If you're going for the Killing Fields, why not just call it Apocalyse Now or Platoon?
Again, just think about what your story is about - revenge, regret, the horrors of war, triumph from disaster, etc. and derive the title from that. Obviously, the Oscar winning movie, the Killing Fields probably won't exist in the 41st Century, so it's applicable that your General would say that. Unfortunately, the readers do live in this century and they'll just say 'Hardly an original title'.
If you really want to stick on the Killing Fields idea, change it to something else like 'The Stomping Ground' or 'The Grinder' or ' The Devil's Playground'. None of my suggestions are original but they are a little more obscure then 'The Killing Fields'.
A quick and easy solution might be to do some research into military history and steal a name from past conflicts, it will have that ring of authenticity but will be obscure enough that everyone will think you made it up.
Please understand that I'm not having a pop, just trying to be helpful.