Warrant officers are a grade of officer, generally found in all three services, whose authority stems from a warrant, usually signed by a government minister or representative of a service board. As such they rank below commissioned officers but above NCOs or petty officers. Warrant officers originated in the 17th century, as ‘standing officers’ on warships—like the sailing master, carpenter, and gunner—appointed because of specific technical skills and holding Navy Board warrants.
Their use extended into armies in two ways. First, as in the naval context, to emphasize particular skills, especially in logistic and administrative areas: for many years the British army's senior warrant rank was that of Conductor in the Army Ordnance Corps (later Royal Army Ordnance Corps). Secondly, to grant added status to individuals whose functions were clearly more important than those of NCOs but could not be granted commissioned rank. The rank of adjutant (not to be confused with the post of adjutant, held by a commissioned officer in the British army) was introduced into the French army in the 18th century, and in the 19th the British Regimental Sergeant Major (RSM), initially simply the most senior NCO, became a warrant officer.
The British army created the warrant rank of Company Sergeant Major (CSM) in 1913: CSMs ranked as Warrant Officers Class 2 and RSMs as Warrant Officers Class 1. The rank of Warrant Officer Class 3, Platoon Sergeant Major, was introduced just before WW II to produce warrant officer platoon commanders, but was not a success and was allowed to lapse. Here the British were influenced by the success of German Unteroffiziere mit Portepee (‘NCOs with (an officer's) sword knot’) in WW I, but the notion did not transplant into the British army where distinctions between commissioned and non-commissioned rank were often as much social as military.
The use of warrant officers by the US army reflects the older use of the rank as a means of giving pay and status to an individual whose technical skill may not be mirrored by a need to exercise wide command responsibility. Warrant officers were recruited in large numbers during the Vietnam war to fly helicopters.
The status of warrant officers is reflected by their uniforms and badges of rank which are often more like those of officers than those of NCOs and men: in the British army the break point comes between WO1 and WO2. In some forces they mess with the officers and, like them, are saluted.
— Richard Holmes
