Alexander III, more commonly known as Alexander the Great, was born in 356 BCE to King Philip II of Macedonia. His mother was Olympias, princess of the kingdom of Epirus. The Argead dynasty to which his father Philip belonged claimed descent from the hero Heracles, while his mother's family believed themselves descended from Neoptolemus, the son of the hero Achilles.
What was so great about Alexander?
Macedonian kings were often engaged in wars to secure the borders against incursions from their neighbours or to suppress rebellions in their own highland provinces. Economic and political developments were slow in coming. After Philip became ruler in ca. 360 BCE he fully pacified the highland provinces, decisively defeated the Illyrians, conquered the Thracians and annexed their lands. He turned Macedonia into a well-organised military powerhouse.
In 338 BCE Philip reaped the fruits of careful diplomacy and military innovations when he defeated Athens and Thebes at the battle of Chaeronea. He united the Greeks, Sparta alone excepted, under the League of Corinth of which he was the Hegemon or leader. He next planned to invade the Persian Empire. Philip’s career, however, was cut short when one of his bodyguards assassinated him in 336 BCE on the eve of the full-scale invasion of Persia.
Alexander had acted as regent of Macedonia, had put down rebellion in Thrace at age 16, and led the cavalry charge that broke the line of the Theban Sacred Band at Chaeronea at 18.
JLMC CC24 Bust of Alexander the Great
Now, just 20 years old, he ascended to the throne of Macedonia.
After suppressing rebellions in the North and in Greece itself, Alexander crossed the Hellespont into Asia in 334 BCE. In the Battle of Issus in 333 BCE Alexander achieved a spectacular victory over Darius III. After the Battle of Gaugamela in October of 331 BCE, when he defeated Darius III a second time, Alexander effectively became King of Persia at just 25 years of age. In the years 330 to 328 he conquered the eastern third of the Persian Empire. He campaigned in northern India in 327-5 BCE, going far beyond what the Persians had held.
In 323 Alexander died at Babylon of an unidentifiable illness, possibly a combination of any number of tropical diseases, imperfectly healed wounds (like the arrow in the lung which he had received in India), alcohol consumption, and the stress of 13 years of hard campaigning. By the time of his death, just a month before his thirty-third birthday, he had conquered the largest empire the world had yet seen. Formally he was succeeded by his brother, Philip III Arrhidaeus, and his son Alexander IV who was born shortly after his death. In reality, however, the rule of the empire fell to various people, not just his generals (the so-called Diadochi or 'successors'), but also, in a first for the ancient Greek world, to a few ambitious women too, in particular his mother Olympias and his half-sister Eurydice.
Alexander’s campaign had spread Greek culture across Asia, and when the Diadochi took control of the old Persian Empire masses of Greeks emigrated to it. Gymnasia and theatres were built all over Asia, a simplified version of Greek (Koine) became the most common spoken language in many of the cities, and Greek-style philosophy and mathematics were taken up throughout the East. This ensured the dominance of a new type of Greek culture conventionally termed 'Hellenistic'.