: This article is about a military unit. For alternative meanings, see Corps (disambiguation).
A Corps ( "core"; plural 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, the Corps of Royal Marines, the Honourable Corps of Gentlemen at Arms, or the Corps of Commissionaires.

Military formation

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 armies with numbered corps the number is traditionally indicated in Roman numerals (e.g., XXI Corps).

Australia

In the later stages of World War I, the five infantry divisions of the First Australian Imperial Force (AIF)—comprised entirely of personnel who had volunteered for service overseas—were united as the Australian Corps, on the Western Front, under Lieutenant General Sir John Monash.

During World War II, the Australian I Corps was formed to co-ordinate three Second Australian Imperial Force (2nd AIF) units: the 6th, 7th and 9th Divisions, as well as other Allied units on some occasions, in the North African campaign and Greek campaign. Following the commencement of the Pacific War, there was a phased withdrawal of I Corps to Australia, and the transfer of its headquarters to the Brisbane area, to control Allied army units in Queensland and northern New South Wales (NSW). II Corps was also formed, with Militia units, to defend south-eastern Australia, and III Corps controlled land forces in Western Australia. Sub-corps formations controlled Allied land forces in the remainder of Australia. I Corps headquarters was later assigned control of the New Guinea campaign. In early 1945, when I Corps was assigned the task of re-taking Borneo, II Corps took over in New Guinea.

Canada

Canada first fielded a corps-sized formation in the First World War; the Canadian Corps was unique in that its composition did not change from inception to the war's end, in contrast to British corps in France and Flanders. The Canadian Corps consisted of four Canadian divisions. After the Armistice, the peacetime Canadian militia was nominally organized into corps and divisions but no full time formations larger than a battalion were ever trained or exercised. Early in the Second World War, Canada's contribution to the British-French forces fighting the Germans was limited to a single division. After the fall of France in June 1940, a second division moved to England, coming under command of a Canadian corps headquarters. This corps was renamed I Canadian Corps as a second corps headquarters was established in the UK, with the eventual formation of five Canadian divisions in England. I Canadian Corps eventually fought in Italy, II Canadian Corps in NW Europe, and the two were reunited in early 1945. After the formations were disbanded after VE Day, Canada has never subsequently organized a Corps headquarters.

France

The French Army under Napoleon used corps-sized formations () as the first formal combined-arms groupings of divisions with reasonably stable manning and equipment establishments. Napoleon first used the Corps d'Armée in 1805 . The use of the Corps d'Armée was a military innovation that provided Napoleon with a significant battlefield advantage in the early phases of the Napoleonic Wars. This innovation stimulated other European powers to adopt similar military structures. The Corps has remained an echelon of French Army organization to the modern day.

United Kingdom

The British Army still has a corps headquarters for operational control of forces. I Corps of the British Army of the Rhine was redesignated the Headquarters Allied Command Europe Rapid Reaction Corps in 1994 . It is no longer a purely British formation, although the UK is the 'framework nation' and provides most of the staff for the headquarters. A purely national Corps headquarters could be quickly reconstituted if necessary.

It took command of the International Security Assistance Force in Afghanistan on 4 May 2006. Previously, it was deployed as the headquarters commanding land forces during the Kosovo War in 1999 and also saw service in Bosnia and Herzegovina, commanding the initial stages of the IFOR deployment prior to that in 1996. Otherwise, the only time a British corps headquarters has been operationally deployed since 1945 was II Corps during the Suez Crisis.

United States

thumb|The XVIII Airborne Corps command group returns home from Operation Iraqi Freedom in 2009
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. In Civil War usages, by both sides, it was common to write out the number, thus "Twenty-first Army Corps", a practice that is usually ignored in modern histories of the war.

During World War I the American Expeditionary Forces (AEF) adopted the common European usage of designating corps by Roman numerals
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, 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.

