The problem is these ideas take time. It's not a single generation that does it, but multiple generations. Germans didn't go from outsiders to rulers overnight.

But, then we have to realize the mechanism for that slow down was the speed of travel at that time. Germans could travel faster than Romans. It's actually why so many middle eastern people have trade as a major part of their culture, they are the roads to other lands.

Today, I can drive from Aberdeen to London in 8ish hours depending on traffic. I can get to the other side of Europe in a day pretty easily. I can contact people and do trade with someone around the world with my phone.

Then we have to include propaganda. The English are the best at it. They convinced German Submarine leadership to not use the most effective method for submarines during world war I. They almost convinced the Irish that it was ok to be British. They convinced themselves that they were winning battles in Africa and Europe throughout world war II. All major propaganda is based on their methods and the Canadian system has used it directly.

So, I would guess 2 generations.