While the regiment was occupying quarters at Monforte, Ciudad Rodrigo was besieged and captured by storm in January, 1812. When Badajoz was besieged, the regiment advanced and formed part of the covering army. During the advance and the subsequent operations, the Thirteenth were employed in the arduous outpost duties of the army, and engaged in affairs and skirmishes, which were of frequent occurrence, owing to the constant alerts occasioned by the enemy's cavalry in their front, who took every opportunity of endeavouring to cut off the foraging parties, patroles, &c.
In the advance to Merida, in March, the German hussars, having fallen in with the French cavalry, commenced skirmishing, and pushed them through the town and across the bridge. Major-General Long ordered the Thirteenth to gain the front at a gallop, which they did, and, crossing the Guadiana at a deep ford, formed and charged the enemy, who broke and fled, the regiment following, and constantly skirmishing with them till near dark, when it was ordered to discontinue the pursuit.
In April the fortress of Badajoz was taken by storm, and the army afterwards quitted Estremadura, when the Thirteenth Dragoons were again left with Lieut.-General Hill.
The regiment was employed in the enterprise against the enemy's works, which protected the bridge across the Tagus at Almaraz. These were destroyed on the 19th of May, to render the communications between the French armies more difficult. On this occasion the Thirteenth advanced to the high road by the pass of Mirabete, and were in reserve while the forts were stormed.
During the summer and autumn of this year, the services of the regiment were connected with the movements of the troops under Lieut.-General Sir Rowland Hill; it performed many long marches, took part in a few skirmishes, and penetrated into the interior of Spain.
In July the Thirteenth, in brigade with the ninth dragoons and second German hussars, were engaged in a second successful affair with the enemy at Usagre; and in one of the several skirmishes, Serjeant Shaw of the Thirteenth distinguished himself by his gallantry. Honourable mention is also made of the firm and orderly retreat of a squadron of the regiment, commanded by Captain Shapland Boyse, before a vastly superior body of the enemy's cavalry, by whom they were hard pressed for a considerable distance in the neighbourhood of Ocana.
A singular circumstance occurred when the regiment was bivouacked in the neighbourhood of Aranjuez: the horses, being unbridled for the convenience of feeding, were linked, and the officers and men were reposing from their fatigues, when the Second German Hussars, who had been ordered to join Lord Wellington's army, filed past; the Thirteenth immediately sprung up, and actuated by the impulse of the moment, greeted their old comrades with a hearty parting cheer, which so alarmed the horses that four troops broke loose, notwithstanding every exertion made to detain them, and dispersed over the open country, galloping about in squads, and scattering bridles, pistols, carbines, &c., in every direction. The scene was truly ludicrous; but this inconsiderate act might have been attended with serious consequences, as the enemy was in force, particularly in cavalry, in Aranjuez. The horses, some of which had strayed to a distance of four or five leagues, and had been secreted by the Spaniards, were all brought back in the course of the day, and scarcely an article of equipment was lost. The exertions of Adjutant Holmes on this occasion are particularly mentioned.
At the close of the campaign, when the main army withdrew from Burgos, the troops under Lieut.-General Hill also fell back, and the whole were united at Salamanca.
The Thirteenth were in reserve in the affair at Alba de Tormes, and were engaged, with the rear guard, in skirmishing with the enemy during the retrograde movement of the army to the Agueda. The horses suffered severely from want of forage. After retiring beyond the confines of Spain, the regiment marched to the Alemtejo, and was quartered at Crato, where it received a reinforcement of officers, men, and horses, from England in December.