The siege of _Olivenza_ was undertaken by the fourth division, and the army advanced to drive the French detachments from the province of Estremadura. The British and Portuguese cavalry arrived at _Los Santos_ on the 16th of April, and fell in with a body of French heavy cavalry, when the leading troops of the THIRTEENTH, under Captains Boyse and Macalister, promptly formed and checked the advance of the enemy. The remainder of the regiment, commanded by Colonel Head, quickly formed line,--charged,--cut down many of the enemy,--took two officers and a number of men and horses,--and continued in close and rapid pursuit for several miles, successfully frustrating every attempt of the French to rally, and driving them from the field in utter confusion. The enemy suffered a very severe loss in killed and wounded. The left squadron of the THIRTEENTH, partly formed of the men who had escaped on the 6th instant, had the satisfaction of recapturing some of their horses and accoutrements, and severely revenging their own and their comrades' mischance on some of the very authors of it, who were among their opponents on this occasion. It was observed that these men displayed the most determined gallantry: nothing daunted by the superior numbers of the enemy immediately opposed to them, they rushed fearlessly into their ranks, and committed terrible havoc with their sabres. Captain Doherty had a horse shot under him in this affair. The French commander, whose gallant bearing in leading his men to the attack was long a theme of admiration among the officers who witnessed it, was killed by private _James Beard_ of the regiment, much to the regret of those who had observed his gallantry. On the 19th of April eighteen men, who had escaped from the enemy, rejoined the regiment. The THIRTEENTH Regiment of Light Dragoons remained in advance when the siege of _Badajoz_ was undertaken; but withdrew, with the other cavalry, on the advance of Marshal Soult, (who had collected an army to succour that fortress,) and joined the forces under Marshal Beresford at _Albuhera_, at which place a general engagement was fought on the 16th of May. Two squadrons of the THIRTEENTH were posted near the river above the bridge, with orders to defend it, and had opportunities of making some successful charges against the enemy's cavalry, who attempted to cross the stream. The other two squadrons were posted to keep in check a considerable body of the enemy's cavalry, but they were not seriously engaged, and their loss was limited to one horse killed, and one man wounded.