Just as in any formal title, if you are writing about a specific sergeant major, such as Sergeant Major Plummer in the 7th Cavalry in Vietnam, the words are capitalized.
Non-specific references to sergeants major in general are not capitalized.
You capitalize all rank that is part of a title, for instance:Private QunicySergeant JonesCaptain WallyIt is not necessary to capitalize rank that is not part of a title, for instance."John wanted to become a sergeant in the US Army."
The plural form of sergeant major is sergeant majors.
The correct manner of address is "Sergeant Major," or "Sergeant Major Jones." (Unless, of course, her name is Smith.)
There are three ranks within the pay grade of E9 - Sergeant Major, Command Sergeant Major, and Sergeant Major of the Army. There is only one Sergeant Major of the Army.
There was no such thing as the Sergeant Major of the Marine Corps until 1957. The first Sergeant Major in the Marine Corps was Sergeant Major Archibald Sommers who became the Corps' first Sergeant Major in 1801.
The United States army consists of twelve ranks. They are, in order of rank, Private, Private First Class, Specialist, Corporal, Sergeant. Staff Sergeant, Sergeant First Class, Master Sergeant, First Sergeant, Sergeant Major, Command Sergeant Major, and Sergeant Major of the Army.
There has never been a Sergeant Major General.
There is no such rank as Medic Sergeant Major of the Army. There is a Sergeant Major of the Army and regardless of his specialty, it is just SMA.
Command Sergeant Major Marvin Hill.
Command Sergeant Major is the highest enlisted rank in the US Army
FORSCOM does not have it's own Sergeant Major of the Army - there is only one SMA in the entire Army. The Command Sergeant Major of FORSCOM holds the rank of Command Sergeant Major, and this post is currently filled by CSM Ronald T. Riling. The current Sergeant Major of the Army is SMA Kenneth O. Preston.
Command Sergeant Major.