Summary
Highlights
Alexander, King of Macedonia, embarked on one of history's greatest military campaigns in 334 BC against the Persian Empire. At 20, his brilliant leadership led to numerous victories, carving out a vast empire in 10 years and leaving an indelible impact on history, earning him the title 'Alexander the Great'.
Ancient Greece, from 500 BC, saw significant advancements in art, philosophy, and warfare. Athens and Sparta, its great city-states, united to repel a Persian invasion in 480 BC, with notable battles at Thermopylae and Salamis. After decades of internal conflict, the Greek city-states were exhausted, making them vulnerable to the rising power of Macedonia under King Philip II, Alexander's father. Philip's military reforms, including the sarissa and the phalanx, enabled him to conquer and unite Greece, forming the Hellenic League. Philip's assassination led to 20-year-old Alexander inheriting his grand plan to invade Persia.
Alexander secured his position by executing rivals and crushing rebellions, notably destroying Thebes. In spring 334 BC, he launched his campaign against Persia, leading an army of 40,000 Greeks. The Macedonian Army comprised 9,000 phalangites armed with 18-foot sarissas, 3,000 elite hypaspists, 7,000 Greek allies, 5,000 mercenaries, and various skirmishers. The Companion Cavalry, 1,800 elite horsemen led by Alexander himself, formed the army's shock troops.
Persian satraps in Asia Minor, ignoring advice to use a scorched-earth strategy, decided to face Alexander at the River Granicus. The Persian army, with 10,000 cavalry and Greek mercenaries, formed a defence. Alexander, slightly outnumbered but eager to attack, deployed his forces and ordered an immediate assault across the river. Despite fierce resistance and near-death experiences for Alexander, the Macedonian phalanx crossed, routing most of the Persian cavalry. Alexander then massacred the Greek mercenaries perceived as traitors, securing a major victory and opening Asia Minor to his forces.
After Granicus, Alexander secured Sardis and targeted Persian naval bases in Miletus and Halicarnassus, conquering them. He then continued into Lycia and Phrygia, where he famously 'untied' the Gordian Knot. Memnon of Rhodes, a Greek general in Persian service, briefly threatened Alexander's flank with naval attacks but died suddenly. In 333 BC, Alexander led his army into Cilicia, moving towards Syria.
King Darius III, with a larger army, trapped Alexander's forces near Issus, a narrow coastal plain. This terrain, however, prevented Darius from fully utilising his numerical superiority. Alexander's right wing, led by himself, charged the Persian left, causing disarray. The Macedonian phalanx, facing Darius's Greek mercenaries in the centre, struggled briefly until Alexander's intervention. Darius fled, leading to a Persian rout and a decisive victory for Alexander, who captured Darius's family.
Following Issus, Alexander subdued Phoenicia, capturing the island-city of Tyre after a seven-month siege, and Gaza. He then advanced to Egypt, where he was welcomed as a liberator from Persian rule and crowned Pharaoh. He founded Alexandria and visited the Oracle of Siwah, where he was reportedly affirmed as the 'Son of Amun', king of the gods.
In 331 BC, King Agis of Sparta, with Persian support, led a revolt against Macedonian rule in Greece. Alexander's commander Antipater crushed the Spartan army at Megalopolis, securing Alexander's base. Darius III offered Alexander a fortune, his daughter, and half the empire for peace, but Alexander, convinced of his destiny to rule the world, rejected the offer, aiming to conquer the entire empire.
Alexander headed to Gaugamela in 331 BC for a final confrontation with Darius. Darius chose open ground to exploit his numerical advantage, estimated between 50,000 and 80,000 troops, including chariots and war elephants, against Alexander's smaller force. Alexander used a feigned flanking manoeuvre to draw Persian troops from their centre. His cavalry then charged, followed by the phalanx. Darius fled once more, causing his army to collapse. Despite a critical situation on Parmenion's left flank, Alexander regrouped and reinforced, securing a complete victory with minimal losses.
Victory at Gaugamela opened the road to Babylon and Susa, where Alexander was recognised as the new ruler. He faced resistance at the Persian Gates but bypassed and destroyed the defenders. In 330 BC, he reached Persepolis, the ceremonial capital, and ordered its pillaging and burning as revenge for Persia's invasion of Greece. Darius fled to Media but was murdered by his own governor, Bessus. Alexander ordered Darius buried with his ancestors and began consolidating his new empire, preparing to pursue Bessus.
Alexander continued his eastern march to subjugate the provinces and eliminate Bessus. He crushed a revolt in Aria, founding Alexandria Ariana (modern Herat). At Phrada, he executed Philotas and Parmenion on suspicion of a plot. In 329 BC, he founded Alexandria Arachosia (Kandahar) and eventually captured Bessus, sending him to Persia for execution. He then faced Sogdian resistance, establishing Alexandria-Eschate (Alexandria 'the Furthest') on the Jaxartes River, marking the eastern limit of the Persian Empire and ending Scythian raids.
Macedonian troops grew discontent with Alexander's endless conquest and adoption of Persian customs. Alexander killed Cleitus the Black in a drunken rage. His attempt to enforce 'proskynesis' (prostration) on his Greek soldiers, which they considered blasphemous, was met with resistance. Another assassination plot was uncovered in Bactria, leading to the execution of Hermolaus and the imprisonment and death of Callisthenes, Alexander's historian.
In 327 BC, Alexander married Roxana, a Bactrian princess, a move that helped quell local revolts. He then advanced into modern Pakistan and India, crossing the Hindu Kush mountains. His army fought through the Aspasii and Assaceni, taking Massaga after a fierce siege. Allied with the ruler of Taxila, Alexander faced King Porus at the Battle of the Hydaspes, a costly victory that granted him control of Punjab.
At the River Hyphasis (Beas), Alexander's army, weary after years of campaigning, mutinied and refused to advance further into India. Alexander, furious but forced to concede, led his army back. During the return journey, he defeated the Mahlians but was severely wounded. Part of his army returned by sea under Nearchus, while Alexander led the rest through the Gedrosian desert, enduring immense hardship and losses due to heat and lack of supplies.
Upon returning to Persia, Alexander executed corrupt governors. At Susa, he promoted integration through mass marriages between Macedonian officers and Persian noblewomen, and himself married two Persian princesses. He ordered Persion youths trained in Macedonian warfare, but his troops mutinied at Opis due to his perceived favouritism towards Persians, leading to an emotional reconciliation. In Ecbatana, his closest friend Hephaestion died of fever, causing Alexander immense grief. Alexander campaigned successfully against the Cossaeans. In Babylon, planning campaigns to Arabia, he fell ill and died at 32 in 323 BC. The cause remains debated, ranging from natural illness to poison.
Alexander died undefeated in battle, celebrated as a brilliant and daring commander. His decade-long campaign created one of history's largest, yet unstable, empires. With no clear succession plan, his generals, the Diadochi, fought amongst themselves, leading to the murder of his wife Roxana and son. His achievements ushered in the Hellenistic Age, spreading Greek culture, art, science, and language across his former territories. Although many successor kingdoms were short-lived, Alexander's impact on history remains profound.