I think it is difficult to improve very much on what you have. Python lists are relatively cheap to build and append; NumPy arrays are more expensive to create and don't offer a .append() method at all. So your best bet is to build the lists like you already are doing, and then coerce to np.array() when the time comes.
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.