The Black Death killed 38 million people, it was a terrible illness which spread rapidly.
The Great Schism was in 1054 and the Christian church broke up into two sections, which essentially divided the Church with two popes.
I would say that trade would be "believed to travel to Europe because of this", because it would not really fit anywhere else.
Now, I'm not two sure on the last one but the Hundred Years War was where King Edward the III of England thought that he should be the king of France, so there was a very long battle between the two. I would say the Hundred Years War would be started by division of the heir to the throne of England, and France and Italy did not agree who was to be pope. Since the Hundred Years War had really nothing to do with Italy.
I think its water and iron
My guess is New York City
