Yet, if the square was steady and shot at the right time, it should not happen. Each side of a square was formed of four ranks. The two front ranks knelt, their bayonet-tipped muskets driven hard into the ground to make a hedge of steel. The two ranks behind stood with muskets levelled. Once the front two ranks had fired, they did not reload but just held their bayonets hard and steady. The rear ranks could load and fire, load and fire, and the attacking horses, unwilling to charge such an obstacle, would swerve away from the face of the square to be raked by the fire of the square’s flanks.

Yet one dead horse, slithering in mud and blood, could break that theory. And when one square broke its men would run for shelter to another square, fighting their way inside, and the horsemen would ride with them, letting the panicked infantry break the second square’s ranks apart. Then the butchery could continue.

“The daft bugger misjudged!” Harper said with undisguised glee.

The French cavalry commander had formed his attack into a succession of long lines, but too long, for the flanks were approaching the fields of fire from Hougoumont and La Haye Sainte. Those bulwarks that lay like breakwaters ahead of the British line were being besieged by infantry, but their defenders had muskets and rifles enough to fire on the tempting target of the cavalry which was thus forced to contract its line. The wings of the cavalry trotted inwards, thickening the centre of the attack, but also compressing it so that as the horsemen began to climb the British ridge they looked more like a column of horsemen than a charging line. The compression became worse as the horsemen neared the crest and squeezed yet further inwards from the threat of the flanking batteries. The horses were so tightly packed that some were lifted clean off the muddy ground and carried along by their neighbours. The air was filled with the chink of curb chains, the slap of scabbards on leather, the thump of hooves, and the whipping sound of lance pennants napping.

The British cannons drowned the cavalry’s noise. The first volley came from the nine-pounder batteries on the ridge’s crest. The guns smashed roundshot deep into the compressed formation. The second volley was double shotted and Sharpe, in the deafening echo of the guns’ reports, heard the clatter of the musket-balls striking the Cuirassiers’ breastplates. The gunners reloaded frantically, ramming a last charge of canister down the hot barrels as the French trumpets threw the attack into a canter.

“Fire!” A last volley was fired from the threatened guns. Sharpe had a tangled impression of horsemen flailing inwards from the canisters’ strike, then he and Harper turned their horses and raced for the safety of the nearest square. Staff officers who had been positioned on the crest were similarly galloping to safety,

Sharpe and Harper thudded through an opening in a square of Guardsmen that immediately closed ranks behind the two Riflemen. Thirty yards in front of the square a battery of horse artillery waited for the enemy.

The French horsemen were close, but still hidden by the fall of the forward slope, and there followed one of the odd moments of apparent battlefield silence. The French gunners, fearful of hitting their own cavalry, had ceased fire, while the closest British gunners had yet to be given their target. It was not a true silence, for the enemy infantry still snarled and fired around Hougoumont and La Haye Sainte, and the guns in the eastern part of the valley still fired, while closer, much closer, there was the thunderous shaking of uncountable hooves, yet the absence of the murderous enemy bombardment made the moment seem very like silence. There was even a palpable relief that the shells and round-shot had stopped their slaughter. Men drew breath as thqy waited and watched the empty crest which was topped with dirty smoke.

Somewhere beyond the smoke a trumpet screamed.

“Hold your fire when you first see Monsewer!” A mounted Guards major walked his horse behind the face of the square where Sharpe and Harper had taken refuge. “Let the bastards get close enough to smell your farts before you kill them! Take that smile off your face, Guardsman Proctor. You’re not here to enjoy yourself, but to die for your King, for your country, and above all for me!”

Harper, liking the Guards officer’s style, grinned as broadly as any of the Guardsmen. The Major winked at Sharpe, then continued his harangue. “Don’t waste your powder! And remember you are Guardsmen, which is almost like being gentlemen, so you will behave with good manners! Permit the little darlings to lift their skirts before you give them your balls!”

And suddenly the little darlings were there as the ridge filled with a horde of horses. One moment the skyline was empty, then the world was dominated by cavalry and the sky was pierced by the last fine notes which hurled the Cuirassiers into their gallop.

The close support artillery, exposed in the spaces between the squares, opened fire. The guns slammed back on their trails, spewing mud from their bucking wheels.

Sharpe saw a cannon-ball split the mass of horsemen apart as though an invisible cleaver had chopped through the formation. The gunners were clearing the gun’s barrel, ramming a canister onto a powder charge, and hurling themselves away from the coming recoil.

“Fire!” This time a blast of canister flailed a dozen tight-packed horses to the ground, then the artillerymen were abandoning their cannon to seek safety inside the squares. The gunners carried their rammers and portfires with them.

The Cuirassiers could not be stopped by cannon-fire. They flowed round their dead and dying and threw themselves at the squares in a desperate, brave charge. They had believed themselves to be pursuing a broken and fleeing enemy, and their General had promised that the only obstacles between them and the whores of Brussels were a few demoralized Goddamn fugitives, yet now the horsemen discovered they had ridden to a bitter trap. The squares had been hidden behind the crest, the enemy was not broken and running, but instead standing and waiting to fight.

Yet these were the Emperor’s Cuirassiers, his ‘big brothers’, and glory would be theirs if they broke these squares. High above each British battalion hung the colours that, if captured, would give a man eternal fame in an empire’s heaven, and so the horsemen screamed a challenge and lowered the points of their heavy swords.

“Number One and Two Companies!” The Guards Major eschewed his jesting as the enemy came close. “Wait for my word!” He paused. Sharpe could hear the horses’ breathing, see the distorted Cuirassiers’ faces beneath their steel visors, then, at last, the Major shouted, “Fire!”

The forward face of the square disappeared in white smoke. Musket flames stabbed bright and somewhere a horse squealed in awful, gut-wrenching pain. The two front ranks, not bothering to reload, rammed their musket butts into the ground so that their bayonets made a savage hedge of sharpened steel. The rear two ranks reloaded with the speed of men whose lives depended on their musketry.

There was a pause of a heartbeat while the Guardsmen wondered whether a dead horse would slide in hoof-flailing horror to smash their square’s southern face, then, beyond the fringes of the smoke, the horsemen appeared. They had swerved apart, dividing into streams either side of the square. The horses would not crash home, instead the survivors had veered away to gallop between the squares.

“Fire!” That was an officer on the flank of the Guards square. A Cuirassier’s horse was hit in the chest to pump obscenely bright blood as its legs crumpled. The rider, mouth wide open in silent terror, was thrown over its head. Another Cuirassier was being dragged by his stirrup in a spray of blood.

“Fire!” The front face of the square volleyed again, and this time the bullets threw back four Red Lancers. The Lancers had been following the Cuirassiers and seeking the safety of the open ground between the squares, which was not safe at all, but a killing ground that led to the volley fire of yet more squares. The horsemen had been beguiled into the maze of death, yet they were brave men and they still dreamed of carrying the Emperor to victory on their lance points. “Thrust home! Thrust!” Sharpe heard a Lancer officer shout at his men, then saw a group of the red-uniformed horsemen swerve towards the square with their weapons held low. “Thrust hard!”