In 218 BCE, a Carthaginian general decided to invade Italy by walking through the Alps. He brought approximately fifty thousand soldiers, nine thousand cavalry, and thirty-seven war elephants. The Romans thought the mountains were impassable. Hannibal Barca had not been informed. The crossing killed roughly half his army. Most of the elephants died. The ones that survived arrived in northern Italy with a force that was smaller, exhausted, and freezing. Hannibal then proceeded to destroy every Roman army sent against him for the next fifteen years.

He Beat Rome by Thinking Like No One Had Thought Before

Hannibal did not fight the way generals were supposed to fight. At the Battle of Trebia, he hid cavalry behind the Roman lines and attacked from behind while the legions were engaged at the front. At Lake Trasimene, he concealed his entire army in the fog along a lakeshore and ambushed a Roman column so completely that the Roman consul died in the first minutes and his entire force was killed or captured. Then came Cannae. Military historians at the United States Military Academy at West Point still teach Cannae as the most perfect tactical battle in the history of warfare. Hannibal placed his weakest troops in the center and let the Romans push them back, creating a crescent that slowly enclosed the Roman army on three sides. The cavalry closed the fourth. Roughly seventy thousand Romans were killed in a single afternoon. It was the bloodiest day in European military history until the Battle of the Somme in 1916. After Cannae, Rome should have surrendered. Every military calculation said they should surrender. They had lost three armies in two years. Their best generals were dead. Hannibal was standing in their countryside. They refused.

Rome Won by Refusing to Lose

This is the part of the story that is hardest to explain and most important to understand. Hannibal won every major battle in Italy for fifteen years. He never lost a significant engagement on Italian soil. And he lost the war. Scholars of Punic War strategy at the University of Oxford have argued that Hannibal's fundamental problem was strategic, not tactical. He could destroy armies but he could not destroy Rome. The city was too large, too well fortified, and too stubborn to collapse under military pressure alone. He needed Rome's allies to defect. Some did. Most did not. The Roman system of alliances, built over centuries, held. Meanwhile, Rome did something that Hannibal could not match: they kept producing armies. Every army he destroyed was replaced by another one. Every general he killed was replaced by another general. The Romans lost battle after battle and treated each loss as a training exercise. Eventually, a Roman general named Scipio took the war to Africa, threatening Carthage itself. Hannibal was recalled from Italy to defend his homeland. At the Battle of Zama in 202 BCE, he was defeated for the first and only time. Carthage surrendered. He had spent fifteen years in his enemy's country, undefeated in battle, and it was not enough. The man who walked elephants across mountains discovered that some walls cannot be climbed.