The First Canadian Army was a major Allied ground unit in the Second World War. Originally formed in 1942 under Lieutenant-General Andrew McNaughton, it first had two corps made up from 5 divisions and an tank brigade. While it had been intended to be the headquarters for all Canadian ground forces in Europe, a division under it participated in the Dieppe Raid, one corps was sent to the Italian theater of operations, and the actual Canadian troops at the Battle of Normandy consisted of a corps under the Canadian army headquarters.
Two brigades of the 2nd Canadian Division served in the Dieppe Raid, and took terrible casualties. The raid, however, taught vital lessons about amphibious warfare.
For it to be a full-sized field army going into the Battle of Normandy, other Allied troops were assigned to the headquarters, now commanded by LTG Henry Crerar, who had commanded I Canadian Corps in Italy. It made up the left flank of the 21st Army Group under GEN Bernard Montgomery, later Field Marshal Viscount of Alamein.
The operational unit in the Normandy landing was II Canadian Corps. The Army headquarters became operational on July 23, following the June 6 landing, and after the 4th Canadian (Armoured) Division had completed its conversion from an infantry division. As an army, it fought in the Falaise Gap.
The Army fought at the Battle of the Scheldt in Belgium and the Netherlands, under Crerar's tactical command. Canadian troops returned from Italy, and the Army was a principally Canadian force in the Rhineland campaign.