These men volunteered to fight against the German Kaiser's armies - not against Russian workers and peasants.
In the US. Infantry Manual published during World War II, the soldier was told what to do if a live grenade fell into the trench where he and others were sitting: to wrap himself around the grenade so as to at least save the others. (If no one "volunteered," all would be killed, and there were only a few seconds to decide who would be the hero.)Anatol Rapoport