On June 15, 1815, perhaps the most famous (or infamous) ball in history was held. The Duchess of Richmond’s ball is generally regarded as the event in which Arthur Wellesley, Duke of Wellington, was informed of the advance of French forces into the kingdom of the Netherlands. This is somewhat accurate.

In March of 1815, Napoleon Bonaparte escaped Elba and landed in France, quickly assuming control of the Empire of France from Louis XVIII, setting off the Hundred Days campaign. The nations of Europe, quickly mobilized against him, with the British and the Prussians fielding armies in the Netherlands, while the Russians, Austrians, and several Germanic Princedoms marched to support them. Thus, outnumbered and facing enemies on potentially three sides, Napoleon knew his only chance was to defeat the coalition armies separately before they could assemble against him.

The allies had set the date of their invasion of France for July 1, but it was considered possible (perhaps even likely, given the reputation of the French Emperor) the French would attack first. The Duchess of Richmond, whose husband was the commander of British forces defending Brussels, had planned some weeks earlier to host a ball. When rumors of French advances began to run through the city, she asked Wellington if the ball should be canceled his response was: “Duchess, you may give your ball with the greatest safety, without fear of interruption.” Thus, the ball was held as scheduled, the most likely location being a coach house attached to the house the Lennox family was leasing in Brussels.

When the first circles of Brussels society gathered that night, the main topic of discussion was, of course, the rumored impending invasion. Even with so desperate a subject on the tongues of those who attended, however, by all accounts the ball proceeded smoothly. Wellington and his commanders arrived at about 11 PM that evening, and it was said that “with the exception of three generals, every officer high in [Wellington’s] army was there to be seen.”

But Wellington had allowed the ball to go on that evening in an attempt to confirm that all was well and proceeding as planned. In reality, he had received word earlier that day that the French army had crossed the Belgian frontier and was engaging the British allies, the Prussian army, to the east. Wellington put the entire British army on alert. But he was still unaware of the speed of the French advance and the location of the attack and did not order his army to mass just yet.

Just before dinner, a dispatch arrived for William, Prince of Orange, commander of the Dutch-Belgian army. The prince handed Wellington the missive, who put it in his pocket and continued on as if nothing had happened. When he read the note twenty minutes later, he ordered William back to his command post and went into supper. To his surprise, William returned only a short time later with word that the French had pushed much further than expected.

By now rumors were flying through the ballroom. Wellington orders both William and the Duke or Brunswick back to their command posts, though he, himself stayed for another twenty minutes. Then he announced his intention to retire. Before he left the room, however, he whispered in Duke of Richmond’s ear, asking if he had a good map. The two men left the room, going to Richmond’s study, where Wellington surveyed the potential battlefields. The French had pushed far enough into the Belgian countryside that they now threatened Quatre Bras, and Wellington, knowing he would not be able to mobilize his army in time to stop them there, exclaimed: “Napoleon has humbugged me, by God; he has gained twenty-four hours’ march on me.” As he surveyed the map, he fixed his gaze on Waterloo and allowed his finger to fall in the name as the place where the British would stop the French.

By now the ball was all but over. Officers were pulled from the ballroom and given orders to return to their units, and many did so without even changing back into their uniforms, fighting in their suits and dancing shoes. Those who bade them farewell weeping with fear for those who were going into danger, knowing not all of them would return. The city soon became a bustle of movement as the regiments departed for the front and the battle against the invading French.

The next day, both the Battle of Quatre Bras and the Battle of Liege were fought. Quatre Bras was a victory for the British as they denied Napoleon the crossroads and his strategic objective of driving a wedge between the two allied armies. Liege was a victory for Napoleon, but he was not able to destroy the Prussians. The British, by Wellington’s design, fell back to Waterloo and linked up with the Prussian army. Two days later, the final battle of the Napoleonic wars was fought at Waterloo, and the French were defeated, ending Napoleon’s power forever.