Battle of Waterloo
His troops consisted of 74,326 men: 53,607 infantry, 13,400 cavalry, and 5,596 artillery with 156 guns plus engineers and staff. Of these, 27,985 (38%) were British, with another 7,686 (10%) from the King's German Legion (KGL). All of the British Army troops were regular soldiers, and the majority of them had served in the Peninsula. Of the 23 British line infantry regiments in action, only four (the 14th, 33rd, 69th, and 73rd Foot) had not served in the Peninsula, and a similar level of experience was to be found in the British cavalry and artillery.   Chandler asserts that most of the British veterans of the Peninsular War were being transported to North America to fight in the War of 1812. In addition, there were 21,035 (28.3%) Dutch-Belgian and Nassauer troops, 11,496 (15.5%) from Hanover and 6,124 (8.2%) from Brunswick.
Many of the troops in the Coalition armies were inexperienced. The Dutch army had been re-established in 1815, following the earlier defeat of Napoleon. With the exception of the British and some men from Hanover and Brunswick who had fought with the British army in Spain, many of the professional soldiers in the Coalition armies had spent some of their time in the French army or in armies allied to the Napoleonic regime. The historian Alessandro Barbero states that in this heterogeneous army the difference between British and foreign troops did not prove significant under fire.
Wellington was also acutely short of heavy cavalry, having only seven British and three Dutch regiments. The Duke of York imposed many of his staff officers on Wellington, including his second-in-command, the Earl of Uxbridge. Uxbridge commanded the cavalry and had carte blanche from Wellington to commit these forces at his discretion. Wellington stationed a further 17,000 troops at Halle, 8 miles (13 km) away to the west. They were mostly composed of Dutch troops under the Prince of Orange's younger brother, Prince Frederick of the Netherlands. They were placed as a guard against a wide flanking movement and also to act as a rearguard if Wellington was forced to retreat towards Antwerp and the coast.
The Prussian army was in the throes of reorganisation. In 1815, the former Reserve regiments, Legions, and Freikorps volunteer formations from the wars of 1813–1814 were in the process of being absorbed into the line, along with many Landwehr (militia) regiments. The Landwehr were mostly untrained and unequipped when they arrived in Belgium. The Prussian cavalry were in a similar state. Its artillery was also reorganising and did not give its best performance—guns and equipment continued to arrive during and after the battle.
Offsetting these handicaps, the Prussian army had excellent and professional leadership in its general staff. These officers came from four schools developed for this purpose and thus worked to a common standard of training. This system was in marked contrast to the conflicting, vague orders issued by the French army. This staff system ensured that before Ligny, three-quarters of the Prussian army had concentrated for battle with 24 hours' notice.
After Ligny, the Prussian army, although defeated, was able to realign its supply train, reorganise itself, and intervene decisively on the Waterloo battlefield within 48 hours. Two-and-a-half Prussian army corps, or 48,000 men, were engaged at Waterloo; two brigades under Bülow, commander of IV Corps, attacked Lobau at 16:30, while Zieten's I Corps and parts of Pirch I's II Corps engaged at about 18:00.

Battlefield: The Waterloo position chosen by Wellington was a strong one. It consisted of a long ridge running east–west, perpendicular to, and bisected by, the main road to Brussels. Along the crest of the ridge ran the Ohain road, a deep sunken lane. Near the crossroads with the Brussels road was a large elm tree that was roughly in the centre of Wellington's position and served as his command post for much of the day. Wellington deployed his infantry in a line just behind the crest of the ridge following the Ohain road.
Using the reverse slope, as he had many times previously, Wellington concealed his strength from the French, with the exception of his skirmishers and artillery. The length of front of the battlefield was also relatively short at 2.5 miles (4 km). This allowed Wellington to draw up his forces in depth, which he did in the centre and on the right, all the way towards the village of Braine-l'Alleud, in the expectation that the Prussians would reinforce his left during the day.

In front of the ridge, there were three positions that could be fortified. On the extreme right were the château, garden, and orchard of Hougoumont. This was a large and well-built country house, initially hidden in trees. The house faced north along a sunken, covered lane (usually described by the British as "the hollow-way") along which it could be supplied. On the extreme left was the hamlet of Papelotte.
Both Hougoumont and Papelotte were fortified and garrisoned, and thus anchored Wellington's flanks securely. Papelotte also commanded the road to Wavre that the Prussians would use to send reinforcements to Wellington's position. On the western side of the main road, and in front of the rest of Wellington's line, was the farmhouse and orchard of La Haye Sainte, which was garrisoned with 400 light infantry of the King's German Legion. On the opposite side of the road was a disused sand quarry, where the 95th Rifles were posted as sharpshooters.
Wellington's forces positioning presented a formidable challenge to any attacking force. Any attempt to turn Wellington's right would entail taking the entrenched Hougoumont position. Any attack on his right centre would mean the attackers would have to march between enfilading fire from Hougoumont and La Haye Sainte. On the left, any attack would also be enfiladed by fire from La Haye Sainte and its adjoining sandpit, and any attempt at turning the left flank would entail fighting through the lanes and hedgerows surrounding Papelotte and the other garrisoned buildings on that flank, and some very wet ground in the Smohain defile.
The French army formed on the slopes of another ridge to the south. Napoleon could not see Wellington's positions, so he drew his forces up symmetrically about the Brussels road. On the right was I Corps under d'Erlon with 16,000 infantry and 1,500 cavalry, plus a cavalry reserve of 4,700. On the left was II Corps under Reille with 13,000 infantry, and 1,300 cavalry, and a cavalry reserve of 4,600. In the centre about the road south of the inn La Belle Alliance were a reserve including Lobau's VI Corps with 6,000 men, the 13,000 infantry of the Imperial Guard, and a cavalry reserve of 2,000.
In the right rear of the French position was the substantial village of Plancenoit, and at the extreme right, the Bois de Paris wood. Napoleon initially commanded the battle from Rossomme farm, where he could see the entire battlefield, but moved to a position near La Belle Alliance early in the afternoon. Command on the battlefield (which was largely hidden from his view) was delegated to Ney.

Battle: 

Preparation: Wellington rose at around 02:00 or 03:00 on 18 June, and wrote letters until dawn. He had earlier written to Blücher confirming that he would give battle at Mont-Saint-Jean if Blücher could provide him with at least one corps; otherwise he would retreat towards Brussels. At a late-night council, Blücher's chief of staff, August Neidhardt von Gneisenau, had been distrustful of Wellington's strategy, but Blücher persuaded him that they should march to join Wellington's army. In the morning Wellington duly received a reply from Blücher, promising to support him with three corps.
From 06:00 Wellington was in the field supervising the deployment of his forces. At Wavre, the Prussian IV Corps under Bülow was designated to lead the march to Waterloo as it was in the best shape, not having been involved in the Battle of Ligny. Although they had not taken casualties, IV Corps had been marching for two days, covering the retreat of the three other corps of the Prussian army from the battlefield of Ligny. They had been posted farthest away from the battlefield, and progress was very slow.
The roads were in poor condition after the night's heavy rain, and Bülow's men had to pass through the congested streets of Wavre and move 88 artillery pieces. Matters were not helped when a fire broke out in Wavre, blocking several streets along Bülow's intended route. As a result, the last part of the corps left at 10:00, six hours after the leading elements had moved out towards Waterloo. Bülow's men were followed to Waterloo first by I Corps and then by II Corps.