Churchill saw the danger of getting expelled from Europe by the Nazi Army, as it happened years before after the Battle of Dunkirk.
The Allies were dominant in Northern Africa, and had military bases in Malta. Churchill thought that the Italian army was poorly equipped and trained, and thought that it was the most vulnerable point of the Axis. He referred to Italy as the "soft underbelly" of the Axis because of that.
Federalism because Amendments are proposed at a federal level and is ratified at a state level. Why have only 27 Amendments been added to the Constitution? Because of Informal Amendments and how easy it is to informally amend it rather than formally.