I believe it's different based upon the situation. If a man enters into a situation knowing full-well of the risks he's about to undertake and being under no obligation accept, then yes, I believe responsibility lies on his shoulders.

When somebody is dependent upon you, or ignorant, or... your subordinate, it's different. I will always feel responsibility for the deaths of my men, but they were my soldiers. I wasn't yours. The actions of a knowing volunteer and an insane zealot are not on your hands.