Alexander III, known historically as Alexander the Great, was the undefeated ruler of Macedon who quelled uprisings in Thebes, Athens and Thessaly upon his father's death and conquered Persia, Anatolia, Syria, Phoenicia, Judea, Gaza, Egypt, Bactria and Mesopotamia. During his reign, he expanded the boundaries of his empire as far as Punjab, India.
Alexander the Great is considered one of the most successful military commanders of all time. By the time of his death at age 32, he had conquered most of the world that was known to the ancient Greeks. He assumed the kingship of Macedon in 336 BC upon the death of his father, Philip II of Macedon, and ruled until his own death under suspicious circumstances in 323 BC. His 13-year rule was defined by constant war and his desire to expand his empire to the "ends of the world and the Great Outer Sea."
Alexander's military advancement can be separated into three stages: the Balkan, Persian and Indian campaigns. His first order of business upon taking the throne was to secure the borders of his country, with decisive battles at Mount Haemus in Thrace, Pelium and Thebes.
In 334 BC, he crossed the Hellespont into Asia for a 10-year war against Darius III and the First Persian Empire, also known as the Achaemenid Persian Empire. He defeated the Persians and took control of the empire's extensive land holdings.
Alexander the Great eventually turned his military attentions to the Indian subcontinent and made significant inroads until his untimely death from sickness, despite a disgruntled army that wanted to return home.