Definition/Scope: A Corps "core" spelled the same as singular; from French, from the Latin corpus "body") is either a large formation, or an administrative grouping of troops within an armed force with a common function such as Artillery or Signals representing an arm of service. Corps may also refer to a branch of service such as the United States Marine Corps or the Corps of Royal Marines to name a couple. In many armies, a corps is a battlefield formation composed of two or more divisions, and typically commanded by a lieutenant general. During World War I and World War II, due to the large scale of combat, multiple corps were combined into armies which then formed into army groups. In the US and in some European armed forces the number of a corps is traditionally indicated in Roman numerals (e.g., XXI Corps). The first corps in the United States Army were legalized during the American Civil War by an Act of Congress on July 17, 1862, but Major General George B. McClellan designated six corps organizations within his Army of the Potomac that spring. Prior to this time, groupings of divisions were known by other names, such as "wings" and "grand divisions". The terminology "Army Corps" was often used. These organizations were much smaller than their modern counterparts. They were usually commanded by a major general, were composed of two to six divisions, although predominantly three, and typically included from 10,000 to 15,000 men. Although designated with numbers that are sometimes the same as modern U.S. Army corps, there is no direct lineage between the 43 U.S. corps of the Civil War and those with similar names in the 20th century due to Congressional legislation caused by the outcry from Grand Army of the Republic veterans during the Spanish-American War. In the Confederate States Army, corps were authorized in November 1862. They were commanded by lieutenant generals and were usually larger than their Union Army counterparts because their divisions contained more brigades, each of which could contain more regiments. All of the Confederate corps at the Battle of Gettysburg, for instance, exceeded 20,000 men. However, for both armies, unit sizes varied dramatically with attrition throughout the war. As of 2003, the United States Army has four field corps. The structure of a field corps is not permanent; many of the units that it commands are allocated to it as needed on an ad hoc basis. On the battlefield, the field corps is the highest level of the forces that is concerned with actually fighting and winning the war. Higher levels of command are concerned with administration rather than operations, at least under current doctrine. The corps provides operational direction for the forces under its command. Corps are designated by consecutive Roman numerals. The present active corps in the US Army are I Corps ("eye core"), III Corps, V Corps (scheduled to deactivate in 2008 or 2009), and XVIII Airborne Corps; their numbers derive from four of the 30-odd corps that were formed during World War II. It also refers to a grouping of specialized troops such as the Army Corps of Engineers and the United States Marine Corps.
Related Terms:I Corps