An American travelling on an ETA is unlikely to have a problem because of not having a return ticket but there's no guarantee that will be the case. Easiest way to avoid problems (and probably cheapest) is to buy a return ticket with an open return. If you really don't want a return ticket even with an open return, take some kind of evidence that you need to be back in the states within 3 months e.g. a letter from your employer.
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.