Battles & Wars › Greece, Rome & Han › Conquests of Alexander the Great
Alexander the Great
356–323 BC; king from 336 BC· Person· Europe
Well documentedSolid records, physical evidence or scientific consensus.
Macedonian king who conquered the Persian Empire and reached India in about 11 years without losing a major battle.
See it on the Battles & Wars map →What happened
Son of Philip II and tutored by Aristotle, Alexander became king at 20 when Philip was murdered in 336 BC. He crushed a Theban revolt, then invaded Persia in 334 BC. Leading the Companion cavalry himself, he won at the Granicus, Issus and Gaugamela, took Tyre and Gaza by siege, and founded many cities, several named Alexandria. He died in Babylon in 323 BC, aged 32, and his generals split the empire among themselves.
Why it matters
He spread Greek language and culture from Egypt to Afghanistan, beginning the Hellenistic age, and became the standard later conquerors, from Caesar to Napoleon, measured themselves against.
Legacy and how we know
Arrian's history, written over 400 years later but based on lost memoirs by his officers; Plutarch, Diodorus and Curtius; his coins; and inscriptions and city ruins across his empire.
Still debated
His cause of death, fever, poison or illness worsened by heavy drinking, is unknown, as is his tomb's location. Historians argue whether he was a visionary or a ruthless conqueror.
Inside this (1)
Connections (6)
▸Alexander the Great led the Conquests of Alexander the GreatWell documented
The connection
Alexander inherited his father's army and plan to invade Persia, but the scale was his own. He led from the front, combined pike phalanx, cavalry and siege engineers, and kept going past the Persian Empire's borders into India until his troops refused to go farther.
When and how
From the Hellespont in 334 BC to the Beas River in India in 326 BC, then back to Babylon, where he died in 323 BC.
How we know
Arrian and other ancient historians, cities he founded such as Alexandria in Egypt, coins struck in his name, and inscriptions across the region.
Debates and open questions
Whether he planned world conquest from the start or kept setting new goals is debated, as is how much credit belongs to Philip's army.
▸Alexander the Great commanded the wing that broke Thebes at the Battle of ChaeroneaWell documented
The connection
At 18, Alexander commanded the Macedonian left wing, facing the Thebans. When the Greek line stretched and opened a gap, his attack broke through and destroyed the Theban Sacred Band. It was his first major command and proved him to the army.
When and how
Chaeronea in Boeotia, central Greece, August 2, 338 BC, under his father, Philip II.
How we know
Diodorus says Alexander broke the Theban line first; Plutarch says he was first to charge the Sacred Band. Both wrote centuries later.
Debates and open questions
Whether he led a cavalry charge, as often told, or infantry is debated; the sources never clearly say.
▸Alexander the Great won his greatest victory at the Battle of GaugamelaWell documented
The connection
Darius III chose a flat plain where his much larger army and scythed chariots could deploy. Alexander angled his line to the right, stretching the Persian line until a gap opened, then led his Companion cavalry through it toward Darius, who fled. Persian resistance collapsed.
When and how
Gaugamela, near Mosul in northern Iraq, October 1, 331 BC.
How we know
Arrian and other ancient historians describe the battle; a Babylonian astronomical diary records Darius's defeat and helps fix the date.
Debates and open questions
Persian army size is unknown: ancient claims of up to a million are impossible, and modern estimates run from about 50,000 to 120,000.
▸Alexander the Great inspired the ambitions of Julius CaesarMostly agreed
The connection
Educated Romans grew up on stories of Alexander. Suetonius says Caesar, in his early 30s, sighed before Alexander's statue in Spain because he had achieved nothing memorable at the age Alexander had conquered the world. In that telling, Alexander was the yardstick Caesar measured his own career against.
When and how
Gades (modern Cádiz), Spain, around 69 BC, when Caesar was a junior official (quaestor).
How sure are we?
Suetonius tells it, writing more than 150 years later; Plutarch gives a version with Caesar weeping over a history of Alexander, and paired the two men in his 'Parallel Lives'.
Debates and open questions
The story may be a moralizing legend, and how much Alexander actually guided Caesar's choices, rather than Roman politics, is unknowable.
▸Alexander the Great was a model for Napoleon BonaparteMostly agreed
The connection
Napoleon read Plutarch's Alexander as a boy and listed him among the great captains every officer should study. His 1798 invasion of Egypt, with hopes of striking at British India, echoed Alexander's march east. He claimed the art of war could be learned from such commanders' campaigns.
When and how
Military school at Brienne in the 1780s; Egypt and Syria in 1798–1799; and Napoleon's later recollections in exile on Saint Helena.
How sure are we?
Napoleon's recorded maxims name Alexander among seven great commanders to study, and his 1799 letter to Tipu Sultan of Mysore shows his hopes of reaching India.
Debates and open questions
Whether Napoleon truly modeled himself on Alexander or used the comparison for propaganda is debated; probably both.
▸Alexander the Great defeated King Porus at Battle of the HydaspesWell documented
The connection
Alexander kept Porus guessing for weeks with feints along the river, then crossed upstream on a stormy night. He drew Porus's cavalry into a fight, sent a cavalry wing around behind them, and let his phalanx wear down the elephants. Afterward he restored Porus as king over a larger realm, gaining a loyal ally.
When and how
The Hydaspes (Jhelum) River in Punjab, May 326 BC; Alexander, his cavalry commander Coenus, and King Porus of the Paurava.
How we know
Arrian, drawing on lost accounts by Ptolemy and Aristobulus, who served with Alexander, describes the battle in detail.
Debates and open questions
The crossing site is uncertain, and why Alexander rewarded Porus, admiration or practical need for a strong local ally, is debated.