Regimental sergeant major

Regimental sergeant major (RSM) is an appointment 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 Ireland, Australia and New Zealand; and by chief warrant officers (CWO) in the Canadian Forces. Only one WO1/CWO 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 maintaining standards and discipline and acts as a parental figure to his or her subordinates.

Australia
Like most Commonwealth forces, an RSM in the Australian Army is the senior warrant officer of the regiment or battalion, normally a warrant officer class 1.

In addition, the senior warrant officer in the Australian Army holds the unique rank of "warrant officer" (introduced in 1991 and senior to WO1) and the appointment Regimental Sergeant Major of the Army (RSM-A). This appointment, based on the United States Army's practice of appointing a Sergeant Major of the Army, has existed since January 1983, and was originally held by a WO1. It is the equivalent of the Royal Australian Navy's Warrant Officer of the Navy (WO-N) and the Royal Australian Air Force's Warrant Officer of the Air Force (WOFF-AF).

Canada
In the Canadian Forces, the appointment of regimental sergeant major is normally held by an army chief warrant officer. Due to the combined 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 Logistics Branch 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.

As well, it is possible that a master warrant officer may be appointed to an RSM position, in an acting or even official capacity, due to shortages of available CWOs, or in anticipation of a promotion, etc.

Regimental sergeants major in the Canadian Forces are sometimes informally referred to in third person by their appointment, for example "RSM Bloggins" while their commanding officers universally hold the privilege of addressing them as "RSM" (and the practice of doing so by subordinates may be governed by regimental tradition). In no case is an RSM supposed to be addressed simply as "Sergeant Major".

The practice of subordinates addressing the RSM as "Sir" or "Ma'am" applies only to regimental sergeants major who are army or air force CWOs; naval CPO1s are universally addressed as "Chief", regardless of any appointments held.

The equivalent position in a higher formation, such as a brigade-group or Land Force Area, is sometimes termed "regimental sergeant major" (for example, the regimental sergeant major of 1 Canadian Mechanized Brigade Group), but this practice is not universal (for example, the Brigade Sergeant Major of 2 Canadian Mechanized Brigade Group).

Singapore
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:
 * In the presence of another warrant officer; however even under these circumstances, the RSM is treated as the senior warrant officer of the unit while the other warrant officers are recognised as officers.
 * In National service (reserve equivalent) battalions which often have national service junior sergeants fast-tracked for promotion holding the RSM appointment.

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 Malay) 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".

United Kingdom
In the British Army, the RSM is addressed as "Sir" or "Ma'am" by his or her subordinates. In the Household Cavalry, the appointment is regimental corporal major (RCM).

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 )

United States
The equivalent rank in the US Army is a command sergeant major.

The billet, as opposed to rank, of regimental sergeant major exists in the United States Marine Corps, as the senior enlisted adviser to the regimental commander. The rank title is 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.