In 335 BC, shortly after his assumption of kingship over Macedon, he campaigned in the Balkans and reasserted control over Thrace and parts of Illyria before marching on the city of Thebes, which was subsequently destroyed in battle.

Alexander endeavored to reach the "ends of the world and the Great Outer Sea" and invaded India in 326 BC, achieving an important victory over Porus, an ancient Indian king of present-day Punjab, at the Battle of the Hydaspes.

Due to the mutiny of his homesick troops, he eventually turned back at the Beas River and later died in 323 BC in Babylon, the city of Mesopotamia that he had planned to establish as his empire's capital.

Alexander III was born in Pella, the capital of the Kingdom of Macedon,[10] on the sixth day of the ancient Greek month of Hekatombaion, which probably corresponds to 20 July 356 BC (although the exact date is uncertain).

[15] According to the ancient Greek biographer Plutarch, on the eve of the consummation of her marriage to Philip, Olympias dreamed that her womb was struck by a thunderbolt that caused a flame to spread "far and wide" before dying away.

[41] At the wedding of Cleopatra, whom Philip fell in love with and married, she being much too young for him, her uncle Attalus in his drink desired the Macedonians would implore the gods to give them a lawful successor to the kingdom by his niece.

[47] In the 24th day of the Macedonian month Dios, which probably corresponds to 25 October 336 BC,[48][49] while at Aegae attending the wedding of his daughter Cleopatra to Olympias's brother, Alexander I of Epirus, Philip was assassinated by the captain of his bodyguards, Pausanias.

During his brief months in Egypt, he reformed the taxation system on the Greek models and organized the military occupation of the country, but in early 331 BC he left for Asia in pursuit of the Persians.

[83] To legitimize taking power and be recognized as the descendant of the long line of pharaohs, Alexander made sacrifices to the gods at Memphis and went to consult the famous oracle of Amun-Ra at the Siwa Oasis in the Libyan desert,[82] at which he was pronounced the son of the deity Amun.

Possible causes include a drunken accident or deliberate revenge for the burning of the Acropolis of Athens during the Second Persian War by Xerxes;[95] Plutarch and Diodorus allege that Alexander's companion, the hetaera Thaïs, instigated and started the fire.

[96] Plutarch recounts an anecdote in which Alexander pauses and talks to a fallen statue of Xerxes as if it were a live person: Shall I pass by and leave you lying there because of the expeditions you led against Greece, or shall I set you up again because of your magnanimity and your virtues in other respects?

[106] However, as basic forms of community life and the general structure of government were maintained and resuscitated by Alexander under his own rule, he, in the words of the Iranologist Pierre Briant "may therefore be considered to have acted in many ways as the last of the Achaemenids.

[112] During the long rule of the Achaemenids, the elite positions in many segments of the empire including the central government, the army, and the many satrapies were specifically reserved for Iranians and to a major degree, Persian noblemen.

[107] Pierre Briant explains that Alexander realized that it was insufficient to merely exploit the internal contradictions within the imperial system as in Asia Minor, Babylonia or Egypt; he also had to (re)create a central government with or without the support of the Iranians.

[107] However, Alexander's eventual decision to burn the Achaemenid palace at Persepolis in conjunction with the major rejection and opposition of the "entire Persian people" made it impracticable for him to pose himself as Darius' legitimate successor.

[123] The silver coinage had a beardless head of Heracles wearing a lionskin headdress on the obverse and Zeus aetophoros ('eagle bearer') enthroned with a scepter in his left hand, on the reverse.

The elephant had gold rings around its tusks and an inscription was on them written in Greek: "Alexander the son of Zeus dedicates Ajax to the Helios" (ΑΛΕΞΑΝΔΡΟΣ Ο ΔΙΟΣ ΤΟΝ ΑΙΑΝΤΑ ΤΩΙ ΗΛΙΩΙ).

[139]Alexander tried to persuade his soldiers to march farther, but his general Coenus pleaded with him to change his opinion and return; the men, he said, "longed to again see their parents, their wives and children, their homeland".

Along the way his army conquered the Malhi (in modern-day Multan) and other Indian tribes; while besieging the Mallian citadel, Alexander suffered a near-fatal injury when an arrow penetrated his armor and entered his lung.

[155] In the second account, Diodorus recounts that Alexander was struck with pain after downing a large bowl of unmixed wine in honour of Heracles followed by 11 days of weakness; he did not develop a fever, instead dying after some agony.

[156] Another theory is that his successors wilfully or erroneously misheard "tôi Kraterôi"—"to Craterus", the general leading his Macedonian troops home and newly entrusted with the regency of Macedonia.

[192] Diodorus, Curtius and Justin offered the more plausible story that Alexander passed his signet ring to Perdiccas, a bodyguard and leader of the companion cavalry, in front of witnesses, thereby nominating him.

After the assassination of Perdiccas in 321 BC, Macedonian unity collapsed, and 40 years of war between "The Successors" (Diadochi) ensued before the Hellenistic world settled into three stable power blocs: Ptolemaic Egypt, Seleucid Syria and East, and Antigonid Macedonia.

[200] The Macedonian phalanx, armed with the sarissa, a spear 6 metres (20 ft) long, had been developed and perfected by Philip II through rigorous training, and Alexander used its speed and manoeuvrability to great effect against larger but more disparate Persian forces.

[206] Ancient authors recorded that Alexander was so pleased with portraits of himself created by Lysippos that he forbade other sculptors from crafting his image; scholars today, however, find the claim dubious.

[259] According to Diodorus Siculus, Alexander accumulated a harem in the style of Persian kings, but he used it rather sparingly, "not wishing to offend the Macedonians",[260] showing great self-control in "pleasures of the body".

"[274] Hellenization was coined by the German historian Johann Gustav Droysen to denote the spread of Greek language, culture, and population into the former Persian empire after Alexander's conquest.

[299] In 39, Caligula performed a spectacular stunt by ordering a temporary floating bridge to be built using ships as pontoons, stretching for over two miles from the resort of Baiae to the neighbouring port of Puteoli.

[302] The diffusion of Greek culture and language cemented by Alexander's conquests in West Asia and North Africa served as a "precondition" for the later Roman expansion into these territories and entire basis for the Byzantine Empire, according to Errington.

[313] Firdausi's Shahnameh ("The Book of Kings") includes Alexander in a line of legitimate Persian shahs, a mythical figure who explored the far reaches of the world in search of the Fountain of Youth.