'If we choose "reaction" vs. "progress" as our litmus test, we will find ourselves on the side of empire in Afghanistan and any number of other conflicts.'
Really? I think you have more faith in the US army's ability to improve people's lives than I have.
and further: "How long do you imagine it might have lasted without military conflict? Economic forces sufficed to destroy it in most of the hemisphere pretty much simultaneously"
But that is a false opposition. Nothing happens by economics alone. There would have had to have been some kind of conflict for the slaveowners to have been forced out of their social position.
'It seems pretty obvious to me that the Union chose war for all the predictable economic reasons (tariffs, etc.) and used abolitionism - which took on a life of its own - to rally the proles.'
Not obvious at all. Crazy, really, to differentiate the 'economic reasons' from abolition which was both an economic and a social reason. The proles, were often more sympathetic to the South, at least the more backward New York Irish elements, though Marx's ally Joseph Weydemeyer did a good job rallying the German-American working class.
'for the majority of the South's population, it wasn't one country'
- apart from those southern blacks who identified with the North, of course.
'Looking backward it is easy to see that the world would probably be much better off if the U.S. had been Balkanized'
Far from it, it would have been a carnival of reaction that would have spread outwards from America to Europe and beyond. Most likely neither Germany nor Italy would have been unified, and Imperial Russia would still be a power in Europe.