Battles & Wars › Greece, Rome & Han
Conquests of Alexander the Great
334–323 BC· War· Middle East & Africa
Well documentedSolid records, physical evidence or scientific consensus.
Alexander III of Macedon conquered the Persian Empire and marched as far as northwest India in about eleven years.
See it on the Battles & Wars map →What happened
Inheriting a superb army and a planned Persian war from his father, Philip II, Alexander crossed into Asia in 334 BC with about 40,000 men. He won at the Granicus, Issus and Gaugamela, took Egypt and founded Alexandria, and seized the Persian capitals. He pushed through Central Asia to the Indus, beating King Porus at the Hydaspes River in 326 BC, until his troops refused to go farther. He died in Babylon in 323 BC, aged 32.
Why it matters
His empire split among his generals within years, but it spread Greek language and cities from Egypt to Afghanistan, creating the Hellenistic world that Rome inherited.
How we know
Arrian's history, written about 450 years later from lost eyewitness accounts; Plutarch and others; coins, inscriptions, and Babylonian astronomical diaries recording Gaugamela and his death.
Still debated
How he died (fever, malaria, alcohol or poison) and what he ultimately intended are unknown; whether he was a visionary or a ruthless conqueror is debated.
Inside this (7)
Connections (11)
▸Trojan War inspired, through Homer's Iliad, the ambitions behind Conquests of Alexander the GreatMostly agreed
The connection
Alexander grew up on Homer and modeled himself on Achilles, whom his mother's family claimed as an ancestor. Crossing into Asia in 334 BC, he visited Troy, honored Achilles' tomb and took armor said to date from the war. He reportedly kept a copy of the Iliad, annotated by his tutor Aristotle, on campaign.
When and how
Troy, northwest Turkey, spring 334 BC, at the start of Alexander's invasion of the Persian Empire.
How sure are we?
Arrian and Plutarch both describe the Troy visit and his devotion to the Iliad, drawing on earlier accounts now lost.
Debates and open questions
How much Homer drove his choices, versus Philip II's existing invasion plan and Macedonian politics, and how much later writers romanticized, is debated.
▸Phalanx (hoplite and Macedonian) powered Conquests of Alexander the GreatWell documented
The connection
Philip II's Macedonian phalanx, with pikes about 5–6 meters long, formed the steady center of Alexander's army. It pinned the enemy in place while the Companion cavalry struck the decisive blow: a 'hammer and anvil' combination that beat Persian armies from the Granicus to Gaugamela.
When and how
Macedon from about 359 BC under Philip II; used by Alexander across Persia, Egypt, Central Asia and India, 334–323 BC.
How we know
Arrian and other historians describe the pike phalanx in each major battle, and iron sarissa heads have been found at Macedonian sites such as Vergina.
Debates and open questions
Exact pike lengths, and how much Philip invented versus borrowed from Thebes, where he lived as a young hostage, are debated.
▸Achaemenid Persian Empire was conquered in Conquests of Alexander the GreatWell documented
The connection
Persia's wealth, roads and provincial system made it the prize. Alexander broke its field armies in three great battles, then took its capitals and treasuries. After Darius III was murdered by one of his own governors in 330 BC, Alexander presented himself as the Persian king's successor, keeping many governors and court customs.
When and how
Anatolia, the Levant, Egypt, Mesopotamia and Iran, 334–330 BC; Alexander against Darius III; Persepolis burned in 330 BC.
How we know
Greek histories, Babylonian records and the burn layer excavated at Persepolis confirm the conquest and its stages.
Debates and open questions
Whether burning Persepolis was planned revenge for Xerxes' burning of Athens or a drunken act is debated.
▸Peloponnesian War weakened the Greek cities before Conquests of Alexander the GreatMostly agreed
The connection
The war drained Athens and Sparta and was followed by decades of further Greek infighting, with Persia funding different sides. Divided, exhausted Greek cities could not stop Philip II of Macedon, who won at Chaeronea in 338 BC and left Alexander control of Greece and a ready army.
When and how
Greece, 404–338 BC: Spartan and then Theban dominance, ending with Philip II's victory at Chaeronea, Boeotia.
How sure are we?
Xenophon's Hellenica, Demosthenes' speeches warning against Philip, and Diodorus' history trace the decline and Macedon's rise.
Debates and open questions
Historians debate whether Macedon's rise owed more to Greek weakness or to Philip's own military and diplomatic skill.
