曹長
In the United States Marine Corps, sergeant major is the ninth and highest enlisted rank, just above first sergeant, and equal in pay grade to master gunnery sergeant, although the two have different responsibilities. Sergeant major is both a rank and a military billet. Marine Corps sergeants major serve as the senior enlisted marine in the Corps' units of battalion, squadron or higher echelon, as the unit commander's senior enlisted advisor and to handle matters of discipline and morale among the enlisted marines. Sergeant Major of the Marine Corps is a separate and unique position.