Some scholars date the beginning of the period in terms of sensibilities and political concerns to the passage of the Reform Act 1832.
Slavery for sure. I believe the second one is economic differences between the North and the South.
Yes i'd say so, at least that's what history has taught us. The largest empires were the ones who are known today as being "world powers" because since a lot of land belonged to them they held most of the power. A great example of this is the Roman Empire
