Waterloo, battle of, 1815. In June 1815, Napoleon struck into Belgium, hoping to destroy Wellington's Anglo-Dutch army and Blücher's Prussians before they could unite. After the battle of Quatre Bras on 16 June, Wellington's inexperienced army of 67,000 men (of whom less than a third were British) fell back to a ridge near Waterloo. The 89,000 strong Prussian army, badly mauled at Ligny on the same day, also retreated. The French Marshal Grouchy pursued Blücher with 33,000 men, fighting an action at Wavre on 18 June, but failed to prevent the Prussians from marching to Wellington's aid.

The battle began on 18 June with an unsuccessful attack on Hougoumont, a fortified farmhouse on Wellington's right flank. A major attack developed in the centre, but the French infantry were driven back. Then for about 90 minutes the French made a series of fruitless attacks with unsupported cavalry on unbroken allied infantry squares. The arrival of Prussian forces compelled Napoleon to send part of his élite Imperial Guard to his right flank. By 6.30 p.m. the key farmhouse of La Haye Sainte had fallen to the French, and an all-out assault might have broken Wellington's lines. However, Napoleon prevaricated, and only released his reserve—the Imperial Guard—at 7.00. The repulse of the Guard was the signal for the rout of Napoleon's army. With Blücher's men pouring on the field, Napoleon was finally defeated.

Gary Sheffield

Waterloo, Battle of (June 18, 1815) Final engagement of the Napoleonic Wars, fought c.20km (12mi) from Brussels, Belgium. The Duke of Wellington commanded Allied troops against Napoleon I's slightly larger French forces. The conflict was stalemated until the Prussians, under Marshal Blücher, arrived to overwhelm the French flank, whereupon Wellington broke through the centre. The battle ended Napoleon's Hundred Days and resulted in his second and final abdication.

Waterloo, Battle of a battle fought on 18 June 1815 near the village of Waterloo (in what is now Belgium), in which Napoleon's army was conclusively defeated by the British (under the Duke of Wellington) and Prussians. Waterloo is often used as a word for a decisive defeat or failure.
Waterloo ball a frivolous entertainment preceding a serious occurrence (with reference to a ball given in Brussels by the Duchess of Richmond on the eve of the Battle of Waterloo).