This varies by school. What I'd recommend is that you send an email to each professor, letting him know that you'll miss the first class. Don't tell him it's for a vaca - just say you'll miss, and apologize.
Ask them not to drop you from the class; that you WILL be there for the second class. This should be sufficient. Then contact your advisor to find out what the drop policy is at your school, or look that up online.
Make sure you know for sure that you cannot be dropped for missing the first class. At most schools, you won't be; but at some, you would be - so find out.
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.