Rolt was commissioned as an ensign in the 58th Regiment of Foot on 1 March 1800. He was wounded during the Egyptian Campaign in 1801. He took part in the Siege of Ciudad Rodrigo in January 1812 and the Battle of Badajoz in March 1812 during the Peninsular War, later receiving the Army Gold Cross for Corunna, Nivelle, Nive, Orthes and Toulouse, and the Military General Service Medal with clasps for Egypt, Busaco and Pyrenees.