The Battle of Waterloo, fought near the village of Waterloo on Sunday 18 June 1815, 1815 Calendar was the decisive battle of the Waterloo Campaign, and Napoleon Bonaparte"s last. Waterloo marked the end of the period known as the Hundred Days, which began in March 1815 after Napoleon"s return from Elba, where he had been exiled after his defeat and abdication in the previous year. The defeat at Waterloo put a final end to Napoleon"s rule as Emperor of the French.

After Napoleon returned to power in 1815, many states which had previously resisted his rule formed the Seventh Coalition and began to mobilise armies to oppose him. The first two assembled close to the northeastern border of France. They consisted of a Prussian army under the command of Gebhard von Blücher, and an Anglo-Allied army under the command of the Duke of Wellington. Napoleon chose to attack in the hope of destroying them before they, with other members of the Seventh Coalition, could join in a coordinated invasion of France.

The campaign consisted of four major battles: Quatre Bras (16 June), Ligny (16 June), Waterloo (18 June), and Wavre (18 June – 19 June). According to the Duke of Wellington, the battle at Waterloo was "the nearest-run thing you ever saw in your life."Wellington citing Creevey Papers, ch. x, p. 236

It rained heavily overnight on 17 June, so Napoleon delayed giving battle until noon on 18 June to allow the ground to dry. Wellington"s army, positioned across the Brussels road on the Mont St Jean escarpment, withstood repeated attacks by the French, until, in the evening, the Prussians arrived in force and broke through Napoleon"s right flank. At that moment, the British counter-attacked and drove the French army in disorder from the field. Pursuing Coalition forces entered France and restored Louis XVIII to the French throne. Napoleon abdicated, surrendering to the British, and was exiled to Saint Helena, where he died in 1821.

The battlefield is in present-day Belgium, about eight miles (12 km) SSE of Brussels, and about a mile (2 km) from the town of Waterloo. The site of the battlefield is today dominated by a large mound of earth, the Lion"s Hillock. As this mound used earth from the battlefield itself, the original topography has not been preserved.