 Like many others around the time of the First World War, the family anglicised its name, in this case to "Stainer", although Howard's name remained Steiner in official documents, such as his military records.He was a 21-year-old bank clerk in Dulwich when the First World War broke out; in September 1914 he voluntarily enlisted (under the name Leslie Howard Steiner) as a Private with the British Army's Inns of Court Officer Training Corps in London.In February 1915 he received a commission as a subaltern with the 3/1st Northamptonshire Yeomanry Regiment, with which he trained in England until 19 May 1916, when he resigned his commission and was medically discharged from the British Army with neurasthenia.