Those who have fallen so far away from home, without every saying bye to the ones they love, that is too horrible to fully comprehend but should be remembered so less wars will start.
Politicians and desk potatoes in the upper military ranks are responsible for wars - but hardly ever been up front or in the army at all.
Best solution would be to drag those to the front, but show them more than just the "we are winning and everything is going great" stuff - like the sad eyes of POWs, destroyed cities or your wounded, screming and crying soldiers.
I'm sure that the view of burnt, halfway living corpses, torn away legs and scarred faces will make them reconsider their decision.