The 1st battalion returned to Portugal in September 1810 and took part in the Battle of Fuentes de Oñoro in May 1811, the Battle of Arroyo dos Molinos in October 1811 and the Battle of Almaraz in May 1812 as well as 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 the Nive in December 1813 as well as the Battle of Orthez in February 1814 and the Battle of Toulouse in April 1814. The regiment returned to Ireland in July 1814.