Can anyone recommend a good thread or timeline dealing with how a much later American Civil War between the North and South - in the 1880s or 1890s - would have been fought?
Depends a lot on what prevents the war from breaking out in 1861.
Is the US an armed camp, just waiting for a spark? Is there an era of good feeling, because Buchanan nipped it in the bud with a Jacksonian policy toward South Carolina?
You need a fairly compelling case as to why the secession winter of 1860-61 doesn't take place.