like the Macedonians, they were confident that their phalanxes would prove invaluable in the battle.
Who were some of the military leaders at the Battle of the Granicus?
On Alexander’s Side (Macedonians and Greeks):
- Alexander the Great: The young king of Macedon led the charge and played a pivotal role during the battle.
- Parmenion: Alexander’s most experienced general, Parmenion commanded the left wing of Alexander’s army. He was also Alexander’s second-in-command.
- Philotas: Son of Parmenion, he played a significant role in the cavalry.
- Cleitus the Black: He notably saved Alexander’s life during the battle, warding off a Persian noble who was about to strike Alexander down.
On the Persian Side:
- Memnon of Rhodes: A Greek mercenary in Persian service. He had suggested avoiding a direct confrontation with Alexander but was overruled by the local satraps.
- Arsites: The Persian satrap of Hellespontine Phrygia.
- Spithridates: A Persian nobleman and satrap who attempted to strike down Alexander during the battle but was thwarted by Cleitus the Black.
- Rheomithres, Petenes, and Niphates: Other satraps and commanders present in the Persian army.

Memnon of Rhodes (c. 380 – 333 BC) was a leading Rhodian Greek commander in the service of the Persian Achaemenid rulers, especially Darius III (reign: 336–330 BC). Image: Coinage of Memnon of Rhodes, Mysia. Mid 4th century BC
Why did the Persian commanders not heed the advice of Memnon of Rhodes?
Before the battle, Memnon of Rhodes, serving as a Greek mercenary leader for the Persians, counseled the Persian satraps and commanders in Asia Minor to avoid direct confrontation with Alexander’s forces.
Memnon recommended a sort of scorched-earth approach, suggesting they devastate their lands to starve Alexander’s already dwindling supplies.
While strategically sound, the satraps refused to heed the advice of Memnon. They were reluctant to ruin the territories they were entrusted with by the Persian King of Kings. Besides, those satraps yearned for the fame of a direct battle with the Macedonians.
Consequently, they disregarded Memnon’s advice, choosing to face Alexander in open combat, a decision that greatly went in the favor of the young Macedonian conqueror.
What was Alexander the Great’s Companion Cavalry?
The Battle of the Granicus began when personally led his Companion Cavalry across the river.
Alexander the Great’s Companion Cavalry (in Greek: “Ἑταῖροι” or “Hetairoi”) was the elite cavalry unit of the Macedonian army and played a crucial role in Alexander’s conquests. Top of Form
The Companions were considered the most prestigious military unit in Alexander’s army. Their members often came from the Macedonian nobility, making them a distinct and elite group among the Macedonian forces
The Companion Cavalry was primarily a shock troop, meant to deliver decisive charges against enemy lines. They were instrumental in many of Alexander’s major battles, often turning the tide of battle in his favor.
Given their noble status, many of the Companions had personal ties to Alexander. They were not just his elite military unit but also his close friends and confidants. This closeness to the king meant that they also played significant roles in the political and administrative aspects of Alexander’s empire.
Who saved Alexander the Great’s life at the Granicus?
The battle between Alexander the Great and the Persian forces at the Granicus River was fierce and presented moments of life-threatening danger for Alexander.
In the heat of the battle, two Persian commanders, Rhoesaces and Spithridates, identified an opportunity to strike down Alexander.
Rhoesaces managed to get close enough to Macedonian king to deliver a blow with his scimitar. The force of this strike was primarily absorbed by Alexander’s helmet, showcasing the vital role played by armor in ancient warfare.

Spithridates, the Persian satrap of Ionia and Lydia, attacks Alexander from behind. Detail from Charles le Brun’s 1665 painting “Battle of the Granicus”.
Alexander’s training, reflexes, and combat skills were then immediately evident when he retaliated swiftly, driving his lance directly into Rhoesaces, eliminating the immediate threat.
However, even as he was countering Rhoesaces, another danger lurked right behind him. Spithridates saw an opening to deal a potentially fatal blow to the Macedonian king.
But, Alexander was not alone in the fray. Cleitus ‘the Black’ was one of his trusted commanders and was closely monitoring the unfolding situation.
Recognizing the imminent danger to Alexander from Spithridates, Cleitus reacted without hesitation. In a decisive and protective move, he cut off Spithridates’ raised arm, thereby saving Alexander from a possible fatal blow.
What did Alexander do after the battle?
Emerging triumphant from this encounter, the casualties on Alexander’s side were comparatively minimal, with a little more than a hundred losses, according to some ancient accounts.
In contrast, the Persians suffered heavy losses, with over a thousand of their cavalry killed, including several of their key leaders.
However, the aftermath of the battle also sheds light on Alexander’s uncompromising approach towards perceived betrayal. Greek mercenaries, who had chosen to serve under the Persian flag, were viewed by Alexander as traitors to their Hellenic roots.
Instead of showing leniency or attempting to win them over, he made the stark decision to annihilate them entirely, reinforcing his relentless determination and sending a clear message about the consequences of opposing him.
What was the importance of the Battle of the Granicus?
With their field army defeated, Persian forces in the region were compelled to adopt a more defensive stance. The cities still under Persian control in the vicinity became critical strongholds.
Instead of being able to confront Alexander in open battle, they had to fortify their cities and prepare for sieges. This shift in tactics reflects the change in the balance of power post-Granicus: from an aggressive Persian presence to one that was attempting to resist and weather the storm of Alexander’s advancing forces.
In summary, the decisive victory at Granicus signaled the commencement of Alexander’s ambitious endeavor to conquer the vast Persian Empire, setting the stage for subsequent confrontations and the eventual spread of Hellenistic culture across the region.
READ MORE: Achaemenid Rulers and the Length of Reign