All the basic building materials are in place, now it's missing just a few "main beams".
It's all due to the war, every family needs to repair their houses after the war, so there's a rush to snatch "building materials", which is why Hudson can't get his hands on the "main beams".
If it weren't for the title of Commander in Chief attracting some talents to join him, perhaps even those "bricks and tiles" wouldn't be available to Hudson.
Just because they can't be drawn over doesn't mean they can't be used. At the very least, Hudson can still command these people while serving as the Commander of the Army.
For example, arranging a few assistants to go over and learn, they all still have to give him some face.
The more he can teach, the better. Even if a hundred people are arranged to go out, and only one can succeed, it would still be a bargain.
