They were, to an extent:
There weren’t enough Royal Marines available at the time of Operation Jubilee within the UK (there were only about 1 to 1 1/2 divisions’ worth of RM troops for all RM needs worldwide), and the Canadian government had been making a big hairy nuisance of itself trying to get some combat experience for at least some of the Canadian troops in England, so the British slotted in a Canadian division for the main ground combat role in the assault.
At this time it was not accepted that the main role of marines was for amphibious operations. That is actually a policy decision taken by the United States Marines in the 1930’s. Until the end of WWII, amphibious operations were actually equally an army task in the US and UK.
At thus time Royal Marines were mainly deployed aboard warships, their traditional role.
Canada, even to this day, has never had a Marine Corps. And we probably never will. And the the idea of getting Canadians experience is true, as besides Hong Kong and a brief stint in France, the Canadian army had spent the war “guarding” England while the rest of the Commonwealth was pulling their weight. This was to do with the threat of the Conscription Crisis and the “Zombies”.
This had been true up until the First World War, when the Royal Marines and “surplus” navy personnel were organized into the Royal Naval Division, which served on the western front and in the Gallipoli campaign. Most Royal Navy capital ships had a main gun turret manned by Royal Marines (usually the X or Y turret). After WW1, with the reduction in size of the Royal Marines official establishment, relatively few marines were trained in artillery, and most instead were trained as light infantry.
In WW2, the Royal Marine Brigade (later expanded into the Royal Marine Division) was formed in 1940, and units of the Brigade/Division served in several operations. The RMD was still primarily a light infantry organization of only two brigades and would not have had the combat “weight” of a full infantry division with all supporting arms.
I think the “zombie” issue arose later in the war, when voluntary recruiting was no longer sufficient to maintain the combat strength of Canadian units in the field (especially after 1st division landed in Sicily and began taking casualties).
The actual issue was the wish of the Canadian Governmemt for Canadian troops to remain under Canadian command, rather than be used as reinforcements for British units. The conscription crisis didn’t occur until 1944.
Canada was always the most independently-minded Commonwealth member at this time.
It’s true the Conscription Crisis didn’t happen fully until 1944, but it was brewing for some time. There was a reason the Canadian Army didn’t see much action until Italy, to keep casualties down. But you’re not wrong either.
Every nation ran up against a manpower wall at one point or another. Britain ran into manpower shortages in 1944 too.
Canada’s strategic role wasn’t to provide land forces, it was to produce supplies and act as a manufacturing base. To that end the role and expansion of the Royal Canadian Navy was clearly necessary.
The Army and Air Force were more optional; remember at this time Canada had a marked disinclination to fight Britain’s colonial wars, which was why our Pacific War involvement was so limited.
New Zealand and Australia were not and could not be the manufacturing base Canada was.
It’s hard to see what a Canadian involvement in North African land operations would achieve. In all honesty, it wouldn’t have made much of a difference. At this time, that WAS the Western Allied land war.