▸Battle of Issus was a key early victory of Conquests of Alexander the GreatWell documented
The connection
Issus was Alexander's first victory over Darius himself. It opened the eastern Mediterranean coast, letting him capture the Phoenician ports that based Persia's fleet, and then Egypt. Capturing the Persian royal family also boosted his prestige as a would-be king of Asia.
When and how
Near the Pinarus River on the Gulf of Iskenderun, southeastern Turkey, November 333 BC.
How we know
All the main ancient histories describe the battle and its aftermath; the Alexander Mosaic from Pompeii probably shows it.
Debates and open questions
Whether Alexander should have chased Darius instead of turning south to Tyre and Egypt is still argued by military historians.
▸Conquests of Alexander the Great spread Greek culture later absorbed by Roman EmpireMostly agreed
The connection
Alexander's conquests planted Greek cities, language and art from Egypt to Afghanistan, creating the Hellenistic world. When Rome conquered the kingdoms his generals founded, from Macedon in 168 BC to Egypt in 30 BC, it absorbed that culture. Greek stayed the common language of the eastern empire, and Roman elites studied Greek philosophy and copied Greek art.
When and how
Eastern Mediterranean, from Alexander's death in 323 BC to Rome's annexation of Ptolemaic Egypt in 30 BC, through Rome's wars with Macedon and the Seleucid kings.
How sure are we?
Greek inscriptions and papyri across the eastern empire, Roman copies of Greek statues, and the poet Horace: 'Captive Greece took captive her savage conqueror.'
Debates and open questions
How much Greek influence Roman culture already had before these conquests, through Greek cities in southern Italy, is debated.
▸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.
▸Battle of Chaeronea gave Macedon the Greek base for the Conquests of Alexander the GreatWell documented
The connection
Chaeronea made Macedon master of Greece. Philip then formed the League of Corinth, a Greek alliance under Macedonian command, which voted for war on Persia in revenge for Xerxes's invasion. When Philip was murdered in 336 BC, Alexander inherited both the army and that mandate.
When and how
Corinth, 338–337 BC, where the Greek states except Sparta joined the league; an advance force crossed into Asia in 336 BC.
How we know
Diodorus and Arrian, plus a surviving inscription of the league's oath found in Athens.
Debates and open questions
Whether 'revenge' for Xerxes was a real goal or a slogan to win Greek support is debated; many Greeks resented Macedonian rule.
▸Battle of the Granicus was the first big victory of the Conquests of Alexander the GreatWell documented
The connection
The Granicus was the first clash after Alexander crossed into Asia. Victory showed that the Persian governors could not stop him locally, so Darius III himself had to raise a royal army. Sardis surrendered, and the Greek cities of western Anatolia came over.
When and how
The Biga Çayı river, northwest Turkey, May 334 BC, against an army of satraps and Greek mercenaries.
How we know
Arrian, Plutarch and Diodorus agree on the victory and its results, though they differ on the battle's details.
Debates and open questions
Some historians think the real Persian mistake was fighting at the river at all, instead of retreating and burning the land as their Greek commander Memnon advised.
▸Siege of Tyre (332 BC) was the hardest siege of Conquests of Alexander the GreatWell documented
The connection
Tyre took about seven months, Alexander's longest siege, and needed a causeway, siege towers and a borrowed fleet. Its fall gave him the Levant coast, ended Persian sea power, and opened the way to Egypt, which surrendered without a fight later that year.
When and how
Tyre, in modern Lebanon, 332 BC; Alexander and his engineers, among them the siege specialist Diades, against the city's defenders.
How we know
Every major ancient account of Alexander gives the siege long treatment, and the geology of Tyre's silted causeway confirms the scale of the work.
Debates and open questions
Some historians rank the siege of Gaza or the guerrilla war in Central Asia as equally hard; the ranking depends on whether you count time, losses or engineering.
▸Battle of the Hydaspes was the last great battle of Conquests of Alexander the GreatWell documented
The connection
The Hydaspes was Alexander's last major pitched battle. It cost his army heavily, and soon after, at the Hyphasis (Beas) River, his soldiers refused to march farther into India. Alexander turned back down the Indus, crossed the Gedrosian desert, and died in Babylon in 323 BC without fighting another battle on this scale.
When and how
Punjab, in modern Pakistan, May 326 BC; the mutiny at the Hyphasis followed later that summer.
How we know
Arrian, Curtius and Plutarch all describe the battle, then the mutiny and the turn homeward.
Debates and open questions
How far the battle's cost, rather than exhaustion, monsoon rains or reports of bigger Indian armies ahead, drove the mutiny is debated.