[5] Campbell entered the army as an ensign in the 6th Regiment of Foot in 1795, of which his father was then lieutenant-colonel, and was promoted lieutenant on 4 April 1796.

[1] Campbell again saw action with the 6th during the Peninsular War, fighting at Roliça and Vimeiro, and taking part in the advance and retreat of Sir John Moore.

Promoted major on 1 April 1813, Campbell and the 6th fought at Vitoria (21 June 1813), and owing to the wounding of the colonel, took command of the regiment.

[1] After the war, he received a gold medal for his conduct at the Battle of the Pyrenees and was awarded the CB.

[1] Campbell was appointed deputy quartermaster-general in Ireland in 1830, and was promoted major-general in 1841, receiving command of the Athlone district.