Manufacturing consent for war isn't just about convincing EVERYONE they want to fight a war. Part of it is marginalizing the dissenting opinion so hard, that people who otherwise might have qualms about your warmongering, are too worried about the social consequences of speaking out in FAVOR of the demonized "enemy" and if you do it well enough this creates a void that acts to prevent the uninformed from ever even asking the question "should we be fighting this war?"
How it do with Canada?