For as long as human civilization has existed, so has war. Often a deciding factor in the history of centuries to come, decisive battles are among the most crucial chapters of the human story. The most important of those chapters are the biggest losses. The worst defeats in history shattered nations and broke empires. They signaled the end of eras and the rise of new ways of thinking. In essence, they completely reset the drawing board for humanity.
These defeats have much to teach us. Studying how a battle is lost is often more useful than analyzing how it was won. It shows how history went wrong, and how to avoid such a fate in the future.
The Battle of Cannae was fought between the forces of Rome and Carthage, the latter led by Hannibal. Hoping for a decisive victory over Hannibal, Rome sent a massive force after the Carthaginian army. Outnumbered, Hannibal drew the Romans in with a retreating line of men, before flanking them with spearmen. A cavalry charge from the rear surrounded the Romans, and the army of Carthage devastated them.
The Battle of Cannae is known as the greatest defeat in Roman history, and one of the great strategic coups in history. As many as 70,000 Roman soldiers were lost in the battle.
When Persians, under King Darius I, invaded Greece, Athenians had little time to react. Athenian commander Militiades assembled an army as quickly as possible and positioned it so that marshes and mountains blocked Persian cavalry, robbing the enemy of a major advantage. The Greeks then charged with a thin center, using strengthened flanks to break through Persian ranks.
Though the Greek center was weak, it held just long enough for the plan to work. The bravery and endurance of the soldiers at the center, known as Marathon Men, became legendary in Greece, as did the tale of their messenger running 25 miles to Athens to relay news. This gave rise to the tradition of running marathons.
After Persian King Xerxes I defeated the Spartans at Thermopylae, the Greeks blocked the advance of Xerxes' naval forces with a fleet less than half the size of that of the Persians. They then lured the Persians into a narrow passage, where the large Persian ships couldn't maneuver well. The Greeks destroyed enough of Xerxes' fleet to seriously compromise his invasion plans. In addition to being a monumental loss in the expansion of the Persian Empire, the Battle of Salamis was one of the most important naval battles in recorded history.
Known as one of the worst defeats in Roman history, the Battle of Teutoburg Forest was waged between the Germanic forces of nobleman Arminius and three legions of Rome. The unsuspecting Romans were ambushed by the Germanic force, which hid among trees in the dense forest. The Germans surrounded the Romans and stormed them.
Arminius received a Roman military education in his youth, and was able to use Roman strategy against the Legions. Publius Quinctilius Varus, commander of Rome's men, ended his life in the wake of the battle.