United States Marine Corps A decade later, in the Mexican–American War (1846–1848), the Marines made their famed assault on Chapultepec Palace in Mexico City, which would be later celebrated as the "Halls of Montezuma" in the Marines' hymn. In the 1850s, the Marines would see further service in Panama and Asia, attached to Matthew Perry's East India Squadron on its historic trip to the Far East. The Marine Corps played a small role in the Civil War (1861–1865); their most prominent task was blockade duty. As more and more states seceded from the Union, about a third of the Corps' officers left the United
Sergeant Major of the Marine Corps Sergeant Major of the Marine Corps Sergeant Major of the Marine Corps (officially abbreviated to SMMC<ref name="ALMAR 016/09"></ref>) is a billet, as well as a unique enlisted grade of rank, with a unique non-commissioned grade of rank insignia, in the United States Marine Corps. In the U.S. Marine Corps, sergeant major is the ninth and highest enlisted rank, just above first sergeant, and equal in grade to master gunnery sergeant, although the two have different responsibilities. A sergeant major typically serves as the unit commander's senior enlisted adviser and to handle matters of discipline and morale among the enlisted Marines.