what is the role of a corporal in the army
Corporal In some militaries, the rank of corporal nominally corresponds to commanding a section or squad of soldiers. However, in the United States Army, the rank of corporal is considered a "lateral promotion" from E-4 Specialist and usually only occurs when the soldier has been selected by a promotion board to become an E-5 Sergeant and is serving in an E-5 billet such as a fireteam leader in a rifle squad. The lateral promotion is used to make the soldier a non-commissioned officer without changing the soldier's pay. As the Table of Organization & Equipment (TO&E) rank of a fire team leader is sergeant and that of squad leader is staff sergeant. In the United States Marine Corps, corporal is the Table of Organization (TO) rank for a rifle fire team leader, machine gun team leader, light mortar squad leader, and assault weapon squad leader, as well as gunner on most larger crew served weapons (i.e. medium mortars, heavy machine guns, and anti-tank missiles), armored vehicles (e.g. tanks, light armored vehicles, and armored assault vehicles), and the two assistant gunners on a howitzer (the gunner is a sergeant).
United States military seniority A type of "positional seniority" exists for military officers who hold top leadership positions of the armed forces. For instance, the Chairman of the Joint Chiefs of Staff is considered the senior most officer of the entire United States military, even though it is possible that contemporaries of the same rank may have earlier dates of rank or time in service. Likewise, heads of various armed service branches are considered senior most within their service; unified commanders are also considered senior most in their respective regions yet not necessarily to each other.