Napoleon breakfasted off silver plate at his farmhouse headquarters and dismissed warnings about Wellington with a confidence that may have been partly performance. When his chief of staff suggested recalling Grouchy to concentrate all available forces, Napoleon waved the concern aside. "Wellington is a bad general," he told his officers. "The English are bad troops, and this affair is nothing more than eating breakfast." Whether he believed it or was managing the pessimism of his staff, he pressed on. The ground was sodden after heavy overnight rain, and he delayed his attack to allow it to dry. That delay would cost him the battle.

The battle began on Wellington's right, at the château of Hougoumont, sometime around eleven in the morning. Napoleon's plan called for an initial assault on the buildings to draw Wellington's reserves away from his centre, which would then be struck by a massive infantry attack. It was a sensible idea. What actually happened was something else entirely.

A French brigade surged into the wood and park surrounding Hougoumont and drove out its defenders, but was then thrown back by British artillery fire, losing its commander in the process. A second attack reached the north gate of the château. A French officer called Legros broke the gate open with an axe, and a group of French soldiers forced their way into the courtyard. The Coldstream Guards and Scots Guards rushed to close the gate behind them. The French soldiers trapped inside were killed to the last man. Hougoumont held.

What followed was one of the battle's central ironies. The attack intended to draw Wellington's reserves drew French reserves instead. Napoleon would eventually commit thirty-three battalions, around fourteen thousand troops, to the fight around Hougoumont across the entire afternoon. Wellington matched him, committing twelve thousand of his own troops to keeping the supply lane to the buildings open. He later said that "the success of the battle turned upon closing the gates at Hougoumont." The diversionary attack became the battle within the battle, and it consumed both sides for hours.

While Hougoumont burned, Napoleon's grand battery of eighty guns opened fire on Wellington's centre at around midday. The guns were too far back to aim with real precision, and many of their shot buried in the soft ground, but enough found their marks on the reverse slope to cause serious casualties among the infantry sheltering there. Then, shortly after one in the afternoon, Napoleon launched his main assault: four divisions of infantry from d'Erlon's corps, some fourteen thousand men, advancing in deep columns across a front of roughly a thousand metres toward Wellington's left wing.

The assault was massive and its formations clumsy. The columns were arranged in great rectangular blocks, wide rather than pointed, so that relatively few men could fire at any one time while all were exposed to the fire coming back at them. On the left of the French advance, one division isolated the farmhouse of La Haye Sainte and cut it off from the main British line. The three other divisions climbed the ridge toward Wellington's infantry. At the critical point, they faced a Dutch-Belgian brigade whose skirmishers had been caught in the open while withdrawing, and British brigades under generals Kempt and Pack, who had all suffered badly at Quatre Bras two days before.

The French pushed hard. A gap opened in the Dutch-Belgian line. General Picton, commanding the British and Hanoverian troops in the second line, ordered a counter-attack. Picton was killed almost immediately, shot through the head. His men began to give way under the weight of the French advance. The French 45th regiment burst through a hedge, cheering. Along the sunken road, the British line was dispersing. At two o'clock in the afternoon, Napoleon was winning the Battle of Waterloo.

Then the British heavy cavalry went in. The Earl of Uxbridge, commander of Wellington's cavalry, ordered his two brigades of heavy horsemen to charge from behind the ridge where they had been concealed. The Household Brigade, made up of guards cavalry, swept down the slope and crashed into the French cuirassiers protecting d'Erlon's left flank, scattering them. The Union Brigade, three regiments of heavy dragoons, one English, one Scottish, one Irish, swept through the gaps in the British infantry and struck the French columns from above.

The effect was devastating. The Scots Greys came upon the leading French regiment, the 45th, still reforming after crossing the sunken road, and overwhelmed it, capturing its regimental eagle, the symbolic standard carried by every French unit. The Royal Dragoons destroyed another French brigade and captured a second eagle. These were the only two French eagles taken by the British in the entire battle. D'Erlon's corps, fourteen thousand men, was driven back across the valley in rout, at a cost of three thousand casualties including two thousand prisoners.

But the British cavalry did not stop. Their officers could not rein them in. Blown horses and disordered troopers galloped on past the French infantry and into the guns of the grande battery, putting many of them temporarily out of action. Then Napoleon counter-attacked with his own cavalry: armoured cuirassiers and lancers swept back up the valley. General Ponsonby, commanding the Union Brigade, was captured while trying to rally his men. A nearby group of Scots Greys saw the capture and rode to rescue him. The French lancer who held Ponsonby killed him, then killed three of the Greys as well. The momentum had swung back to France.

