Well, here’s the thing. Rumpel had the power to get rid of the ogres, as we know. That means Zoso has that power. The Duke could have ordered him to get rid of the ogres, but instead, he used him to keep his subjects in-check.
I was just thinking that the other day — if Rumple could just blow up the Ogres, then why didn’t the Duke when he had the dagger? I’m guessing the war was politically expedient.
I can’t remember now, but weren’t the Ogre wars about human encroachment / (or, essentially, colonialism) — I have the feeling we learn this in one of the Belle/Gaston episodes? Or is that the 2nd Ogre War, and the first one has other reasons?