After two years at Liegnitz, Ravenstein transferred to the 155th Infantry Regiment as a battalion adjutant officer. On the outbreak of World War I, his regiment marched into Belgium and he fought in the Battle of Longwy on 22 August 1914. He subsequently saw action in the Battle of Verdun. In 1915 he was promoted to "oberleutnant" and was soon commanding a company in his regiment. Apart for periods of leave, he served continuously on the Western Front throughout the war. He proposed to Elisabeth in 1917 and married her early the following year while on leave.