The first 2 years you have a green card, it is provisional...that means it expires in 2 years, and you must be sure you do not leave the country with an expired or soon to expire green card. Be sure you have your "permanent' card. Then, you cannot be outside the US more than one year without applying for a "re-entry permit" before you leave.
You cannot be outside the US for more than a total of 2 years. You cannot establish a home, take a job in another country without risking the loss of your green card. See site below.
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.