The Union Brigade lost heavily. The Scots Greys were practically wiped out as a fighting force. The two heavy brigades, which had entered the charge with around two thousand men, would by the end of the day be able to muster a single combined squadron. They had saved Wellington's left at the critical moment, but at a price that crippled his cavalry for the rest of the afternoon. Wellington, who understood cavalry's tendency to overreach, had warned before the battle that he was reluctant to commit large numbers of horsemen against equal numbers of French, precisely because British cavalry, for all its quality, lacked the discipline to halt a charge once started.

By mid-afternoon, with d'Erlon's corps temporarily shattered and Hougoumont still holding, Marshal Ney made a decision that puzzled observers then and has puzzled historians since. Watching what he took to be signs of retreat in Wellington's centre, movement that was actually the removal of casualties to the rear, he committed the French cavalry to a massive assault on the Anglo-allied ridge. Around forty-eight hundred horsemen went in first, then another wave was added until roughly nine thousand cavalry in sixty-seven squadrons were charging up the slope in successive waves.

Wellington's infantry responded by forming squares, hollow box formations four ranks deep, each side bristling with bayonets. Cavalry horses would not charge home against a solid wall of steel. The squares were smaller than paintings of the battle suggest: a battalion of five hundred men would form a square perhaps eighteen metres on a side. They were vulnerable to artillery, which could blow gaps in the formation through which cavalry could pour, but at Waterloo the French cavalry and artillery failed to co-ordinate. The guns did not move close enough to the Anglo-allied line in sufficient numbers to be decisive.

Wave after wave of French horsemen swept up the slope, swirled around the infantry squares, and fell back under artillery fire from Wellington's gunners, who had been ordered to shelter inside the squares as the cavalry approached and then race back to their guns as the cavalry withdrew. At least one artillery officer, Captain Mercer commanding a battery of nine-pounders, disobeyed the order and kept his guns firing throughout, judging that the Brunswick troops on either side of him were too unsteady to survive without the moral support of his guns in action. His account of watching the leading French rank collapse under his fire is one of the most vivid eyewitness passages of the entire battle.

After numerous assaults, the French cavalry was spent. Four divisional commanders had been wounded, nine brigadiers wounded, one killed. Guyot's Guard heavy cavalry division had lost nearly half its strength. The squares had held. But the cost to Wellington's infantry of simply standing in formation under artillery fire between charges had been enormous. The men were exhausted, battered, and some units were running dangerously short of ammunition.

The crisis came when La Haye Sainte finally fell. The King's German Legion garrison had held the farmhouse through most of the day against repeated French assaults, but late in the afternoon their ammunition ran out. The French took the building. With La Haye Sainte in French hands, Ney pushed skirmishers and horse artillery forward to within sixty yards of Wellington's centre and began to blast the infantry squares at close range with canister shot.

The results were catastrophic. Two British regiments, the 30th and 73rd Foot, took such losses they had to merge into a single square to remain viable. The 27th Foot, the Inniskillings, was hit so badly by French sharpshooters firing from a nearby knoll that it lost two thirds of its strength while unable to leave its square formation. Wellington's generals and aides were falling around him: his military secretary was wounded, his quartermaster-general mortally so, two divisional commanders hit. Wellington himself rode into a square to escape French skirmishers who had appeared around La Haye Sainte and fired on his staff. Trapped inside, ignorant of events beyond the square, he later wrote that the time waiting for Prussian help "seemed interminable. Both they and my watch seemed to have stuck fast."

Ney sent word to Napoleon requesting fresh infantry to exploit the breakthrough. Napoleon refused. He had no fresh infantry to spare. The moment passed. Wellington's line, battered almost beyond endurance, held on by force of will and the simple fact that the Prussians were now arriving.

The Prussian march to Waterloo had been a nightmare of delay. The roads were churned to mud by the overnight rain. A fire broke out in the town of Wavre and blocked the streets through which Bülow's corps had to pass. Moving eighty-eight artillery pieces through the congestion took hours. The leading Prussian elements had set off at four in the morning; the last did not leave until ten, six hours later. Napoleon, when he first spotted Prussian columns arriving at around quarter past one in the afternoon, had declared they would need two days to recover from Ligny and would be dealt with by Grouchy. He was wrong on both counts.

Grouchy, with thirty-three thousand French troops, was at that moment fighting the Prussian rearguard at Wavre, twenty kilometres away, pinned in place by the River Dyle and unable to reach Waterloo. The orders Napoleon sent him during the battle arrived after nine in the evening, far too late to matter. Those thirty-three thousand French soldiers played no part in the decisive battle of the campaign.

