The First Canadian Army was the senior Canadian operational formation in Europe during the Second World War. The Army was formed in early 1942, replacing the existing unnumbered Canadian Corps, as the growing number of Canadian forces in the United Kingdom necessitated an expansion to two corps. By the end of 1943 Canadian formations in the UK consisted of three infantry divisions, two armoured divisions, and two independent armoured brigades. The first commander was Lieutenant-General A.G.L. "Andy" McNaughton, who was replaced in 1944 by General H. D. G. "Harry" Crerar. Both had been senior artillery officers in the Canadian Corps in the First World War. Allied formations of other nationalities were added to the First Canadian Army to keep it at full strength.