The combat of Majalahonda (11 August 1812) was the only significant fighting during Wellington's advance on Madrid in the aftermath of the battle of Salamanca, and saw his leading cavalry force come under attack by a French force that had been sent out to discover if Wellington was indeed on his way.
By 10 August King Joseph had already decided to evacuate Madrid in the face of Wellington's advance, but he wanted to make sure that Wellington was actually advancing towards him with his main army before leaving the city. Accordingly he sent General Treillard with 2,000 cavalry, supported by Palombini's Italian Division, to attack Wellington's advance guard and to capture prisoners.
Wellington's advance guard was made up of D'Urban's Portuguese cavalry, the heavy dragoons of the King's German Legion, Macdonald's horse artillery and one light battalion of the KGL. On 9 August D'Urban occupied the Escurial palace, and found the French rearguard at Las Rosas and Majalahonda. On the following day D'Urban advanced a little closer to the French, but Wellington had ordered him not take any risks until the main army was closer at hand.
Early on 11 August D'Urban attacked the existing French outposts, which were held by 700 dragoons under Reiset. D'Urban had a similar number of troops at hand, but also had some artillery, and he was able to force the French out of Las Rosas and then out of Majalahonda. That placed him only seven miles from Madrid, with orders to get to within three miles before stopping. The last thing D'Urban expected was to be attacked, so he ordered his Portuguese troops to rest in Majalahonda. The German troops reached Las Rosas, where they did the same.
Unfortunately for D'Urban, the French were now moving, and at just before 4pm a force of around 2,000 cavalry (19th and 22nd Dragoons, Italian Dragons le Napoléon, 1st Westphalian Lancers and Reiset's men), appeared outside Majalahonda. D'Urban's men just about had enough time to form up before the French hit. He posted one squadron of Portuguese troops in front as skirmishers, five in his main line and one on his left to defend the horse artillery.
The French attacked in three lines. D'Urban led a counter-charge, but his troops melted away just before the clash actually took place, leaving only their officers going forwards. Two of the Portuguese commanders, Visconde de Barbacena and Colonel Lobo, were captured at this stage, and D'Urban only narrowly escaped. The French then pursued the defeated Portugeuse back towards the Germans at Las Rosas.
The German heavy cavalry was also caught by surprise. They had only just formed up when Reiset's men, in the lead of the French charge, attacked, and threatened to repeat their earlier success. They were stopped by a mix of fire from the light infantry in the village and the performance of a small part of the line. Reiset was forced to order his men back to reform, and this gave the Germans time to form their line properly. D'Urban has also been able to rally some of his Portuguese troops.
The second French attack was repulsed by the Germans, but once again the Portuguese soon retreated. Treillard fed his second line into the battle, and they forced the Germans back to the village. However the French were then stopped by light infantry fire from the buildings.
Treillard still had his third line, but at this point Ponsonby's cavalry brigade and the first troops from the 7th Division came into sight. Treillard retreated at great speed, abandoning the three guns the French had captured earlier in the day. However they had achieved their main objective - Treillard was able to inform King Joseph that Wellington was advancing on Madrid in person. With that confirmed, Joseph left Madrid late on the same day, while Wellington made a triumphant entry on 12 August.