Shortly afterwards Graham joined the army under Wellington, and was appointed second in command. In January 1812, he took part in the siege and capture of Ciudad Rodrigo, and Wellington declared that he was much indebted to him for the success of the enterprise. Three months later he and his friend General Hill received the Order of the Bath. A problem with his eyes, from which he had been suffering for some time, made it necessary for Graham to return home at this juncture.