You do have some say in the process of deciding which posts you would like to serve in, even as an entry level officer. And if you have language skills, that will impact on which posts you are likely to get. A TEFL degree is not very significant within the Foreign Service.
However, the needs of the service are also a significant factor. They will try to honor your preferences, up to a point. However, there's no guarantee that you'll get what you ask for.
To some extent, it will depend on what you ask for. If every post is London, Paris or Rome, chances are pretty good you'll be disappointed sooner or later, and probably sooner. The Foreign Service currently requires Foreign Service officers to do at least one hardship post every so many years.
That doesn't necessarily mean Afghanistan or Iraq, but those would certainly count.
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.