Regimental sergeant major (RSM) is an appointment that may be held by warrant officers class 1 (WO1) in the British Army, the British Royal Marines and in the armies of many Commonwealth and former Commonwealth nations, including Australia, Kenya and New Zealand. It is also an appointment that may be held by chief warrant officers (CWO) in the Canadian Forces and warrant officers of any grade in the Singapore Armed Forces, and is a rank in itself in the Irish Defence Forces and formerly in the British Army, Royal Marines and United States Army. Only one warrant officer holds the appointment of RSM in a regiment or battalion, making him the senior warrant officer; in a unit with more than one WO1, the RSM is considered to be "first amongst equals". The RSM is primarily responsible for assisting their commander for maintaining standards and discipline amongst the non-commissioned members and acts as a parental figure to their subordinates.
Like most Commonwealth forces, a regimental sergeant major (RSM) in the Australian Army is usually a warrant officer class 1 and holds a special position within a regiment or battalion as the senior non-commissioned adviser to the unit's commanding officer. They are known as the regimental sergeant major regardless of whether the unit is a regiment or battalion. The RSM has leadership, discipline and welfare responsibilities of up to 650 officers and soldiers, as well as the maintenance of their equipment.
The most senior warrant officer in the Australian Army is titled Regimental Sergeant Major of the Army.
In the Canadian Forces, the appointment of regimental sergeant major is normally held by an army chief warrant officer. Due to the integrated nature of the Canadian Forces, however, it is not impossible for an air force chief warrant officer or a naval chief petty officer 1st class to rise to that post, especially in units with a high number of support trades personnel; examples might include a Royal Canadian Logistics Service CPO1 being appointed RSM of a service battalion, or an air force Communications and Electronics Branch CWO appointed to the position in a communication regiment.
RSMs are generally address as "RSM" or "Mr" or "Ms" by officers, and as "Sir" or "Ma'am" by subordinates (which applies only to regimental sergeant majors who are army or air force CWOs; naval CPO1s are universally addressed as "Chief", regardless of any appointments held).
Like most Commonwealth forces, the RSM in the Singapore Armed Forces is usually the most senior warrant officer in the unit. Depending on the size of the unit, RSMs can be third, second, first, master, or senior warrant officers.
Exceptions to this are:
During exercises and operations, the role of the RSM is to organize the battalion for movement, and to assist the unit S1 (manpower officer) in manpower administration.
In camp, he is the master of drill, parades and ceremonies. He supervises the company sergeants major and platoon sergeants in the instruction of drill, and is in charge of the organization of formal parades. On the parade square, the RSM, with his pace stick, is "king" as he has authority over all soldiers and even has the power to order punishment for subalterns (junior commissioned officers such as captains and lieutenants). In fact, the RSM may conduct "subalterns' parades" - private sessions for junior officers to perfect their foot and sword drills away from the critical eyes of the other ranks.
Senior officers may address him simply as "RSM", while, as a warrant officer, he is addressed as "Sir" by those junior in rank. Traditionally, all warrant officers, with or without an appointment as RSM or CSM, are addressed as "Encik" ("mister" in English) by officers and other ranks although this is an informal right which is not to be assumed. Sometimes, lower ranked NCOs who are not warrant officers but who are holding the appointment of CSM may also be given the honour of being addressed as "Encik." Nevertheless, all specialists and warrant officers holding sergeant-major appointments should be addressed as "sergeant-major".
In the Royal Marines, regimental sergeant major was an actual rank (and equivalent to warrant officer class I in the Army) until the Royal Marines themselves re-adopted the ranks of warrant officer classes I and II in 1973 (although the term continued to be used interchangeably for warrant officers class I until at least 1981). The most senior warrant officer in the Royal Marines holds the appointment of Corps Regimental Sergeant Major.
The rank of regimental sergeant major existed in the United States Army during World War I. The rank was phased out in the early 1920s.
Unlike many countries, US sergeants major are not classified as warrant officers. The warrant officer ranks of the United States military are unusual, in that they are considered officers rather than NCOs and occupy a special range below second lieutenants and ensigns: they rank "with but below" lieutenants and ensigns.