for the use of the term in philosophy, see Subaltern (postcolonialism)
A subaltern is a military term for a junior officer. 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.