The next engagement was at the Battle of Bussaco on 27 September 1810, where the 1st Division suffered 141 casualties. This was followed by a general retreat to the Lines of Torres Vedras and skirmishes during the Battle of Sobral. The following year, 828 casualties were suffered at the Battle of Fuentes de Oñoro (3–5 May 1811). In early 1812, the division took part in the Siege of Ciudad Rodrigo and then on 22 July fought in the Battle of Salamanca, where it formed the left wing of the army and defended the village of Arapiles. Back-and-forth fighting took place for control of the village that resulted in 158 casualties. In September 1812, the division invested the castle at Burgos. Over the next four weeks, it repulsed several French sorties and launched two failed assaults with heavy losses. By the end of the unsuccessful siege, close to 2,000 casualties had been suffered. A general retreat from Burgos followed, during which the commanding officer Edward Paget was captured. His replacement, William Stewart, delayed part of the retreat when he ignored orders issued by Wellington.
