Ghosts of people only appear if their souls are not at rest, so the best thing you can do is pray for your uncle. If that is not enough, and you find you are still being bothered, then you should ask you mother to invite a priest to come and bless the house.
I know I would be scared to see a ghost while having a shower or brushing my teeth! Try to avoid the bathroom where he died in. Maybe you can have showers somewhere else, like at a reletives place.
If your brave enough, you could actually go in there with your mom and talk to him and say to not show himself because it kind of scares you, just have a friendly talk like you would if he was alive. Goodluck! :).
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.