Conquests of Alexander the Great

The causes

His father, Philip II, had made Macedon the leading military power of Greece and prepared an expedition against Persia, to avenge the invasions of 480 BC. Philip was assassinated in 336, and Alexander, aged twenty, succeeded him. After securing his power in Greece, he set out in 334 to attack the empire of Darius III.

Greece was exhausted by decades of wars between city-states. In 338 BC, Philip II crushed at Chaeronea a coalition of Athens and Thebes, then in 337 BC founded the League of Corinth, which placed the Greek cities under his authority and planned a war against Persia. For the Greeks, Persia remained the hereditary enemy, and it had long financed cities hostile to Macedonia. When Alexander succeeded his father, he first had to suppress revolts in Greece and the Balkans; he destroyed Thebes in 335 BC to deter any new rebellion. The Macedonian treasury, enriched by the mines of Mount Pangaion, financed a solid army.

The course of the war

Alexander beat the Persians at the Granicus in 334, then Darius III at Issus in 333. He took Tyre in 332 after a long siege, entered Egypt, where he founded Alexandria, and crushed Darius again at Gaugamela in 331. Babylon and Susa fell; Persepolis, the ceremonial capital, was burned in 330. Darius was killed by one of his own officers.

Alexander continued into Central Asia and then India, where he beat King Porus on the Hydaspes in 326. His exhausted soldiers refused to go further. He turned back and died in Babylon, in June 323, without having named an heir.

The Macedonian army rested on a heavy infantry phalanx armed with long pikes, the sarissas, and on an elite cavalry, the Companions, which struck the enemy's weak points. Cities were taken with siege engines: Gaza fell in 332 BC after a two-month siege. In India, at the Hydaspes, Porus's elephants impressed the soldiers, but the Macedonian cavalry managed to outflank them and throw them into disorder. This combination of infantry, cavalry and artillery partly explains the speed of the victories.

In Central Asia, Alexander faced fierce resistance. In 327 BC he took the Sogdian Rock, a fortress reputed impregnable, and then married Roxana, daughter of a local noble, in order to consolidate his power. He also adopted part of the Persian court ceremonial, notably prostration before the king, which provoked opposition among many Macedonians. The historian Callisthenes, nephew of Aristotle, refused this practice; he was accused of conspiracy and executed shortly afterwards. This affair reveals the tension between Macedonians attached to their traditions and a king who sought to govern a multi-ethnic empire.

The return was a gruelling ordeal: crossing the Gedrosian desert in 325 BC cost the troops dearly. In 324 BC, at Susa, Alexander organised mass weddings, and several dozen Macedonian officers married women of the Persian nobility; he himself married Stateira, daughter of Darius III. This policy of fusion angered the Macedonian veterans, who mutinied at Opis before being reconciled with the king. Alexander then prepared a new expedition, but his death interrupted it at Babylon.

The consequences

With no adult heir, the empire was divided among his generals, the Diadochi, into kingdoms such as that of the Ptolemies in Egypt and that of the Seleucids in Asia. The Hellenistic period began, during which Greek became the language of exchange from Egypt to Central Asia. Dozens of cities, such as Alexandria, were founded. The blending of Greek, Egyptian and Eastern cultures left a lasting mark on the region.

The Diadochi kingdoms founded lasting capitals and cultures: Alexandria, in Egypt, where the Museum and the Library attracted scholars and philosophers; the Greco-Bactrian kingdoms in Central Asia, and later the Indo-Greek kingdoms in the north-west of India. Historians still debate Alexander's real aim, between a project of merging peoples and simple conquest. His main sources, Arrian, Plutarch or Quintus Curtius, wrote several centuries after the events, drawing on lost testimonies. In Persian and Islamic literature he became Iskandar, a legendary figure, while the European tradition made him an ideal hero of the Middle Ages.

Timeline

1. 334 BCAlexander defeats the Persians at the Granicus
2. 333 BCVictory over Darius III at Issus
3. 331 BCDecisive victory at Gaugamela
4. 326 BCVictory over Porus at the Hydaspes, in India
5. 323 BCDeath of Alexander in Babylon

Key figures

• Alexander the Great, king of Macedon, conqueror of the Persian empire
• Philip II, his father, who created the Macedonian army
• Darius III, last king of the Achaemenid Persian empire
• Aristotle, philosopher, Alexander's tutor in his youth