In the summer of 1808 Harris was dispatched to Portugal to participate in the opening actions of the Peninsula War, seeing action in the opening skirmish at Óbidos and subsequently the Battle of Rolica, where Harris' unit was heavily engaged and Harris offers a vivid description of the engagement, at which a number of his close friends were killed. This is followed by a description of the Battle of Vimeiro where he was again heavily engaged and follows the army on the ensuing march to Salamanca and the clash with the French at Sahagún. This is followed by a graphic depiction of the horrific march northwards during the Galician campaign culminating in the Battle of Corunna. Harris and his regiment were amongst the final troops evacuated from the beaches, and they returned to England, where Harris served in recruitment and training positions, thus providing readers with a rare insight into rural Georgian England from a lower class perspective.