In March, 1810, the Light Division was pushed forward towards the Agueda as a corps of observation, being thus employed, under conditions requiring the greatest alertness and activity, on duties essentially those of light troops.
In the absence of definite orders to withdraw behind the Coa, and in order to impede as much as possible the French force besieging Almeida, General Craufurd maintained his forward position until, on July 24th, he was attacked by about six times his own number and forced across the river. In a battle reflecting the greatest credit on all ranks, the division extricated itself from a most dangerous situation in a way troops less highly trained and disciplined could not possibly have done, at a cost of some 300 casualties, the French losing more than double that number.
At the Battle of Busaco, on September 27th following, in a perfectly-timed surprise counter-attack from a concealed position, the 43rd and 52nd completely routed a French column, two private soldiers taking prisoner a French general. In giving the order to charge, General Craufurd called to the 52nd to " revenge the death of Sir John Moore "
The winter was spent on outpost duty in front of the lines of Torres Vedras, from before which the French retired early in March, 1811, closely pursued by the Light Division.
The 43rd and 52nd were engaged with the enemy at Pombal (March 11th), Redinha (March 12th), Cazal Novo and Miranda de Corvo (March 14th), and on March 15th at Foz d'Aronce.
On March 25th the 2nd Battalion 52nd joined the Light Division. The combat of Sabugal followed on April 3rd, and on May 5th was fought the Battle of Fuentes D'Onor, where the regiments of the Light Division, in squares, proved themselves as good as at their own open order work. In July a draft of nearly four hundred strong joined the 43rd from its 2nd Battalion at home. The rest of 1811 was spent in preparing for the capture of Ciudad Rodrigo.
In November Lieut.-Colonel John Colborne joined the 52nd on appointment to command, in place of Lieut.-Colonel Barclay, who had died of wounds received at Busaco.
The Siege of Ciudad Rodrigo began on January 8th, 1812, and on the evening of the 19th the two breaches were stormed, the Greater Breach by the 3rd Division, and the Lesser by the Light Division, but General Craufurd, while directing the attack from an exposed position, received the wound from which several days later, he died—a loss to the Army, and to the Light Division especially, for which no victory could compensate. The casualties in the 43rd amounted to 54, and in the 52nd (both battalions) to 52, including Lieut.-Colonel Colborne.