I think you will have to keep all those overlays that you are making in for loop (MapRouteOverlay) in some kind of list, then when you click on next overlay, you will have to remove all those from map............
As I see in your code you add your route to the map with.
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.