In September 1811, Marshal Marmont assembled the army of the north, consisting of 60,000 infantry and 5,000 cavalry, in the neighbourhood of Salamanca, and moved on Ciudad Rodrigo, for the purpose of raising the blockade.

The 2nd battalion of the 5th Foot, guarding Wellington's headquarters, was ordered to march to the front and reinforce two brigades of Portuguese artillery and a squadron of cavalry positioned about 3 miles (4.8 km) from Ciudad Rodrigo.

[4] Major Henry Ridge of the 2nd/5th Foot recalled:[4][5] In consequence of guns being attached to us, I became the senior officer, and having received no orders, whether to retire if attacked (by a superior force), or to defend our post to the last extremity, I thought it prudent, in the first instance, to take the best means in my power to prevent a surprise, and planted the pickets accordingly.

Feeling myself in a very responsible situation, I visited the pickets at daybreak, when I discovered large bodies of the enemy's cavalry coming out of Ciudad Rodrigo, and crossing the Agueda.

At this moment the Duke of Wellington arrived, and after a few minutes of reconnoitring, told Major Ridge that he approved of the arrangements he had made, and would order up a brigade of cavalry in support.

This force, now of about 1,500 men, maintained the post for three hours, although frequently charged by French cavalry, and exposed to heavy fire from the guns of a division of infantry in reserve.

Although the 21st Portuguese regiment were not actually charged by the cavalry, their steadiness and determination were conspicuous, and the Commander of the Forces observed with pleasure the order and regularity with which they made all their movements, and the confidence they showed in their officers.

The Commander of the Forces has been particular in stating the details of this action in General Orders, as, in his opinion, it affords a memorable example of what can be effected by steadiness, discipline, and confidence.