But Napoleon had thrown aside all thought of a merely defensive war. By amazing efforts he had raised an army of two hundred and fifty thousand men in the few months since his arrival in Paris; and in the opening of June one hundred and twenty thousand Frenchmen were concentrated on the Sambre at Charleroi, while Wellington's troops still lay in cantonments on the line of the Scheldt from Ath to Nivelle, and Blucher's on that of the Meuse from Nivelle to Liege. Both the allied armies hastened to unite at Quatre Bras; but their junction was already impossible. Blucher with eighty thousand men was himself attacked by Napoleon at Ligny, and after a desperate contest driven back with terrible loss upon Wavre. On the same day Ney with twenty thousand men, and an equal force under D'Erlon in reserve, appeared before Quatre Bras, where as yet only ten thousand English and the same force of Belgian troops had been able to assemble. The Belgians broke before the charges of the French horse; but the dogged resistance of the English infantry gave time for Wellington to bring up corps after corps, till at the close of the day Ney saw himself heavily outnumbered, and withdrew baffled from the field.
About five thousand men had fallen on either side in this fierce engagement: but heavy as was Wellington's loss, the firmness of the English army had already done much to foil Napoleon's effort at breaking through the line of the Allies. Blucher's retreat however left the English flank uncovered; and on the following day, while the Prussians were falling back on Wavre, Wellington with nearly seventy thousand men - for his army was now well in hand - withdrew in good order upon Waterloo, followed by the mass of the French forces under the Emperor himself. Napoleon had detached Marshal Grouchy with thirty thousand men to hang upon the rear of the beaten Prussians, while with a force of eighty thousand he resolved to bring Wellington to battle. On the morning of the 18th of June the two armies faced one another on the field of Waterloo in front of the Forest of Soignies, on the high road to Brussels. Napoleon's one fear had been that of a continued retreat. "I have them!" he cried, as he saw the English line drawn up on a low rise of ground which stretched across the high road from the chateau of Hougomont on its right to the farm and straggling village of La Haye Sainte on its left. He had some grounds for his confidence of success.
On either side the forces numbered between seventy and eighty thousand men: but the French were superior in guns and cavalry, and a large part of Wellington's force consisted of Belgian levies who broke and fled at the outset of the fight. A fierce attack upon Hougomont opened the battle at eleven; but it was not till midday that the corps of D'Erlon advanced upon the centre near La Haye Sainte, which from that time bore the main brunt of the struggle. Never has greater courage, whether of attack or endurance, been shown on any field than was shown by both combatants at Waterloo. The columns of D'Erlon, repulsed by the English foot, were hurled back in disorder by a charge of the Scots Greys; but the victorious horsemen were crushed in their turn by the French cuirassiers, and the mass of the French cavalry, twelve thousand strong, flung itself in charge after charge on the English front, carrying the English guns and sweeping with desperate bravery round the unbroken squares whose fire thinned their ranks. With almost equal bravery the French columns of the centre again advanced, wrested at last the farm of La Haye Saintefrom their opponents,and pushed on vigorously though in vain under Ney against the troops in its rear.
But meanwhile every hour was telling against Napoleon. To win the battle he must crush the English army before Blucher joined it; and the English army was still uncrushed. Terrible as was his loss, and many of his regiments were reduced to a mere handful of men, Wellington stubbornly held his ground while the Prussians, advancing from Wavre through deep and miry forest roads, were slowly gathering to his support, disregarding the attack on their rear by which Grouchy strove to hold them back from the field. At half-past four their advanced guard deployed at last from the woods; but the main body was far behind, and Napoleon was still able to hold his ground against them till their increasing masses forced him to stake all on a desperate effort against the English front. The Imperial Guard - his only reserve, and which had as yet taken no part in the battle - was drawn up at seven in two huge columns of attack. The first, with Ney himself at its head, swept all before it as it mounted the rise beside La Haye Sainte, on which the thin English line still held its ground, and all but touched the English front when its mass, torn by the terrible fire of musketry with which it was received, gave way before a charge.
The second, three thousand strong, advanced with the same courage over the slope near Hougomont, only to be repulsed and shattered in its turn. At the moment when these masses fell slowly and doggedly back down the fatal rise, the Prussians pushed forward on Napoleon's right, their guns swept the road to Charleroi, and Wellington seized the moment for a general advance. From that hour all was lost. Only the Guard stood firm in the wreck of the French army; and though darkness and exhaustion checked the English in their pursuit of the broken troops as they hurried from the field, the Prussian horse continued the chase through the night. Only forty thousand Frenchmen with some thirty guns recrossed the Sambre, while Napoleon himself fled hurriedly to Paris. His second abdication was followed by the triumphant entry of the English and Prussian armies into the French capital; and the long war ended with his exile to St. Helena, and the return of Lewis the Eighteenth to the throne of the Bourbons.