I'm curious how he defines "imperial war". I wouldn't have considered either of the world wars, from the perspective of allied countries, to be imperial ones, but I might be mistaken. Unless we consider mutual defense treaties to be imperial? Cause that'd be Putin talk if said today about NATO.
Also, while the command was under Byng, the plan of attack on the ridge was crafted because of extensive research and planning from Canadian officers. I feel like just saying "well Byng was in command" ignores their contributions and the significance of the British command officers willing to approve a plan created by "colonial" officers.
Also, the fact that the French failed in their objective in the follow up doesn't really diminish the success of the attack. The French lost 150k men trying to take Vimy, as one of (arguably) the strongest nations on the planet. We, a colonial power, took it when they could not. We were given an objective, one that had previously failed. And we succeeded. Another army failing their objective several days later doesn't mean we didn't succeed.
I get the want to reject fantastical notions of the battle and I would argue that it was WW1 as a whole and not vimy itself that earned us a spot at the table on a national stage, but I feel like his analysis of the battle is necessarily negative.
An imperial war is any war where we send troops but they send the officers.
The dominion of Canada was forged into being with a stroke of a pen what legitimized it was the actions that certified it. Like a marriage not consummated can be contested so to can a nation narrative be undermined if it is not buttress by the actions of its citizens.
The difference between the World Wars is that in World War I we didn't have any real say in whether we did so. Britain still had formal control of our foreign affairs, so when it declared war the Dominions were automatically part of it.
In 1931, the Statute of Westminster gave the Dominions an equal constitutional status with Britain itself. They all continued to have the King as a monarch, but they now technically each had a "separate" Crown that had its own full set of powers. The Canadian Crown is separate from the British one, and we could potentially set our own succession rules if we wanted to, so that a different person takes the throne instead of the Prince of Wales whenever King Charles passes.
We could've actually sat out World War II if we wanted to, but public opinion would never allow that. William Lyon Mackenzie King, our Prime Minister at the time, got Parliament to authorize Canada's own separate declaration of war on the Axis, but he deliberately waited ten days after Britain made its declaration to show that Canada would make its own independent decisions.