what is the highest enlisted rank in the marines
United States Marine Corps rank insignia The Sergeant Major of the Marine Corps is a billet and with it carries a special rank insignia, conferred on the senior enlisted Marine of the entire Marine Corps, personally selected by the Commandant of the Marine Corps.[6] It and the Marine Gunner are the only billets which rate modified rank insignia in place of the traditional rank insignia.[citation needed]
Corporal The history of the rank of corporal in the USMC roughly parallels that of the U.S. Army until 1942. From 1775 until WWII, the Marine Corps used essentially the same rank and organizational structure as its common British and colonial forebears with the Army, as well as the later Continental and U.S. armies. In 1942, as the Army modified its triangular division infantry organization to best fight in the European/North African/Middle Eastern Theatre the Marine Corps began modifying the triangular division plan to best employ its amphibious warfare doctrine in the Pacific Theatre. This meant that for the Corps, squad leaders would remain as sergeants and that the rifle squad would be sub-divided into three four-man fire teams each led by a corporal.