Alexander the Great was a king (basileus) of the ancient Greek kingdom of Macedon[a] and a member of the Argead dynasty. He was born in Pella in 356 BC and succeeded his father Philip II to the throne at the age of 20. He spent most of his ruling years on an unprecedented military campaign through western Asia and northeast Africa, and by the age of thirty, he had created one of the largest empires of the ancient world, stretching from Greece to northwestern India. He was undefeated in battle and is widely considered one of history's most successful military commanders.
During his youth, Alexander was tutored by Aristotle until age 16. After Philip's assassination in 336 BC, he succeeded his father to the throne and inherited a strong kingdom and an experienced army. Alexander was awarded the generalship of Greece and used this authority to launch his father's pan-Hellenic project to lead the Greeks in the conquest of Persia.In 334 BC, he invaded the Achaemenid Empire (Persian Empire) and began a series of campaigns that lasted 10 years. Following the conquest of Anatolia, Alexander broke the power of Persia in a series of decisive battles, most notably the battles of Issus and Gaugamela. He subsequently overthrew Persian King Darius III and conquered the Achaemenid Empire in its entirety. At that point, his empire stretched from the Adriatic Sea to the Beas River.
Alexander endeavoured to reach the "ends of the world and the Great Outer Sea" and invaded India in 326 BC, winning an important victory over the Pauravas at the Battle of the Hydaspes. He eventually turned back at the demand of his homesick troops, dying in Babylon in 323 BC, the city that he planned to establish as his capital, without executing a series of planned campaigns that would have begun with an invasion of Arabia. In the years following his death, a series of civil wars tore his empire apart, resulting in the establishment of several states ruled by the Diadochi, Alexander's surviving generals and heirs.
Alexander's legacy includes the cultural diffusion and syncretism which his conquests engendered, such as Greco-Buddhism. He founded some twenty cities that bore his name, most notably Alexandria in Egypt. Alexander's settlement of Greek colonists and the resulting spread of Greek culture in the east resulted in a new Hellenistic civilization, aspects of which were still evident in the traditions of the Byzantine Empire in the mid-15th century AD and the presence of Greek speakers in central and far eastern Anatolia until the Greek genocide of the 1920s. Alexander became legendary as a classical hero in the mould of Achilles, and he features prominently in the history and mythic traditions of both Greek and non-Greek cultures. He was undefeated in battle and became the measure against which military leaders compared themselves. Military academies throughout the world still teach his tactics. He is often ranked among the most influential people in history.
A mural in Pompeii, depicting the marriage of Alexander to Barsine (Stateira) in 324 BC; the couple are apparently dressed as Ares and Aphrodite. Alexander married three times: Roxana, daughter of the Sogdian nobleman Oxyartes of Bactria, out of love; and the Persian princesses Stateira II and Parysatis II, the former a daughter of Darius III and latter a daughter of Artaxerxes III, for political reasons. He apparently had two sons, Alexander IV of Macedon by Roxana and, possibly, Heracles of Macedon from his mistress Barsine. He lost another child when Roxana miscarried at Babylon.
Alexander also had a close relationship with his friend, general, and bodyguard Hephaestion, the son of a Macedonian noble. Hephaestion's death devastated Alexander. This event may have contributed to Alexander's failing health and detached mental state during his final months.
Alexander's sexuality has been the subject of speculation and controversy in modern times. The Roman era writer Athenaeus says, based on the scholar Dicaearchus, who was Alexander's contemporary, that the king "was quite excessively keen on boys", and that Alexander sexually embraced his eunuch Bagoas in public. This episode is also told by Plutarch, probably based on the same source. None of Alexander's contemporaries, however, are known to have explicitly described Alexander's relationship with Hephaestion as sexual, though the pair was often compared to Achilles and Patroclus, whom classical Greek culture painted as a couple. Aelian writes of Alexander's visit to Troy where "Alexander garlanded the tomb of Achilles, and Hephaestion that of Patroclus, the latter hinting that he was a beloved of Alexander, in just the same way as Patroclus was of Achilles." Some modern historians (e.g., Robin Lane Fox) believe not only that Alexander's youthful relationship with Hephaestion was sexual, but that their sexual contacts may have continued into adulthood, which went against the social norms of at least some Greek cities, such as Athens, though some modern researchers have tentatively proposed that Macedonia (or at least the Macedonian court) may have been more tolerant of homosexuality between adults.
Green argues that there is little evidence in ancient sources that Alexander had much carnal interest in women; he did not produce an heir until the very end of his life. However, Ogden calculates that Alexander, who impregnated his partners thrice in eight years, had a higher matrimonial record than his father at the same age. Two of these pregnancies — Stateira's and Barsine's — are of dubious legitimacy.