The Ancients

The Invasion of Persia | Alexander the Great

February 12, 2026

Key Takeaways Copied to clipboard!

  • Alexander the Great's invasion of the Persian Empire began in spring 334 BC with a symbolic crossing of the Hellespont, driven by ambition to surpass his father, Philip II. 
  • The Macedonian army, though smaller than the Persian forces, possessed superior tactical cohesion, demonstrated by its success at the Battle of the Granicus against local satraps and Greek mercenaries. 
  • Alexander's early campaign strategy involved securing the Mediterranean coastline by taking key cities and ports, while simultaneously using dramatic acts like cutting the Gordian Knot to cement his image as a divinely favored conqueror. 
  • Alexander's victory at the battle discussed (late 333 BC) was a major blow to Persian infantry, particularly the Greek mercenaries and Persian troops equipped in the Greek style, marking a shift in future Persian military focus towards cavalry. 
  • Alexander's treatment of Darius's captured royal family following the battle—showing respect and dignity—became a significant historical moment emulated by later commanders like Scipio Africanus and contributed to the chivalric image of Alexander. 
  • Despite defeating Darius, the King of Kings, in battle within two years of crossing the Hellespont, Alexander still faced the challenge of conquering the vast majority of the Persian Empire, which retained significant manpower and resources. 

