If you can get close enough to photograph your subjects with it at the magnification you want, the 100mm would be a very good choice. For some pictures of live insects or other animals you might need the increased working distance of the 180mm. Besides the increased cost of the 180mm, the depth of field, always shallow at macro distances, is even shallower with the 180mm than shorter distances.
So the 180mm would not be the best choice if the working distance of the 100mm would be enough for what you want to do.
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.