After the end of the First World War, Russell was commissioned into The Royal Irish Fusiliers as a 2nd lieutenant. During the inter-war period, he served in Egypt, India, Sudan, and Palestine. In 1937, he was promoted to major and served as a Brigade Major, until the end of March 1940. After an appointment as a staff officer (GSO2), he became Commander of the 38th (Irish) Infantry Brigade in Britain, North Africa, Sicily, and Italy from July 1942 until February 1944. During this period, he also took command of the ad hoc Y Division during the fighting in North Africa. He was awarded the Distinguished Service Order in 1943, during the Tunisian campaign, and was subsequently mentioned in despatches whilst in Sicily and Italy.