An odd book who's heart seems to be in the South: The March

Some of the scenes in E.L. Doctorow's The March that depict life on the ground in Sherman's Army of occupation during the march through Georgia and north into the Carolinas are completely harrowing and quite credible - not sure how many sources Doctorow used or to what extent and how much of this - most I would think, it doesn't feel fusty and source-heavy - is based on his imagination and ability to place himself amid the lives of others - especially part 2, the occupation and destruction of Columbia. It's a very odd book - makes us feel like almost none other the lives of ordinary soldiers and others affected by the war - freed slaves, Confederate conscripts the various hangers-on such as a licensed war photographer - but it also feels as if there's something missing, maybe intentionally. That is, there's almost no sense at all as to what the war is about; the soldiers, even the generals (Sherman et al) don't seem to be fighting for a cause - they're fighting for a because: because they're professional soldiers, because they were conscripted, because they had no future so they took the place of a draftee for $300, because their home was destroyed and they have no place to turn, because they're uneducated and are just following a crowd. The March itself is a great, inhuman force - like a tide rather than a movement; it may seem surprising but ELD's sympathies seem to be more with the South - the destruction of the Southern cities is depicted as cruel and pointless, and to make matters worse the Union soldiers brutally rape the Southern women, the freed slaves especially - so, yes, no doubt this happened, but that happened to the slaves for the past 200 years, with impunity? I don't want the novel to be preachy or ideological, but at times is does feel like an apologia - not as much so as the loathsome Gone with the Wind and its ilk but you can't help passing through this book without thinking that the Union Army was pretty repugnant. One other note: ELD deserves a lot of credit for his handling of the many strands, most but not all intersecting, of the plot and in particular for his willingness to break convention and have key characters die in action and to write a story in which the obvious, too obvious, romantic connections turn out very often to be false leads: the Southern belle who joins a Union army medical team ends up walking away from the surgeon rather than falling for him, for ex.