Segments

Crossing into Asia
Copied to clipboard!
(00:00:44)
  • Key Takeaway: Alexander’s invasion force crossed the Hellespont in spring 334 BC, carrying soldiers and supplies for the conquest campaign.
  • Summary: The invasion began in spring 334 BC with a crossing over the Hellespont (modern Dardanelles) into Asia. The ships were filled with soldiers, horses, and vital supplies for the campaign ahead. Alexander, dressed in royal armor, stood at the prow, focused on the Asian coastline.
Alexander’s Ambition and Troy
Copied to clipboard!
(00:02:54)
  • Key Takeaway: Alexander made a symbolic landing near Troy, viewing himself as following the heroic ancestor Achilles in his conquest of the Persian superpower.
  • Summary: Alexander landed separately from the main force near the fabled city of Troy, fulfilling a personal dream linked to Homeric heroes. He launched an iron-tipped spear into the beach, symbolically claiming the Persian Empire as his territory. This act signaled a campaign of conquest, not a mere raid.
Episode Context and Army Size
Copied to clipboard!
(00:04:51)
  • Key Takeaway: This episode focuses on the early challenges of the invasion and the confrontation with Darius III, with the initial invasion force estimated around 40,000 troops.
  • Summary: This is the second episode in the series, focusing on the invasion following Alexander’s consolidation of power. The army size is estimated between 30,000 and 50,000, composed of Macedonians, allied Greeks, and specialized contingents like the Pike Phalanx and cavalry.
Persian Strategy and Satrapal Response
Copied to clipboard!
(00:17:35)
  • Key Takeaway: The Persian King of Kings, Darius III, did not immediately engage, expecting local satraps to crush the invasion, a common pattern for handling peripheral threats.
  • Summary: The Persian Empire’s vast size meant rapid mobilization was impossible, so local satraps were tasked with dealing with Alexander initially. Persian governance often involved committees of satraps, which hindered quick, unified military decisions. The local forces included significant cavalry (10-20,000) and Greek mercenaries opposing Alexander.
Granicus Battle Details
Copied to clipboard!
(00:25:02)
  • Key Takeaway: At the Battle of the Granicus, Alexander ignored Parmenion’s caution and launched a direct charge, focusing the narrative on his personal combat where he was nearly killed.
  • Summary: The Persians deployed cavalry statically on the riverbank, a tactical error against Alexander’s charging horsemen. Alexander targeted the enemy leadership, leading the Companion Cavalry, and was saved from a fatal blow by Cleitus the Black. The battle concluded with the dispersal of the Persian army and the massacre of thousands of unformed Greek mercenaries.
Post-Granicus Campaigning
Copied to clipboard!
(00:38:27)
  • Key Takeaway: Following Granicus, Alexander systematically moved down the Aegean coast, prioritizing the capture of coastal cities to deny bases to the superior Persian fleet.
  • Summary: Alexander avoided the warlike highland tribes, focusing instead on major administrative centers like Sardis and Ephesus, where he offered to rebuild the Temple of Artemis. The Macedonian army’s siege capacity, inherited from Philip, allowed them to take fortified cities like Halicarnassus quickly, unlike previous Greek expeditions.
Gordium and the Knot
Copied to clipboard!
(00:45:17)
  • Key Takeaway: Alexander’s visit to Gordium, where he cut the Gordian Knot, was a calculated act of political theater amplified by his accompanying historians to assert his destiny to rule Asia.
  • Summary: The story of the Gordian Knot, involving a complex knot on a wagon tied to a prophecy of ruling Asia, was heavily promoted by Alexander’s press corps. He either cleverly untied it or slashed it with his sword, reinforcing his image as a decisive leader favored by the gods. This boasting, however, later led some Roman emperors to criticize his excessive self-promotion.
The Road to Issus
Copied to clipboard!
(00:53:08)
  • Key Takeaway: The Battle of Issus occurred largely by accident when Darius III, unable to wait indefinitely due to supply issues, moved his massive army behind Alexander’s position in Cilicia.
  • Summary: Alexander fell ill in Cilicia, delaying his advance while Darius mobilized his main force. Darius, needing to move his large army to avoid sickness and maintain momentum, inadvertently positioned himself behind Alexander near the River Issus. Alexander turned back to confront Darius on this narrow terrain.
Battle of Issus Outcome
Copied to clipboard!
(00:56:54)
  • Key Takeaway: At Issus, Alexander’s superior close-order fighting and leadership, particularly by the Paspids and Companion Cavalry, broke the Persian lines, resulting in Darius fleeing and the collapse of the Persian infantry formations.
  • Summary: Darius commanded a larger army, including more Greek mercenaries and Persian troops trained in close combat, but the Macedonians proved superior in the ensuing melee. Alexander led the decisive charge, aiming for the enemy leadership, causing Darius to flee the field. This battle marked the last time large numbers of Greek mercenary infantry would feature prominently against Alexander.
Macedonian Close Combat Superiority
Copied to clipboard!
(00:58:56)
  • Key Takeaway: Macedonian forces, particularly the elite Hypaspists, excelled in close-in fighting, leading to the collapse of the Persian army formation.
  • Summary: The Hypaspists, serving as elite footguards between the phalanx and cavalry, were superior in close-in fighting when Macedonian formations occasionally broke up. Alexander personally led these troops, contributing to the eventual rout of the Persian army. Darius fled the field, allowing Alexander to claim a moral victory despite failing to capture the Persian King of Kings.
Immediate Aftermath and Victory Context
Copied to clipboard!
(01:00:06)
  • Key Takeaway: The victory in late 333 BC, less than two years after crossing the Hellespont, was significant but left Darius in control of most of his empire’s resources.
  • Summary: This decisive battle occurred less than two years after Alexander crossed the Hellespont, following earlier victories and sieges. Although Alexander defeated the ‘King of Kings,’ Darius retained most of his empire, wealth, and manpower, meaning Alexander could not afford a single loss moving forward. Darius, unlike Alexander, could cope with a single defeat at this stage.
Pompeii Mosaic Depiction
Copied to clipboard!
(01:01:05)
  • Key Takeaway: The flight of Darius at Issus is immortalized in the House of the Fawn floor mosaic in Pompeii, offering a key visual representation of the event.
  • Summary: The floor mosaic depicts Alexander on the left with his companions, contrasting with Darius and his charioteer fleeing in panic, causing chaos in his own ranks. This Roman-era mosaic is a crucial colored representation of Alexander, influencing theories about his physical appearance, such as his hair color. The mosaic’s proportions were designed for viewing on a floor rather than as a modern painting.
Capture and Treatment of Royal Family
Copied to clipboard!
(01:02:28)
  • Key Takeaway: Alexander captured Darius’s sister, wife, and mother, treating them with profound respect, which became a model for honorable conduct in warfare.
  • Summary: When Darius fled, he left behind his baggage train, which included the women of the royal household, as the heart of the empire followed the King on campaign. Alexander refused to abuse or execute them, instead treating them as royalty, thereby placing himself on an equal or superior footing through magnanimity. This honorable treatment was later emulated by figures like Scipio Africanus and shaped the chivalric perception of Alexander.
Preview of Next Campaign Stages
Copied to clipboard!
(01:05:12)
  • Key Takeaway: The next phase of Alexander’s campaign involves the Mediterranean coast, including sieges at Tyre and Gaza, a venture into Egypt, and the crucial rematch with Darius at Gaugamela.
  • Summary: The immediate future involves Alexander moving from southeastern Turkey down the Mediterranean coastline. Key events include major sieges at Tyre and Gaza, and a significant visit to Egypt to consult an oracle. This path ultimately leads to the plains of Gaugamela, set to be the largest battle of Alexander’s career against Darius III.