Within military terminology a corps may be:
These usages often overlap. For example, during the Korean War, the United States' X Corps – a field corps – included infantry units from the US Marine Corps and smaller units from many different administrative corps of the US Army.
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 Western armies with numbered corps, the number is often indicated in Roman numerals (e.g., VII Corps).
In the later stages of World War I, the five infantry divisions of the First Australian Imperial Force (AIF)—consisting 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.