A subaltern is a primarily British 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.
Ensign stands for standard or standard-bearer and was, therefore, the rank given to the junior officer who carried, or was responsible for, the flag in battle. This rank has generally been replaced in Army ranks by Second lieutenant. Ensigns were generally the lowest ranking commissioned officer, except where the rank of subaltern itself existed.
In the British Army, the senior subaltern rank was captain-lieutenant, obsolete since the 18th century. Before 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, and were responsible for the flag. A subaltern takes temporary command of proceedings during Trooping the Colour. Within the ranks of subaltern, in a battalion or regiment, a Senior Subaltern may be appointed, usually by rank and seniority, who is responsible for discipline within the junior officer ranks and is responsible to the adjutant for this duty, although the adjutant is ultimately responsible to the commanding officer for the discipline of all the junior officers within the unit.
In critical theory and postcolonialism, subaltern refers to the populations that are socially, politically and geographically outside of the hegemonic power structure of the colony and of the colonial homeland. In describing "history told from below", the term subaltern is derived from Antonio Gramsci's work on cultural hegemony, which identified the groups that are excluded from a society's established structures for political representation and therefore denied the means by which people have a voice in their society.
The terms subaltern and Subaltern Studies entered postcolonial studies through the works of the Subaltern Studies Group, a collection of south Asian historians who explored the political-actor role of the men and women who comprise the mass population—rather than the political roles of the social and economic elites—in the history of south Asia. Marxist historians had already been investigating colonial history as told from the perspective of the proletariat, using the concept of social classes as being determined by economic relations. In the 1970s, subaltern began to denote the colonized peoples of the Indian subcontinent and described a new perspective of the history of an imperial colony as told from the point of view of the colonized rather than that of the colonizers. In the 1980s, the scope of enquiry of Subaltern Studies was applied as an "intervention in South Asian historiography".