Good topic for a 30 page research paper that has to have something to do with WWI or WWII?

I am really interested in the causes and effects of WWI or WWII and want to write about it for my focus research cl but I have no idea how I can form a thesis around it. I was thinking about writing about how Pearl Harbor directly led to the emergence of the United States as a superpower but that seems too overused. Is there any way I can change it a little to make it more unique or out of the box? My teacher suggested that our theses and therefore our papers should be "discussion-sparking with the ability to be argued."