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 and also to junior officers, even though they technically outrank the RSM.

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 of the Army" (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).

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