The regiment embarked for Portugal in July 1808 to serve under General Sir Arthur Wellesley in the Peninsular War. The regiment fought at the Battle of Roliça in August 1808, the Battle of Vimeiro later that month and the Battle of Talavera, where it won the nickname "Old Stubborns", in July 1809. The regiment went on to fight at the Battle of Bussaco in September 1810 before falling back to the Lines of Torres Vedras. It saw action again at Battle of Fuentes de Oñoro in May 1811, the Siege of Ciudad Rodrigo in January 1812 and the Siege of Badajoz in March 1812 before fighting at the Battle of Salamanca in July 1812 and the Battle of Vitoria in June 1813. It then pursued the French Army into France and fought at the Battle of the Pyrenees in July 1813, the Battle of Nivelle in November 1813 and the Battle of Orthez in February 1814 as well as the Battle of Toulouse in April 1814. The regiment returned home in June 1814.