The mountain men era ended because the beaver was almost drove to extinction in that area and because of fashion. Yes, the change of fashion caused the mountain men era to end. Afterward though many of them became a guide for that area since they had lived there for while.
Answer:
so everyone in NASA could be safe and able to work together
Congress would find it difficult to go to war against another country, because there was no national army or navy to begin with. As well, it did not have the power to enforce laws or tax, so it wouldn't have been able to raise money for a war either.