Excellent film, gripping and breathtaking. Nothing in the way of current USA politics in it and that is a good thing.
Centres on a Press 4WD with 4 journalists including a young woman barely out of adolescence who's arc from naif to crack war photographer provides much of the development of the movie.
I found myself riveted to the action and somewhat breathless as I watched a great nation tear itself into ribbons, and found myself grasping at why that was happening.
As far as the backstory is concerned, the film makers thought of it all first and were just as alert to the strangeness of a Californian - Texan alliance as anybody else. It all works magnificently.
I have not yet really begun to think about this movie and it's more complex meanings as it carries the civil war through pretty countryside into Washington DC and the White House.
I heartily recommend it.