Did any of the implicated politicians adopt the revisionist narrative, or did they just pander to (or for that matter possibly believe) to those who might prefer it on the basis of some of its elements?

Not sure how it relates precisely, but you'll sometimes see the revisionist narrative under the following superficially plausible formulation: The Southern states "obviously" had the right to secede, so were in the right as far as the nominal causes of war go. Therefore, the Union cause was unjust on its own terms, and the Northerners themselves for the most part, incl. Lincoln, were actually in the wrong. Abolition was a good if unintended consequence of the whole thing, but, if you believe that slavery was on the way out anyway, then the 600,000 dead couldn't have been worth it. I think Ron Paul and many in his zone might have moseyed on up to this one, but I don't think I've ever seen any major mainstream politician embrace it openly.

(great header image on your blog, by the way, but you already know I think that - I'm glad it's "out there")

I think the Southern Cons and the LLs drive the revisionist discussion, cuz they're the only ones with enough of a stake in it, though there's a usual distribution of nuts and bolts - skeptics, cranks, and so on - across the landscape geographically and politically. You could divide the former group into "Southern Patriots" and "libertarians," with the latter not wholly restricted to the South, and with overlap - including among neo-Confederate "racialists." Very hard to say which comes first, of course, the attachment to the land or the attachment to locally adaptive ideologies.

Yes, the two questions are different, but if we separate them entirely, then we have on the one hand a war that "just happens," and in itself has no human meaning - like two types of bacteria competing for control of a Petri dish, or even less meaningful than that - and on the other hand people whose motivations were materially irrelevant, whatever we might imagine they say about the individuals personally. (It would still be in the final analysis meaningless, but we might prefer to sustain an illusion of meaningfulness.) To the extent the events under such a construction constitute history at all, it's history as the succession of meaningless events - not really "interesting" to us. It's a morally irrelevant version of "historical cause," the "x-type bacteria respond to a-type stimuli more energetically than y-type bacteria because of b-type condition" kind of cause. For the historical "cause" in the other sense (the same sense as "Lost Cause") to mean something for us today, to engage our "interest," it has to represent a to us identifiable and interpretable, fully human striving on whatever appropriate level - life of the nation, life of the community, life of the individual, etc. - separately and as each informs the others. "Fully human" must include a moral dimension, and a moral dimension requires an idea of moral choices by the individual, community, nation that were meaningful.

As for measuring the competing narratives, I think you're asking whether or not I accept that one narrative can be said to be more accurate as a description than another, and that it must matter. If the meanings were only externally imposed to serve whatever purposes, then the whole question would be absurd in the other way: Maybe someone finds it advantageous to believe that Lincoln precipitated the Civil War in order to kill vampires threatening to take over the world. So who's to say it's wrong?

Those of us with a stake in some other narrative or interpretation look to the historical evidence, and may find other explanations somewhat better supported than "it was vampires". My view is that the evidence matters very much, but that on the historical questions truly important to us, the ones crucial to our own sense of ourselves, the meaning of our lives if any, the questions that are proxies for our own possible relations to self and others and past and future, we cannot expect the bare facts to do the work for us, and expecting them to do so itself tends to reflect and reinforce a distortive and impoverished sense of self, meaning, possibility.