Bülow's Prussian corps struck the French right flank at around half past four in the afternoon, driving for the village of Plancenoit in the French rear, directly threatening Napoleon's only line of retreat. Napoleon sent first his Young Guard, then two battalions of his elite Old Guard infantry into Plancenoit to stabilise the position. The fighting in the village was savage: house to house, graveyard to graveyard, the church itself on fire. Plancenoit changed hands five times before the day was done. But the Prussians kept coming, and they were not alone: Zieten's corps was arriving on Wellington's left flank, allowing Wellington to shift cavalry from his left to his crumbling centre.

The French had been expecting Grouchy's army to appear from the direction of Wavre. When Prussian troops appeared there instead, the shock, as one account puts it, "shattered French morale." The sight of Prussian blue where French reinforcements should have been spread turmoil through Napoleon's army. D'Erlon's corps, reforming after the afternoon's disasters, broke and fled in panic. And still Napoleon had one card left to play.

At around half past seven in the evening, with Wellington's centre exposed by the fall of La Haye Sainte and the Plancenoit front temporarily stabilised by the Guard battalions sent there, Napoleon committed his final reserve: the Middle Guard infantry, five battalions of the most experienced soldiers in France, units that had never been broken in battle. Behind them, in reserve, stood three battalions of the Old Guard. This was everything. There was nothing left after this.

Marshal Ney led the advance, mounted on his fifth horse of the day, the previous four having been killed under him. Napoleon oversaw the initial deployment, then left Ney to conduct the assault. The Middle Guard moved up the ridge in battalion squares, each around five hundred and fifty men, with artillery sections between them. Other French troops advanced in support on both flanks: cavalry and infantry from Reille's corps on the left, rallied elements of d'Erlon's corps on the right. French artillery moved forward and began hammering the Anglo-allied line. Several British brigades began to give way. The Prince of Orange led a counter-attack and was seriously wounded. The situation for Wellington was as close to breaking point as it had been all day.

Then the Guard crested the ridge and found it apparently empty, covered with dead. What happened next was one of the decisive moments of the entire Napoleonic era. Fifteen hundred British Foot Guards, who had been lying flat to shelter from the French artillery, rose to their feet at close range and fired a devastating volley into the advancing French chasseurs. Around three hundred men fell from that single discharge, including two battalion commanders. A bayonet charge by the Foot Guards broke the leaderless squares.

Further along the line, a Dutch division under General Chassé had held back, relatively fresh. Chassé ordered his artillery forward and then sent his infantry in with the bayonet. The French grenadiers faltered and broke. The 4th Grenadiers, seeing their comrades retreat, wheeled about and retired. Then, on the flank of the surviving French chasseurs, a British light infantry regiment wheeled in line and poured a devastating fire into them. The chasseurs broke. The Guard was retreating.

The words passed through the French army like a shockwave. "La Garde recule. Sauve qui peut." Wellington stood up in his saddle and waved his hat forward. His entire army, exhausted and battered as it was, surged off the ridge toward the fleeing French. The battle was over. What remained was the pursuit.

A last stand was attempted south of La Haye Sainte, where surviving Imperial Guard battalions tried to cover the retreat. Adam's brigade and relatively fresh cavalry under Vivian and Vandeleur threw them into confusion. The famous cry attributed to a Guard officer, "La Garde meurt, elle ne se rend pas," the Guard dies, it does not surrender, may be apocryphal, but it captured something true about those last minutes: the Guard fought until it could not.

At Plancenoit, the Prussian pressure finally broke through completely. The church was on fire, its graveyard strewn with bodies. The Young Guard Division reported ninety-six per cent casualties. Two thirds of the French corps that had been holding the flank ceased to exist. The Old Guard battalions that had stabilised Plancenoit earlier retreated in good order until they met the mass of panicking troops streaming away from the main battlefield, and were swallowed into the rout.

Coalition cavalry pursued the fleeing French army until around eleven at night. Near the town of Genappe, Prussian cavalry captured Napoleon's abandoned carriage, still containing an annotated copy of Machiavelli's "The Prince" and a cache of diamonds left behind in the rush to escape. Those diamonds became part of the Prussian crown jewels. At around nine in the evening, in the darkness near the inn of La Belle Alliance, Wellington and Blücher met on horseback and saluted each other as victors.

