Photograph by Universal History Archive, Getty
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The legend of this painting, "Alexander cutting the Gordian Knot," is that in 333 B.C. at Gordium, Phrygia, Alexander the Great, unable to untie the knot, sliced it with his sword. Jean-Simon Berthelemy (1743-1811), a French history painter, painted this oil on canvas.

Photograph by Universal History Archive, Getty

Who was Alexander the Great?

The son of a king, Alexander was a brilliant military leader who conquered most of the known world, but he wasn't much of a diplomat.

The vast Eurasian empire that Alexander the Great (356–323 B.C.) forged was not long-lasting, but his heroic deeds were legendary. Alexander was the son of King Philip II of Macedonia, a realm north of Greece. When Athens was left unstable by the interminable Peloponnesian War, Philip saw an opening and took it; he subdued Greece around 339 B.C.

While Philip was at war, Alexander studied math, archery, and other subjects with tutors, including the renowned philosopher Aristotle. According to Greek author Plutarch, Alexander kept a copy of Homer’s Iliad, annotated by Aristotle, “with his dagger under his pillow, declaring that he esteemed it a perfect portable treasure of all military virtue and knowledge.”

The precocious Alexander was already a seasoned commander in the Macedonian army when he became king at the age of 20 in 336 B.C., after his father’s assassination. In one of his most decisive moves, the young monarch forcefully proved his authority over rebellious Greeks by storming the defiant city of Thebes, slaughtering thousands of residents and enslaving the rest.

Persian conquest

In 334 B.C., Alexander set out to conquer the Persian Empire, which had waned in power but remained a behemoth. Alexander’s army numbered fewer than 40,000 men, mostly Macedonian and fiercely loyal. The versatile force included cavalry and heavily armed foot soldiers, who wielded spears and formed a phalanx, advancing relentlessly behind raised shields. Alexander deployed his troops with great skill and earned their devotion by leading them in battle and suffering several wounds.

Alexander visited the fabled city of Troy as he crossed the Bosporus into Asia Minor and routed the Persian forces there. Greek cities in Asia Minor that had been under Persian control welcomed his rule. At the Gulf of Issus in 333 B.C., Alexander soundly defeated Persian emperor Darius III, who retreated so hastily, he left behind family members to be taken hostage.

Refusing to make peace unless Darius yielded to him as emperor, Alexander swept south along the sea toward Egypt. He seized strategic ports, including the defiant Phoenician port of Tyre. He met with more reverence in Egypt, where he was honored as a god-king like the pharaohs of old—veneration he considered his due.

From the Mediterranean, Alexander advanced east into Mesopotamia and engaged Darius’s replenished troops on the plain of Gaugamela in 331 B.C. Once again, Alexander demonstrated that a small army acting in concert was superior to a sprawling, disorganized one. When a gap opened in the Persian ranks, he and his elite cavalrymen dashed into the breach, splitting the opposing army in two. He had conquered the Persians at last.

Pride goeth before the fall

By adding the vast Persian realm to his Balkan kingdom, Alexander forged a Eurasian empire of unprecedented scope. Yet that wasn’t enough. He didn’t heed the Greek lesson about the danger of hubris, striving arrogantly for more than any man could realistically achieve. He subdued Bactria (in modern-day Afghanistan) and wed Roxana, the daughter of a Bactrian chief. He then invaded India in 327 B.C. and crossed the Indus River, the farthest frontier of the old Persian Empire. But monsoons made his troops feverish and mutinous; in 325 B.C., they turned back.

Alexander’s genius was military, not political or diplomatic. He made fitful efforts to organize his huge empire in the style of the Persians; he hired Persian officials and wed Persian princesses (as did dozens of his commanders). Many Macedonians felt he placed too much trust in people they still viewed as enemies, and Greeks consented only reluctantly to his demand to be recognized as divine like some Near Eastern monarchs. “If Alexander wishes to be a god,” Spartans observed skeptically, “let him be a god.”

The mortal Alexander died suddenly (perhaps from typhoid fever) in Babylon in 323 B.C. His empire fractured after his death, but those lands were forever changed, infused with the culture and cosmopolitan spirit of a larger Greek world that Alexander brought into being.

Ancient Greece 101 From artistry to politics, ancient Greece left a considerable impression on world history. Learn why Greek and Roman gods share so many similarities, how the alphabet got its name, and how the legacy of ancient Greece has evolved over thousands of years.
This text is an excerpt from the National Geographic special issue The Most Influential Figures of Ancient History.