 German historian Sven Felix Kellerhoff argued that, instead of fear of punishment the participants were more afraid of peer pressure and the possibility of exclusion from their group.Kellerhoff further argued that the situation of "Einsatzgruppen" members taking part in massacres did not even constitute the lesser "Putativnotstand", a state where the individual mistakenly believes their life is in danger if the order is disobeyed when, in reality, no such danger exists.Manfred Oldenburg, in his book "Ideology and Military Calculation", stated that there are no known cases where the refusal to participate in an execution of civilians has led to drastic consequences for soldiers of the Wehrmacht or SS.