Because Hitler never wanted to fight Great Britain, that is why he let them retreat across the English channel at Dunkirk instead of ending the war right then and there. Hitler desperately wanted an alliance with Britain against the Soviet Union, because he saw communism as a threat to the entire world, a threat he wanted to extinguish.
He was put off by the Battle of Britain. An invasion of Britain was going to be hard anyway and probably would not have succeeded. Also, he didn't think Britain was enough of a threat to the might of the Nazis who had pretty much conquered Europe by then, and wanted to focus on defeating Russia, which he had wanted to do from the beginning of the war.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.