The combat of Villagarcia (11 April 1812) was a clash between Drouet's 'corps of observation', watching the third siege of Badajoz, and a British cavalry force.
When Wellington began the third British siege of Badajoz on 16 March, Marshal Soult slowly gathered together an army, and advanced towards Villafranca. He hoped to meet up with Marmont and then used their combined armies to lift the siege. However Marmont had been forbidden to move south, and Badajoz fell on 6 April, far sooner than expected. Soult was also threatened by several Spanish armies, which appeared to pose a real danger to Seville. On 7 April abandoned his position at Villafrance, and retreated east to save Seville.
He left behind General Drouet, with two divisions (Drouet and Daricau), to act as a corps of observation. His orders were to occupy a forward position that would keep open the lines of communication between Soult and Marmont, ideally stopping somewhere around Llerena.
Wellington sent a sizable force to push Drouet out of his forward position. This was commanded by Stapleton Cotton, and contained Le Marchant's and Slade's heavy cavalry brigades and Ponsonby's light cavalry brigades.
Drouet had a cavalry screen posted in front of his infantry, with Lallemand's dragoons forming the first line and Perreymond's hussars and chasseurs in the second line.
The British advanced with Ponsonby directly facing Lallemand and Le Marchant on the right. Lallemand appears to have been unaware of Le Marchant's men, and prepared to fight Ponsonby. Just as the battle began, the first of Le Marchant's men arrived on the French left, hit their line front the flank and rolled it up. The French retreated half way from Villagarcia to Llerena, where they rallied around the 2nd Hussars.
Cotton had managed to stop his men from getting out of hand, and he was able to force the French out of this second line. However the surviving French cavalry then formed up a new line in front of Llerena, supported by Drouet's infantry. The French now had 12,000 men, while Cotton only had cavalry. As a result the fighting ended. Cotton's men kept a watch on the French position, before later in the same day the French began to retreat. Drouet didn't stop until he had left Estremadura completely.
The French lost 53 killed and wounded and 136 prisoners in the fighting, while the British lost 14 dead and 37 wounded. The British didn't pursue Drouet, as Wellington had now decided to move his army north to deal with Marmont instead, so General Hill was left in the south in command of a British 'corps of observation', while the main army moved north at the start of the campaign that would lead to the battle of Salamanca.