<<The units for Overlord were contributed on a divisional basis. In general, 4 divisions make up one army. Canada contributed 5 divisions to Overlord, the US contributed 21 divisions.>>
From what I recall, there were six armies, six invasion beaches. The U.S. had Omaha and two others, the Canadians had Juno Beach, the British had Sword and one other. How many divisions went into an army on D-Day for the invasion, I have no idea, nor whether each division had roughly the same number of men, nor whether each army had the same number of divisions. The fact is, without in any way attempting to minimize the American contribution, Canada was NOT a bystander as the Professor implied, they were the only Ally to send an army to Normandy and to take one of the invasion beaches.
<<Also, the US had numerous divisions in other theaters of the war at the same time. Canada had few elsewhere.>>
Canada was always about one-tenth the population of the U.S.A. From what I can recall of the WWII casualty figures, Canada's casualties were much more than one-tenth of the U.S.A.'s. We did our share and IMHO much more than our share.