A Corps ( "core"; plural /ˈkɔərz/ 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

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.