Supreme Court is the highest court in USA
Isolationists didn't want to join European schemes or war efforts. The Lend-lease program was a program by the government to help send help to Europe but isolationists wanted to stay on their continent and not participate in any of the affairs there.
It permanently shifted the global balance of power.
Even after the unification, that gradually happened between 1815-1871, the conflict still continued mainly because of quite major regional and ethnic differences. Since Italy was separated for quite a long time, different traditions, views on politics, and much more appeared within these societies. If you take a closer look at the image below, you will see how many different societies lived separately. You could only imagine how diverse that area was.