The cost was staggering. Wellington lost around seventeen thousand men killed or wounded. Blücher lost around seven thousand, with eight hundred and ten of those casualties belonging to a single regiment that had fought at both Frichermont and Plancenoit. Napoleon's losses were somewhere between twenty-four and twenty-six thousand killed or wounded, with six to seven thousand taken prisoner, and another fifteen thousand who deserted in the days that followed. A visitor who toured the field on 22 June, four days after the battle, wrote that the sight was "too horrible to behold," that he "felt sick in the stomach and was obliged to return," confronted by heaps of wounded men with mangled limbs, unable to move, perishing without treatment.

The bodies of tens of thousands of men were buried hastily in mass graves across the field, a process that took at least ten days. Almost none of those graves have ever been found. A likely reason is grimly practical: in the years after the battle, local farmers dug up the bones of men and horses and sold them to a nearby sugar factory, where they were ground down and burned to make bone-char, used to filter sugar syrup. The soldiers of Waterloo were literally consumed by the economy of the country they had fought over.

The teeth were another matter. Tens of thousands of teeth were pulled from the mouths of dead soldiers by scavengers, including some who had travelled from Britain specifically for the purpose. They were in demand because they came from young, healthy men. For decades afterward, dentures across Europe were fitted with what the trade called Waterloo teeth.

Napoleon fled to Paris, arriving in the early hours of 21 June. He believed briefly that he could raise another army, rally French opinion, and fight on. He was wrong. The Chamber of Deputies voted to make itself permanent rather than allow him to dissolve it. General Ney, who had led charge after charge at Waterloo, told the legislature that Paris would fall if Napoleon remained in power. On 22 June Napoleon tried to abdicate in favour of his son; the legislature rejected it. Two days later, on 24 June 1815, he announced his second and final abdication as Emperor of the French.

He tried to escape to North America, but the Royal Navy was blockading French ports. On 15 July he surrendered to the captain of a British warship, the Bellerophon, writing to the Prince Regent a letter that compared himself to the Athenian general Themistocles, throwing himself upon the hospitality of his most powerful enemy. He was exiled to the remote South Atlantic island of Saint Helena. He died there in 1821, and never returned to France.

Wellington, reflecting on the battle, called it "the nearest-run thing you ever saw in your life." That assessment has shaped how historians have approached it ever since: as a contingent event, one that could have gone differently at a dozen points. If the Prussians had retreated east instead of north after Ligny, they would never have reached Waterloo in time. If Grouchy had marched toward the guns rather than following his orders to Wavre, he might have intercepted Bülow's corps. If the British heavy cavalry had held their charge at the valley floor, Wellington would have had a viable reserve for the afternoon. If Napoleon had attacked in the morning before the ground dried, he might have broken Wellington's line before the Prussians arrived.

But none of those things happened, and the consequences were immediate and lasting. Napoleon abdicated four days after the battle. Coalition forces entered Paris on 7 July. Louis the Eighteenth was restored to the French throne. The Treaty of Paris was signed in November 1815. The wars that had consumed Europe since the French Revolution of the early 1790s, more than twenty years of near-continuous conflict, were over.

The generation that followed looked back at Waterloo as the hinge point of modern European history. It ushered in what became known as the Concert of Europe, a system of great-power diplomacy that, for all its flaws, kept the continent from another general war for nearly four decades, until the Crimea in 1853. The phrase "meeting one's Waterloo" entered the English language as a shorthand for a catastrophic and final reversal. Monuments went up across the continent: a column in Hanover, an obelisk in Scotland, the Lion's Mound in Belgium, a vast artificial hill built from earth taken from Wellington's own ridge, which so altered the battlefield that Wellington, visiting two years later, reportedly exclaimed that they had changed his field of battle.

The British Foot Guards who broke the Middle Guard were mistakenly credited with defeating the Grenadiers of the Old Guard, the most elite infantry in France. As a reward, they were renamed the Grenadier Guards and adopted the tall bearskin caps of the men they had supposedly beaten. Britain's Household Cavalry adopted the steel breastplate in 1821, in honour of their charge against the French cuirassiers. The effectiveness of the lance, demonstrated so brutally in the killing of Ponsonby, led Britain to convert its first cavalry regiment to lancers the following year. Waterloo reshaped not just the map of Europe but the look of armies, the grammar of military honour, and the language of defeat.

What it left on the ground at Mont-Saint-Jean was simpler and harder. A ridge. A farmhouse gate that was forced open and then slammed shut. A churchyard in Plancenoit where the dead lay as if scattered by a whirlwind. And somewhere beneath the fields that local farmers ploughed in the years that followed, the bones of tens of thousands of men from a dozen nations, ground down and burned, filtered through sugar, and dissolved into the ordinary commerce of a continent trying to forget what it had done to itself.