The son of Philip II of Macedon and Olympias, he had Aristotle as his tutor and was given a classical education. Alexander had no part in the murder of his father, although he may have resented him because he neglected Olympias for another wife. He succeeded to the throne in 336 B.C. and immediately showed his talent for leadership by quieting the restive cities of Greece, then putting down uprisings in Thrace and Illyria. Thebes revolted on a false rumor that Alexander was dead. The young king rushed south and sacked the city, sparing only the temples and Pindar's house.

Greece and the Balkan Peninsula secured, Alexander then crossed (334) the Hellespont (now the Dardanelles) and, as head of an allied Greek army, undertook the war on Persia that his father had been planning. The march he had begun was to be one of the greatest in history. At the Granicus River (near the Hellespont) he met and defeated a Persian force and moved on to take Miletus and Halicarnassus. For the first time Persia faced a united Greece, and Alexander saw himself as the spreader of Panhellenic ideals. Having taken most of Asia Minor, he entered (333) N Syria and there in the battle of Issus met and routed the hosts of Darius III of Persia, who fled before him.

Alexander, triumphant, now envisioned conquest of the whole of the Persian Empire. It took him nearly a year to reduce Tyre and Gaza, and in 332, in full command of Syria, he entered Egypt. There he met no resistance. When he went to the oasis of Amon he was acknowledged as the son of Amon-Ra, and this may have contributed to a conviction of his own divinity. In the winter he founded Alexandria, perhaps the greatest monument to his name, and in the spring of 331 he returned to Syria, then went to Mesopotamia where he met Darius again in the battle of Guagamela. The battle was hard, but Alexander was victorious. He marched S to Babylon, then went to Susa and on to Persepolis, where he burned the palaces of the Persians and looted the city.

He was now the visible ruler of the Persian Empire, pursuing the fugitive Darius to Ecbatana, which submitted in 330, and on to Bactria. There the satrap Bessus, a cousin of Darius, had the Persian king murdered and declared himself king. Alexander went on through Bactria and captured and executed Bessus. He was now in the regions beyond the Oxus River (the present-day Amu Darya), and his men were beginning to show dissatisfaction. In 330 a conspiracy against Alexander was said to implicate the son of one of his generals, Parmenion; Alexander not only executed the son but also put the innocent Parmenion to death. This act and other instances of his harshness further alienated the soldiers, who disliked Alexander's assuming Persian dress and the manner of a despot.

Nevertheless Alexander conquered all of Bactria and Sogdiana after hard fighting and then went on from what is today Afghanistan into N India. Some of the princes there received him favorably, but at the Hydaspes (the present-day Jhelum River) he met and defeated an army under Porus. He overran the Punjab, but there his men would go no farther. He had built a fleet, and after going down the Indus to its delta, he sent Nearchus with the fleet to take it across the unknown route to the head of the Persian Gulf, a daring undertaking. He himself led his men through the desert regions of modern Baluchistan, S Afghanistan, and S Iran. The march, accomplished with great suffering, finally ended at Susa in 324.

At Susa Alexander found that many of the officials he had chosen to govern the conquered lands had indulged in corruption and misrule. Meanwhile certain antagonisms had developed against Alexander; in Greece, for instance, many decried his execution of Aristotle's nephew, the historian Callisthenes, and the Greek cities resented his request that they treat him as a god. Alexander's Macedonian officers balked at his attempt to force them to intermarry with the Persians (he had himself married Roxana, a Bactrian princess, as one of his several wives), and they resisted his Eastern ways and his vision of an empire governed by tolerance. There was a mutiny, but it was put down. In 323, Alexander was planning a voyage by sea around Arabia when he caught a fever and died at 33. After his death his generals fell to quarreling about dividing the rule (see Diadochi). His only son was Alexander Aegus, born to Roxana after Alexander's death and destined for a short and pitiful life.

Whether or not Alexander had plans for a world empire cannot be determined. He had accomplished greater conquests than any before him, but he did not have time to mold the government of the lands he had taken. Incontestably, he was one of the greatest generals of all time and one of the most powerful personalities of antiquity. He influenced the spread of Hellenism throughout the Middle East and into Asia, establishing city-states modeled on Greek institutions that flourished long after his death. There are many legends about him, e.g., his feats on his horse Bucephalus and his cutting of the Gordian knot. The famous Greek sculptor Lysippus did several studies of Alexander.