Waterloo, Battle of, June 18, 1815, the final battle of the Napoleonic Wars and one of the most important battles in history. It took place near the village of Waterloo, a short distance south of Brussels, Belgium. With the entire future of Europe at stake, both sides fought with desperate bravery. Napoleon was decisively defeated.

Early in 1815, Napoleon had escaped to France from his exile on the island of Elba. Leaders of the allied powers of Europe, then meeting at the Congress of Vienna, agreed to crush France. They began to mass hundreds of thousands of troops on its borders. Napoleon decided to strike before his enemies reached full strength. Quickly he moved 125,000 troops to the Belgian border. A few miles away were 90,000 British, Dutch, Belgians, and Germans under the Duke of Wellington and 115,000 Prussians under Marshal Blücher. Napoleon planned to surprise the two armies, drive between them, and defeat each one separately.

At first, Napoleon was partly successful. On June 16 he defeated the Prussians at Ligny and forced Blücher to fall back. The victory was not complete, however, because Marshal Ney, whose help was needed to destroy the Prussians, mismanaged a preliminary attack on British forces at Quatre Bras and arrived too late. On June 18 Napoleon turned on Wellington, while Marshal Grouchy, at the head of 33,000 French troops, hunted for Blücher. Wellington's regiments, regrouped a few miles south of Waterloo, withstood the fierce assaults and threw back Marshal Ney and the French cavalry. France's Old Guard, held in reserve, staked their lives in a terrific charge on Wellington's central line, but lost.

Grouchy was signaled to return, but he was unable to do so. Blücher's Prussians arrived on the battlefield at nightfall and Wellington ordered a general charge, ending the battle. Killed, wounded, or reported missing were 33,000 Frenchmen and 23,000 of the allies.

Napoleon galloped off to Paris with a few companions. The gathering odds were too great for him; France was weak and worn out. Four days later, he abdicated. He was exiled to the island of St. Helena, and the Congress of Vienna resumed its work.