The problem isn't so complicated as you might think. In general, you can only map an aesthetic once. So calling scale_colour twice makes no sense to ggplot2.
It will try to force one into the other.
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.