I've seen indications that some of the people involved in the Armenian Genocide with killing Armenians at the local level took the jihad declaration seriously (so they could take their stuff).
That would make sense. If you are commiting heinous actions in pursuit of your perceived interest, some sort of religious legitimacy to such actions comes handy and welcome (Islamic religious war laws would not, in general, condone the actions in question in the pursuit of military Jihad: civilians in warfare are legally protected - but this is immaterial from that perspective).