A cheer rose up from end to end along the allied line at the sight of the elite French infantry pouring down the slope. Arthur stared at the sight, not quite believing his eyes and not immediately grasping what it meant. It was Uxbridge who reacted first.

‘Boney’s beaten! By God, he’s beaten!’ He grasped Arthur’s arm. ‘Your grace!’

Before Arthur could reply the sound of a cannon ball passing close by filled the air with its drone, and he felt Uxbridge’s fingers suddenly dig into his sleeve.

‘I’m hit . . .’ Uxbridge looked at him, wide-eyed. ‘I’m hit.’

Arthur reached over and grabbed his shoulder to steady him. ‘You there!’ he called to a gun crew who had retreated to Maitland’s brigade. ‘Help me. Get this officer to the rear!’

The gunners eased Uxbridge down from his saddle and laid him on the ground. Arthur saw that his knee had been smashed by a roundshot and was now a bloody mess of bone and muscle. The artillery crew picked him up and Uxbridge let out a deep groan as they moved off. Arthur turned back towards the battle and looked down the slope. There were still four battalions of guardsmen formed up, but they were now slowly falling back, covering the retreat of their stricken comrades. Over to the right, the garrison of Hougoumont still held on as they fought to contain the fire that had broken out earlier. To the left, the French were abandoning La Haye Sainte and retreating down the road to Charleroi. Over to the east Arthur could clearly see the columns of Prussians pushing back the remnants of the Young Guard.

‘By God,’ he muttered to himself. ‘We’ve done it . . . We’ve won.’

Somerset came riding up, his face alight with excitement. ‘Your grace, d’you see? The French are broken. They’re retreating!’

Arthur could not restrain himself a moment longer. The strain and anxiety of the terrible contest was lifted from him and he felt a wave of elation course through his body. Somerset was grinning at him.

‘What are your orders, your grace?’

Arthur took off his hat and waved it above his head, in the direction of the enemy. ‘Give the order to every man you can find - general pursuit.’

As the word spread swiftly through the ranks of the men who had held the ridge all day the army swept forward, infantry mixed with cavalry as they chased after the French. Arthur rode with them and at his approach his men cheered him for all they were worth. The French spilled out across the landscape as they desperately tried to escape, abandoning their guns, caissons and wagons along with their wounded. Arthur searched for sign of Bonaparte, but the Emperor’s distinctive white horse was nowhere to be seen. He reined in briefly at La Belle Alliance, where men from one of the Dutch cavalry regiments were busy ransacking what was left of the French headquarters in the gathering dusk. A hundred yards further down the road he came upon the first of the Prussian soldiers. They were busy bayoneting wounded Frenchmen and glanced up at him suspiciously until they realised from his beaming smile that he could hardly be an enemy. A short distance further on he saw a cluster of Prussian officers on horseback. At their head was a stiff-backed, elderly man with a fabulous growth of silvery hair on his cheeks.

‘Marshal Blьcher!’ Arthur called out at once, raising his hand.

The Prussian officers turned towards him and as he reined in Blьcher recognised Arthur in turn, edged his mount over and embraced him. Neither man spoke the other’s language, and Blьcher blurted out, ‘Mein lieber Kamerad! ’ And then, in a guttural accent, ‘Quelle affaire!’

Arthur laughed and clapped him on the shoulder. ‘Bonaparte is beaten. Once and for all.’ He paused and shook his head. ‘But it was a damned close run thing!’

The pursuit continued after nightfall. Arthur’s troops were too exhausted to go far and gradually abandoned the task to the Prussians. A pale moon rose over the battlefield and cast a ghostly silver-grey hue over the fields of death where the bodies of tens of thousands lay stiffening in the cool air. The ride along the road back to Waterloo filled Arthur with a numbing sense of unreality. The air over this same ground had earlier been filled with the deafening roar of guns, the crack of muskets and the rhythmic signals of bugles and drums.

It was quiet now, but far from silent. Many of the wounded lay groaning, crying out or simply talking to themselves. Some babbled incoherently, driven mad by pain or the trauma of the day’s experiences. Here and there small parties of soldiers searched for wounded survivors of their regiments to carry back to the dressing stations behind the ridge and in the village of Waterloo. The defenders of Hougoumont had emerged from their strongpoint and left the fire in the barns to burn itself out, the flames still casting a glow across the bodies piled around the house and gardens.

Arthur shivered as he reached the shattered limbs of the elm tree on the ridge. He looked back across the battlefield one last time and then spurred Copenhagen into a trot as he made for the inn that served as his headquarters at Waterloo. Somerset had arrived shortly before him and could not hide his relief that his commander was unhurt. Supper had been prepared by the innkeeper and the headquarters servants had laid the table for Arthur and his staff officers with the best silverware and china. He sat down at the head of the table, and Somerset took the seat to his left.

‘Where are the others?’ Arthur asked. ‘My aides?’

‘They will be along directly,’ Somerset replied, then frowned. ‘At least, some will, I’m sure.’

Weariness had set into every bone in Arthur’s body and he managed to eat little of the cold meat and bread that was put in front of him. Servants came and went and a few officers arrived with messages, which Somerset took and read, only handing on the most important to Arthur. Midnight came, but no more of his staff officers returned to headquarters. Arthur turned to Somerset.

‘Thank God I do not know how it feels to lose a battle, but few things can be more painful than to win at the cost of so many fine officers, and friends.’

‘Yes, your grace.’ Somerset nodded. ‘It is a hard thing to take.’

‘I must sleep,’ Arthur said quietly. ‘Then I will write my report. England must know the result. Wake me at the third hour.’

Somerset nodded.

Arthur rose stiffly from his seat and winced. He stood for a moment, staring at the empty places along the table and feeling a terrible emptiness within him. ‘I pray that I have fought my last battle.’

Then he smiled bleakly at Somerset and crossed the room to one of the wooden pallets that had been covered with straw-filled mattresses to serve as beds. He was too tired to take off his boots and eased himself down, lying on his back. His eyes ached terribly, and he closed them for a moment, and was deeply asleep shortly afterwards, his snores filling the room.

‘Your grace, wake up.’

Arthur stirred, blinking his eyes open. Somerset was leaning over him.

‘What time is it?’

‘Just past midnight, your grace.’

Arthur sighed. ‘I was to be woken at three.’

‘Yes, but we have a visitor, your grace.’ Somerset turned and gestured to a figure standing just inside the door of the inn. By the light of the lantern hanging above the table Arthur saw that he was wearing the uniform of a French officer. Arthur swung his legs over the side of the makeshift bed and stared at the man. He was tall and thin, some years older than Arthur and dark-featured. A bloody rag was tied around his head.

‘Who the devil are you?’

‘Colonel Chaumert, of the Imperial Guard, your grace.’ The Frenchman bowed his head.

‘What are you doing here?’

‘I have a message for you.’ He glanced at Somerset.‘It is for your ears only.’