A strong contender for “best hidden Dylan song”, “Cross the Green Mountain” was written and recorded for the film Gods and Generals. I had forgotten that this film even existed. This is a Civil War film that was entirely financed by Ted Turner as a personal pet project. It was then nearly universally loathed by critics and faded into oblivion. I don’t think that I have ever so much as heard someone mention it. I’ve never seen it, I don’t think I’ve ever really had the opportunity to see it, and I can’t imagine that I will ever see it.
However. It has an eight-minute Dylan epic on it. A Dylan epic with fiddle! This is a really simple song, musically repetitive with Dylan sing-talking a long story. It’s nearly a perfect use of his talents by this point in his career. I am sure it must be the best thing in the film (my guess is that it likely plays over the end credits). Seems like it may have been a bid for a second Oscar, but for that to happen some one in the Academy probably has to watch the film. So no luck on that.
Dylan included this song on Bootleg Series v8: Tell Tale Signs, which is where I first heard it. Had he done so, it might have been forgotten by all but the most hardcore (actually, it probably still is – my guess would be that that is the least purchased part of the entire Bootleg Series to date). It really is too bad, because this one ranks among his best epic songs. It should be far better known than it is.
Here is a sadly abbreviated version that was used as the official music video. It will give you a taste, but you want the whole thing.
LongAndWastedYear 
For all sorts of reasons, I grew up as a serious Civil War buff, and despite all sorts of other reasons I have remained one. Movies like GODS AND GENERALS, and the Civil-War-reenactor subculture that made it and its predecessor, GETTYSBURG, possible, are among those other reasons. GETTYSBURG was sorta half-decent in a Civil-War nerd trainspotting kind of way–Roger Ebert gave it a thumb’s-up while Gene Siskel gave it thumb’s-down for being (I may or may not be paraphrasing here) “bloated Southern propaganda.” All early indications for the second film were that Ted Turner decided the best thing to do was to go all-in on “bloated Southern propaganda,” so I’ve avoided this one like the plague. However, I do love this line from Wikipedia: “Darius N. Couch was played by actor Carsten Norgaard.” I’m the kind of person who knows who Darius Couch was; sadly, I’m not the kind of person who knows who Carsten Norgaard is.