After reaching the Seine, the objective of the first phase of Operation Overlord, the field army moved along the coast towards Belgium, with the Canadian 2nd Division entering Dieppe at the beginning of September.

The First Army, under acting command of Lieutenant-General Guy Simonds (from 28 September 1944 to 7 November 1944), fought the critical Battle of the Scheldt along with the supporting Operation Pheasant in October and early November, opening Antwerp for Allied shipping.

By this point, the field army, besides the II Canadian Corps, contained nine British divisions.

The Siegfried Line was broken and the field army reached the banks of the Rhine in early March.

In the final weeks of the war in Europe, the First Army cleared the Netherlands of German forces.

By this time the First Division and Fifth (Armoured) Division as well as First Armoured Brigade and the 1st Cdn AGRA had returned to the field army during Operation Goldflake, and for the first time, both the I Canadian Corps and II Canadian Corps fought under the same army commander.

The size of Canada's military contribution on its own would likely not have justified the creation of a separate army-level command in North-West Europe, especially over the period when I Canadian Corps was away gaining valuable combat experience in Italy.