Alexander III of Macedon (Ancient Greek: Ἀλέξανδρος, romanized: Aléxandros; 20 11 June 323 BC), most commonly known as Alexander the Great, was king of the ancient Greek kingdom of Macedon. He succeeded his father Philip II to the throne in 336 BC at the age of 20, and spent most of his reign conducting a lengthy military campaign throughout Asia and Egypt. By the age of 30, he had created one of the largest empires in history, stretching from Greece to northwestern India. He was undefeated in battle and is widely considered to be one of history's greatest and most successful military commanders.
Born in Pella, Macedon, Alexander was tutored by philosopher and polymath Aristotle until the age of 16. In 335 BC, shortly after assuming the throne of Macedon, he launched a campaign in the Balkans and reasserted control over Thrace and parts of Illyria before marching on the city of Thebes, which was subsequently destroyed. Alexander then assumed leadership of the League of Corinth, created by his father.
With this authority over all Greeks he launched a pan-Hellenic invasion of the Persian Achaemenid Empire in 334 BC, and with it began a series of campaigns which lasted for ten years.