A subaltern is a chiefly British military term for a junior officer.[1] Literally meaning "subordinate," subaltern is used to describe commissioned officers below the rank of captain and generally comprises the various grades of lieutenant. In the British Army the senior subaltern rank was captain-lieutenant, obsolete since the 18th century. Prior to the Cardwell reforms of the British Army in 1871, the ranks of cornet and ensign were the junior subaltern ranks in the cavalry and infantry respectively. A subaltern takes temporary command of proceedings during Trooping the Colour.
From 1941 to 1949 the Auxiliary Territorial Service (ATS) used the ranks of Second Subaltern and Subaltern which were equivalent to Second Lieutenant and Lieutenant respectively. From 1949 to 1950 the ATS's successor organization, the Women's Royal Army Corps, also used the same ranks until it abandoned them in favour of regular British Army ranks.