Did I ruin my chances of getting into a UC?

That is an extremely bad idea. Rigor of senior year course schedule is one of the top factors considered for UC application evaluation. You should aim to take 5-6 a-g courses with at least 4 of them being AP courses.

Senior grades are not calculated into your GPA; You can keep your UC acceptance as long as you keep a 3.0 GPA (weighted or unweighted depending on the UC campus) and not receive any D or F grades.

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.