The unnumbered Canadian Corps was the first corps-level military formation established by the Canadian Army during World War II. A four-division Canadian Corps had existed during the First World War. However, during World War II Canada's military contribution was to increase to the scale of a five-division, two-corps army. British staff officers in the new Canadian Corps were replaced gradually with Canadians as trained replacements became available. Similarly, British units in the Corps were gradually replaced with Canadian units.