I know that it's not possible today, but the future is likely to have clone armies.
Think of all the benifits:
1. You don't have to remember anyone's name
2. If anyone dies just make more
3. They will all be cloned from someone with the best characteristics and the most appropriate soldier's mentality.
4. Everyone is the same blood group so less trouble for transfusions
Yet if clones are used, maybe this will distance people's views of war, and perhaps make it seem not so bad if there is little cost to human life.