Smith then fought in the Peninsular War. Joining Wellington's army in January 1813 he attained the brevet rank of major in June 1813, the same month as he fought at the Battle of Vittoria. He was present at the siege of San Sebastian from July to September 1813. In that September he was promoted to lieutenant colonel. He fought at the passage of the Bidassoa in October 1813 and the Nive in December 1813, before returning to England in May 1814.