Soviet Union

The pre-World War II Red Army of the former USSR had rifle corps much like in the Western sense with approximately three divisions to a corps. However, after the war started, the recently-purged Soviet senior command (Stavka) structure was apparently unable to handle the formations, and the armies and corps were integrated into new, smaller "Armies" and those into fronts. Rifle Corps were re-established during the war after Red Army commanders had gained experience handling larger formations. Before and during World War II, however, Soviet armored units were organized into corps. The pre-war Mechanized Corps were made up of divisions. In the reorganizations, these "Corps" were reorganized into tank brigades and support units, with no division structure. Due to this, they are sometimes, informally, referred to as "Brigade Buckets".

After the war, the Tank and Mechanized Corps were re-rated as divisions. During the reforms of 1956-58, most of the corps were again disbanded to create the new Combined Arms and Tank Armies. A few corps were nevertheless retained, of both patterns. The Vyborg and Archangel Corps of the Leningrad Military District were smaller armies with three low-readiness motorized rifle divisions each. The Category A Unified Corps of the Belarussian Military District (Western TVD/Strategic Direction) and Carpathian Military District (also Western TVD) were of the brigade pattern.

The Soviet Air Force used ground terminology for its formations down to squadron level. As intermediates between the Division and the Air Army were Corps—these also had three Air Divisions each.

Administrative Corps

In the British Army and the armies of many Commonwealth countries, a corps is also a grouping by common function, or an Arm or a Service (e.g. Intelligence Corps, Royal Logistic Corps, Royal Corps of Signals), performing much the same function as a ceremonial infantry or cavalry regiment, with its own cap badge, stable belt, and other insignia and traditions. The Royal Armoured Corps and the Corps of Infantry are looser groupings of independent regiments.

In Australia, soldiers belong foremost to a Corps which defines a common function or employment across the army. The Australian Army has a system of coloured lanyards, which each identify a soldier as part of a specific Corps (or sometimes individual battalion). This lanyard is a woven piece of cord which is worn on ceremonial uniforms and dates back to the issue of clasp knives in the early 20th century which were secured to the uniform by a length of cord. If a soldier is posted to a unit outside of their parent corps, except in some circumstances the soldier continues to wear the hat badge and lanyard of their Corps (e.g. a Clerk posted to an infantry battalion would wear the lanyard of the Royal Australian Ordnance Corps)

In Canada, with the integration of the Canadian army into the Canadian Forces, the British Corps model was replaced with personnel branches, defined in Canadian Forces Administrative Orders (CFAOs) as "...cohesive professional groups...based on similarity of military roles, customs and traditions." CFAO 2-10) However, the Armour Branch has continued to use the title Royal Canadian Armoured Corps, the Infantry Branch continued to use the Royal Canadian Infantry Corps designation, and the Artillery Branch uses the term Royal Regiment of Canadian Artillery.

The Corps system is also used in the U.S. Army to group personnel with a common function, but without a regimental system there is less variation in insignia and tradition. These are often referred to as "Branches" and include the Quartermaster Corps, Ordnance Corps, Transportation Corps, Medical Corps, Chaplain Corps, Judge Advocate General's Corps, & Finance Corps. Each of these Corps is also considered a "Regiment" for historic purposes but these Regiments have no tactical function.

In the US, there are non-military, administrative, training and certification Corps for commissioned officers of the government's uniformed services such as the , the and the .

The Salvation Army

The Salvation Army calls its local units corps.

See also

• Military unit

• Corps area

• United States Marine Corps

• Eurocorps

• List of military corps

• List of corps of the United States

• Corps insignia of the United States Army

• Drum and bugle corps (modern)

• Drum and bugle corps (classic)

• Peace Corps

• Signal Corps

• United States Army Corps of Engineers

References and Further Reading

• Phisterer, Frederick, Statistical Record of the Armies of the United States, Castle Books, 1883, ISBN 0-7858-1585-6.

• Tsouras, P.G. Changing Orders: The evolution of the World's Armies, 1945 to the Present Facts On File, Inc, 1994. ISBN 0-8160-3122-3

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